Network Working Group                               Frank Dawson, Lotus
Internet Draft                               Derik Stenerson, Microsoft
<ietf-calsch-ical-06.txt>                                March 13, 1998
<draft-ietf-calsch-ical-07.txt
Expires September six months after                                   May 11, 1998

     Internet Calendaring and Scheduling Core Object Specification
                              (iCalendar)

Status of this Memo

   This memo is an Internet-Draft. Internet-Drafts are working documents
   of the Internet Engineering Task Force (IETF), its areas, and its
   working groups. Note that other groups MAY can also distribute working
   documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months. Internet-Drafts MAY can be updated, replaced, or made obsolete by
   other documents at any time. It is not appropriate to use Internet-
   Drafts as reference material or to cite them other than as a "working
   draft" or "work in progress".

   To learn view the current status entire list of any Internet-Draft, current Internet-Drafts, please check
   the
   1id-abstracts.txt "1id-abstracts.txt" listing contained in the Internet-Drafts
   Shadow Directories on ds.internic.net ftp.is.co.za (Africa), ftp.nordu.net
   (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au
   (Pacific Rim), ftp.ietf.org (US East Coast), nic.nordu.net
   (Europe), or ftp.isi.edu
   (US West Coast), or munnari.oz.au (Pacific
   Rim). Coast).

   Distribution of this memo is unlimited.

   Copyright (C) The Internet Society 1997. All Rights Reserved.

Abstract

   There is a clear need to provide and deploy interoperable calendaring
   and scheduling services for the Internet. Current group scheduling
   and Personal Information Management (PIM) products are being extended
   for use across the Internet, today, in proprietary ways. This memo
   has been defined to provide the definition of a common format for
   openly exchanging calendaring and scheduling information across the
   Internet.

   This memo is formatted as a registration for a MIME media type per
   [RFC 2048]. However, the format in this memo is equally applicable
   for use outside of a MIME message content type.

   The proposed media type value is ''text/calendar''. 'text/calendar'. This string would
   label a media type containing calendaring and scheduling information
   encoded as text characters formatted in a manner outlined below.

   This MIME media type provides a standard content type for capturing
   calendar event, to-do and journal entry information. It also can be
   used to convey free/busy time information. The content type is
   suitable as a MIME message entity that can be transferred over MIME
   based email systems, using HTTP or some other Internet transport. In

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   addition, the content type is useful as an object for interactions
   between desktop applications using the operating system clipboard,
   drag/drop or file systems capabilities.

   This memo is based on the earlier work of the vCalendar specification
   for the exchange of personal calendaring and scheduling information.
   In order to avoid confusion with this referenced work, this memo is
   to be known as the iCalendar specification.

   Readers may also wish to refer to the calendaring and scheduling model
   defined in [] [ICMS] for a description of this Internet application.

   This memo defines the format for specifying iCalendar object methods.
   An iCalendar object method is a set of usage constraints for the
   iCalendar object. For example, these methods might define scheduling
   messages that request an event be scheduled, reply to an event
   request, send a cancellation notice for an event, modify or replace
   the definition of an event, provide a counter proposal for an
   original event request, delegate an event request to another
   individual, request free or busy time, reply to a free or busy time
   request, or provide similar scheduling messages for a to-do or
   journal entry calendar component. The iCalendar Transport-indendent
   Interoperability Protocol (iTIP) defined in [ITIP] is one such
   scheduling protocol.

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   Table of Contents

1 Introduction.........................................................8 Introduction.........................................................6
2 Basic Grammar and Conventions........................................8 Conventions........................................6
 2.1 Formatting Conventions ...........................................9 ...........................................7
 2.2 Related Memos ...................................................10 ....................................................8
 2.3 International Considerations .....................................8
3 TEXT/CALENDAR Registration Information..............................10 Information.............................................8
 3.1 Content Type .....................................................9
 3.2 Parameters .......................................................9
 3.3 Content Header Fields ...........................................10
 3.4 Encoding Considerations .........................................10
 3.5 Security Considerations .........................................10
 3.6 Interoperability Considerations .................................11
 3.7 Applications Which Use This Media Type ..........................11
 3.8 Additional Information ..........................................11
 3.9 Magic Numbers ...................................................11
 3.10 File Extensions ................................................11
 3.11 Contact for Further Information: ...............................12
 3.12 Intended Usage .................................................12
 3.13 Authors/Change Controllers .....................................12
4 iCalendar Object Specification......................................13 Specification......................................12
 4.1 Content Lines ...................................................13 ...................................................12
  4.1.1 List and Field Separators ....................................16 ....................................15
  4.1.2 Multiple Values ..............................................16 ..............................................15
  4.1.3 Binary Content ...............................................17 ...............................................16
  4.1.4 Character Set ................................................17 ................................................16
 4.2 Property Parameters .............................................17 .............................................16
  4.2.1 Alternate Text Representation ................................18 ................................17
  4.2.2 Common Name ..................................................18
  4.2.3 Calendar User Type ...........................................19
  4.2.4 Delegators ...................................................19
  4.2.5 Delegatees ...................................................20
  4.2.6 Directory Entry Reference ....................................20
  4.2.7 Inline Encoding ..............................................19
  4.2.3 ..............................................20
  4.2.8 Free/Busy Time Type ..........................................21
  4.2.9 Language .....................................................19
  4.2.4 .....................................................22
  4.2.10 Group or List Membership ....................................22
  4.2.11 Participation Status ........................................23
  4.2.12 Recurrence Identifier Range .................................24
  4.2.13 Alarm Trigger Relationship ..................................25
  4.2.14 Relationship Type ...........................................25
  4.2.15 Participation Role ..........................................26
  4.2.16 RSVP Expectation ............................................27
  4.2.17 Sent By .....................................................27
  4.2.18 Time Zone Identifier .........................................20
  4.2.5 ........................................27
  4.2.19 Value Data Types .............................................21 ............................................28
 4.3 Property Value Data Types .......................................21 .......................................29
  4.3.1 Binary .......................................................22 .......................................................29
  4.3.2 Boolean ......................................................22 ......................................................30
  4.3.3 Calendar User Address ........................................23 ........................................30
  4.3.4 Date .........................................................23 .........................................................31

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  4.3.5 Date-Time ....................................................24 ....................................................31
  4.3.6 Duration .....................................................25 .....................................................33
  4.3.7 Float ........................................................26 ........................................................34
  4.3.8 Integer ......................................................27 ......................................................34
  4.3.9 Period of Time ...............................................27 ...............................................35
  4.3.10 Recurrence Rule .............................................28 .............................................36
  4.3.11 Text ........................................................33 ........................................................40
  4.3.12 Time ........................................................34 ........................................................41
  4.3.13 URI .........................................................36 .........................................................43
  4.3.14 UTC Offset ..................................................36 ..................................................44
 4.4 iCalendar Object ................................................37 ................................................45
 4.5 Property ........................................................38 ........................................................45
 4.6 Calendar Components .............................................38 .............................................45
  4.6.1 Event Component ..............................................38 ..............................................46
  4.6.2 To-do Component ..............................................40 ..............................................48
  4.6.3 Journal Component ............................................41 ............................................49
  4.6.4 Free/Busy Component ..........................................43 ..........................................50
  4.6.5 Timezone Time Zone Component ...........................................45 ..........................................52
  4.6.6 Alarm Component ..............................................50 ..............................................58
 4.7 Calendar Properties .............................................53 .............................................61
  4.7.1 Calendar Scale ...............................................54 ...............................................61
  4.7.2 Method .......................................................54 .......................................................62
  4.7.3 Product Identifier ...........................................55 ...........................................63
  4.7.4 Version ......................................................56 ......................................................63
 4.8 Component Properties ............................................56 ............................................64
  4.8.1 Descriptive Component Properties .............................56 .............................64
    4.8.1.1 Attachment ...............................................56 ...............................................64
    4.8.1.2 Categories ...............................................57

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    4.8.1.3 Classification ...........................................58 ...........................................66
    4.8.1.4 Comment ..................................................59 ..................................................67
    4.8.1.5 Description ..............................................59 ..............................................67
    4.8.1.6 Geographic Position ......................................60 ......................................68
    4.8.1.7 Location .................................................61 .................................................69
    4.8.1.8 Percent Complete .........................................61 .........................................69
    4.8.1.9 Priority .................................................62 .................................................70
    4.8.1.10 Resources ...............................................63 ...............................................72
    4.8.1.11 Status ..................................................64 ..................................................72
    4.8.1.12 Summary .................................................65 .................................................73
  4.8.2 Date and Time Component Properties ...........................66 ...........................74
    4.8.2.1 Date/Time Completed ......................................66 ......................................74
    4.8.2.2 Date/Time End ............................................66 ............................................75
    4.8.2.3 Date/Time Due ............................................67 ............................................75
    4.8.2.4 Date/Time Start ..........................................68 ..........................................76
    4.8.2.5 Duration .................................................69 .................................................77
    4.8.2.6 Free/Busy Time ...........................................69 ...........................................78
    4.8.2.7 Time Transparency ........................................71 ........................................79
  4.8.3 Time Zone Component Properties ...............................72 ...............................79
    4.8.3.1 Time Zone Identifier .....................................72 .....................................79
    4.8.3.2 Time Zone Name ...........................................72 ...........................................80
    4.8.3.3 Time Zone Offset From ....................................73 ....................................81
    4.8.3.4 Time Zone Offset To ......................................74 ......................................82
    4.8.3.5 Time Zone URL ............................................74 ............................................82
  4.8.4 Relationship Component Properties ............................75 ............................83
    4.8.4.1 Attendee .................................................75 .................................................83

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    4.8.4.2 Contact ..................................................78 ..................................................85
    4.8.4.3 Organizer ................................................79 ................................................86
    4.8.4.4 Recurrence ID ............................................80 ............................................87
    4.8.4.5 Related To ...............................................81 ...............................................88
    4.8.4.6 Uniform Resource Locator .................................82 .................................89
    4.8.4.7 Unique Identifier ........................................83 ........................................90
  4.8.5 Recurrence Component Properties ..............................84 ..............................91
    4.8.5.1 Exception Date/Times .....................................84 .....................................91
    4.8.5.2 Exception Rule ...........................................85 ...........................................92
    4.8.5.3 Recurrence Date/Times ....................................86 ....................................93
    4.8.5.4 Recurrence Rule ..........................................88 ..........................................95
  4.8.6 Alarm Component Properties ...................................95 ..................................102
    4.8.6.1 Alarm Type ...............................................96 Action ..................................................103
    4.8.6.2 Repeat Count .............................................96 ............................................103
    4.8.6.3 Trigger ..................................................97 .................................................104
  4.8.7 Change Management Component Properties .......................98 ......................105
    4.8.7.1 Date/Time Created ........................................98 .......................................105
    4.8.7.2 Date/Time Stamp ..........................................99 .........................................106
    4.8.7.3 Last Modified ............................................99 ...........................................107
    4.8.7.4 Sequence Number .........................................100 .........................................107
  4.8.8 Miscellaneous Component Properties ..........................101 ..........................109
    4.8.8.1 Non-standard Properties .................................101 .................................109
    4.8.8.2 Request Status ..........................................102 ..........................................110
5 iCalendar Object Examples..........................................103 Examples..........................................111
6 Recommended Practices..............................................107 Practices..............................................115
7 Registration of Content Type Elements..............................107 Elements..............................116
 7.1 Registration of New and Modified iCalendar Object Methods ......107 ......116
 7.2 Registration of New Properties .................................108

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  7.2.1 Define the property .........................................108 .........................................116
  7.2.2 Post the Property definition ................................109 ................................117
  7.2.3 Allow a comment period ......................................109 ......................................117
  7.2.4 Submit the property for approval ............................109 ............................117
 7.3 Property Change Control ........................................109 ........................................118
8 References.........................................................109 References.........................................................118
9 Acknowledgments....................................................111 Acknowledgments....................................................120
10 Author's Address..................................................111 Address..................................................120
11 Full Copyright Statement..........................................112 Statement..........................................121

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1  Introduction

   The use of calendaring and scheduling has grown considerably in the
   last decade. Enterprise and inter-enterprise business has become
   dependent on rapid scheduling of events and actions using this
   information technology. However, the longer term growth of
   calendaring and scheduling, is currently limited by the lack of
   Internet standards for the message content types that are central to
   these knowledgeware applications. This memo is intended to progress
   the level of interoperability possible between dissimilar calendaring
   and scheduling applications. This memo defines a MIME content type
   for exchanging electronic calendaring and scheduling information. The
   Internet Calendaring and Scheduling Core Object Specification, or
   iCalendar, allows for the capture and exchange of information
   normally stored within a calendaring and scheduling application; such
   as a Personal Information Manager (PIM) or a Group Scheduling
   product.

   The calendaring and scheduling model, defined in the [ICMS], is a
   useful reference to terms and the general framework of this Internet
   application.

   The iCalendar format is suitable as an exchange format between
   applications or systems. The format is defined in terms of a MIME
   content type. This will enable the object to be exchanged using
   several transports, including but not limited to SMTP, HTTP, a file
   system, desktop interactive protocols such as the use of a memory-
   based clipboard or drag/drop interactions, point-to-point
   asynchronous communication, wired-network transport, or some form of
   unwired transport such as infrared might also be used.

   The memo also provides for the definition of iCalendar object methods
   that will map this content type to a set of messages for supporting
   calendaring and scheduling operations such as requesting, replying
   to, modifying, and canceling meetings or appointments, to-dos and
   journal entries. The iCalendar object methods can be used to define
   other calendaring and scheduling operations such a requesting for and
   replying with free/busy time data. Such a scheduling protocol is
   defined in the iCalendar Transport-independent Interoperability
   Protocol (iTIP) defined in [ITIP].

   The memo also includes a formal grammar for the content type based on
   the Internet ABNF defined in [RFC 2234]. This ABNF is required for
   the implementation of parsers and to serve as the definitive
   reference when ambiguities or questions arise in interpreting the
   descriptive prose definition of the memo.

2  Basic Grammar and Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" and

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   "OPTIONAL" in this document are to be interoperated as described in
   [RFC 2119].

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   This memo makes use of both a descriptive prose and a more formal
   notation for defining the calendaring and scheduling format.

   The notation used in this memo is the ABNF notation of [RFC 2234].
   Readers intending on implementing this format defined in this memo
   should be familiar with this notation in order to properly interpret
   the specifications of this memo.

   All numeric and hexadecimal values used in this memo are given in
   decimal notation.

   All names of properties, property parameters, enumerated property
   values and property parameter values are case-
   insensitive. case-insensitive. However,
   all other property values are case-sensitive, unless otherwise
   stated.

        Note: All indented editorial notes, such as this one, are
        intended to provide the reader with additional information. The
        information that is not essential to the building of a conformant an
        implementation
        of the specifications of conformant with this memo. The information is
        provided to highlight a particular feature or characteristic of
        the
        specifications. memo.

   The format for the iCalendar object is based on the syntax of the
   [MIME DIR] content type. While the iCalendar object is not a profile
   of the [MIME DIR] content type, it does reuse a number of the
   elements from the [MIME DIR] specification.

2.1 Formatting Conventions

   The mechanisms defined in this memo are defined in propose. prose. Many of the
   terms used to describe these have common usage that is different than
   the standards usage of this memo. In order to reference within this
   memo elements of the calendaring and scheduling model [ICMS], core
   object (this memo) or interoperability protocol [ITIP] some
   formatting conventions have been used. Calendaring and scheduling
   roles defined by [ICMS] are referred to in quoted-strings of text
   with the first character of each word in upper case. For example,
   "Organizer" refers to a role of a "Calendar User" within the
   scheduling protocol defined by [ITIP] [ITIP]. Calendar components defined by
   this memo are referred to with capitalized, quoted-strings of text.
   All calendar components start with the letter "V". For example,
   "VEVENT" refers to the event calendar component, "VTODO" refers to
   the to-do calendar component and "VJOURNAL" refers to the daily
   journal calendar component. Scheduling methods defined by [ITIP] are
   referred to with capitalized, quoted-strings of text. For example,
   "REQUEST" refers to the method for requesting a scheduling calendar
   component be created or modified, "REPLY" refers to the method a
   recipient of a request uses to update their status with the
   "Organizer" of the calendar component.

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   The properties defined by this memo are referred to with capitalized,
   quoted-strings of text, followed by the word "property". For example,
   "ATTENDEE" property refers to the iCalendar property used to convey
   the calendar address of a calendar user. Property parameters defined
   by this memo are referred to with lower case, lowercase, quoted-strings of text,

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   followed by the word "parameter". For example, "value" parameter
   refers to the iCalendar property parameter used to override the
   default data type for a property value. Enumerated values defined by
   this memo are referred to with capitalized text, either alone or
   followed by the word "value". For example, the "MINUTELY" value can
   be used with the "FREQ" component of the "RECUR" data type to specify
   repeating components based on an interval of one minute or more.

2.2 Related Memos

   Implementers will need to be familiar with several other memos that,
   along with this memo, form a framework for Internet calendaring and
   scheduling standards. This memo, [ICAL], specifies a core
   specification of objects, data types, properties and property
   parameters.

   [ICMS] - specifies a common terminology and abstract model;

   [ITIP] - specifies an interoperability protocol for scheduling
   between different implementations;

   [IMIP] specifies an Internet email binding for [ITIP];

   [IRIP] - specifies an Internet real time protocol binding for [ITIP].

   This memo does not attempt to repeat the specification of concepts or
   definitions from these other memos. Where possible, references are
   made to the memo that provides for the specification of these
   concepts or definitions.

2.3 International Considerations

   In the rest of this document, descriptions of characters are of the
   form "character name (codepoint)", where "codepoint" is from the US-
   ASCII character set. The "character name" is the authoritative
   description; (codepoint) is a reference to that character in US-
   ASCII or US-ASCII compatible sets (for example the ISO-8859-x family,
   UTF-8, ISO-2022-xx, KOI8-R). If a non-US-ASCII compatible character
   set is used, appropriate code-point from that character set must be
   chosen instead. Use of non-US-ASCII-compatible character sets is NOT
   recommended.

3  TEXT/CALENDAR  Registration Information

   The Calendaring and Scheduling Core Object Specification is intended
   for use as a MIME content type. However, the implementation of the
   memo is in no way limited solely as a MIME content type.

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3.1 Content Type

   The following text is intended to register this memo as the MIME
   content type "text/calendar".

     To: ietf-types@uninett.no

     Subject: Registration of MIME content type text/calendar.

     MIME media type name: text

     MIME subtype name: calendar

3.2 Parameters

   Required parameters: none

   Optional parameters: charset, method and method, component and optinfo

   The "charset" parameter is defined in [RFC 2046] for other body
   parts. It is used to identify the default character set used within
   the body part.

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   The "method" parameter is used to convey the iCalendar object method
   or transaction semantics for the calendaring and scheduling
   information. It also is an identifier for the restricted set of
   properties and values that the iCalendar object consists of. The
   parameter is to be used as a guide for applications interpreting the
   information contained within the body part. It SHOULD NOT be used to
   exclude or require particular pieces of information unless the
   identified method definition specifically calls for this behavior.
   Unless specifically forbidden by a particular method definition, a
   text/calendar content type MAY can contain any set of properties
   permitted by the Calendaring and Scheduling Core Object
   Specification. The "method" parameter MUST be the same value as that
   specified in the "METHOD" component property in the iCalendar object.
   If one is present, the other must also be present.

   The value for the "method" parameter is defined as follows:

        method  = 1*(ALPHA / DIGIT / "-")
        ; IANA registered iCalendar object method

   The "component" parameter conveys the type of iCalendar calendar
   component within the body part. If the iCalendar object contains more
   than one calendar component, component type, then different components are
     each specified once in a comma-separated list of values. multiple component parameters
   MUST be specified.

   The value for the "component" parameter is defined as follows:

        component       = ("VEVENT" / "VTODO" / "VJOURNAL" / "VFREEBUSY"
                        / "VTIMEZONE" / x-name / iana-token) ["," [WSP]
                          component]

     Optional content header fields:

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   The "optinfo" parameter conveys optional information about the
   iCalendar object within the body part. This parameter can only
   specify semantics already specified by the iCalendar object and that
   can be otherwise determined by parsing the body part. In addition,
   the optional information specified by this parameter MUST be
   consistent with that information specified by the iCalendar object.
   For example, it can be used to convey the "Attendee" response status
   to a meeting request. The parameter value consists of a string value.
   The parameter can be specified multiple times.

   This parameter MAY only specify semantics already specified by the
   iCalendar object and that can be otherwise determined by parsing the
   body part.

   The value for the "optinfo" parameter is defined as follows:

        optinfo = infovalue / qinfovalue

        infovalue       = iana-token / x-name

        qinfovalue      = DQUOTE (infovalue) DQUOTE

3.3 Content Header Fields

   Optional content header fields: Any header fields defined by [RFC
   2045].

3.4 Encoding considerations: Considerations

     This MIME content type can contain 8bit characters, so the use of
     quoted-printable or base64 BASE64 MIME content-
     transfer-encodings MAY content-transfer-encodings might be
     necessary when iCalendar objects are transferred across protocols
     restricted to the 7bit repertoire. Note that a text valued property
     in the content entity MAY can also have content encoding of special
     characters using a BACKSLASH character (ASCII (US-ASCII decimal 92)
     escapement technique. This means that content values MAY can end up
     encoded twice.

3.5 Security considerations: Considerations

   SPOOFING - - In this memo, the "Organizer" is the only person
   authorized to make changes to an existing "VEVENT", "VTODO",
   "VJOURNAL" calendar component and redistribute the updates to the
   "Attendees". An iCalendar object that maliciously changes or cancels
   an existing "VEVENT", "VTODO" or "VJOURNAL" or "VFREEBUSY" calendar
   component MAY might be constructed by someone other than the "Organizer"
   and sent to the "Attendees". In addition in this memo, other than the
   "Organizer", an "Attendee" of a "VEVENT", "VTODO", "VJOURNAL"
   calendar component is the only other person authorized to update any
   parameter associated with their "ATTENDEE" property and send it to
   the "Organizer". An

Dawson/Stenerson                   9             Expires September 1998 iCalendar object that maliciously changes the
   "ATTENDEE" parameters
     MAY can be constructed by someone other than the
   real "Attendee" and sent to the "Organizer".

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   PROCEDURAL ALARMS - - An iCalendar object can be created that
   contains a "VEVENT" and "VTODO" calendar component with an "VALARM"
   calendar components. The "VALARM" calendar component MAY can be of type
   PROCEDURE and MAY can have an attachment containing some sort of
   executable program. Implementations that incorporate these types of
   alarms are subject to any virus or malicious attack that MAY might occur
   as a result of executing the attachment.

   ATTACHMENTS - - An iCalendar object MAY can include references to Uniform
   Resource Locators that MAY can be programmed resources.

   Implementers and users of this memo should be aware of the network
   security implications of accepting and parsing such information. In
   addition, the security considerations observed by implementations of
   electronic mail systems should be followed for this memo.

3.6 Interoperability considerations: Considerations

   This MIME content type is intended to define a common format for
   conveying calendaring and scheduling information between different
   systems. It is heavily based on the earlier [VCAL] industry
   specification.

3.7 Applications which use this media type: Which Use This Media Type

   This content-type is designed for widespread use by Internet
   calendaring and scheduling applications. In addition, applications in
   the workflow and document management area may might find this content-type content-
   type applicable. The
     [ITIP], [IMIP] [ITIP] and [IRIP] [IMIP] Internet protocols directly
   use this content-type also. Future work on an Internet calendar
   access protocol will utilize this content-type too.

3.8 Additional information: Information

   This memo defines this content-type.

3.9 Magic numbers: Numbers

   None.

3.10    File extensions: Extensions

   The file extension of "ics" is to be used to designate a file
   containing an (an arbitrary set of of) calendaring and scheduling
   information consistent with this MIME content type.

   The file extension of "ifb" is to be used to designate a file
   containing free or busy time information consistent with this MIME
   content type.

   Macintosh file type codes: The file type code of "ical" "iCal" is to be used
   in Apple MacIntosh operating system environments to designate a file
   containing calendaring and scheduling information consistent with
   this MIME media type.

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   The file type code of "ifb" "iFBf" is to be used in Apple MacIntosh
   operating system environments to designate a file containing free or
   busy time information consistent with this MIME media type.

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     Person & email address to contact

3.11    Contact for further information: Further Information:

   Frank Dawson
   6544 Battleford Drive
   Raleigh, NC 27613-3502
   919-676-9515 (Telephone)
   919-676-9564 (Data/Facsimile)
   Frank_Dawson@Lotus.com (Internet Mail)

   Derik Stenerson
   One Microsoft Way
   Redmond, WA  98052-6399
   425-936-5522 (Telephone)
   425-936-7329 (Facsimile)
   deriks@microsoft.com (Internet Mail)

3.12    Intended usage: Usage

   COMMON

     Author/change controller:

3.13    Authors/Change Controllers

   Frank Dawson
   6544 Battleford Drive
   Raleigh, NC 27613-3502
   919-676-9515 (Telephone)
   919-676-9564 (Data/Facsimile)
   Frank_Dawson@Lotus.com (Internet Mail)

   Derik Stenerson
   One Microsoft Way
   Redmond, WA  98052-6399
   425-936-5522 (Telephone)
   425-936-7329 (Facsimile)
   deriks@microsoft.com (Internet Mail)

4  iCalendar Object Specification

   The following sections define the details of a Calendaring and
   Scheduling Core Object Specification. This information is intended to
   be an integral part of the MIME content type registration. In
   addition, this information MAY can be used independent of such content
   registration. In particular, this memo has direct applicability for
   use as a calendaring and scheduling exchange format in file-, memory-
   or network-based transport mechanisms.

4.1 Content Lines

   The iCalendar object is organized into individual lines of text,
   called content lines. Content lines are delimited by a line break,

Dawson/Stenerson                   12             Expires November 1998
   which is a CRLF sequence (ASCII (US-ASCII decimal 13, followed by ASCII US-ASCII
   decimal 10).

Dawson/Stenerson                   11            Expires September 1998

   Lines of text SHOULD NOT be longer than 75 characters, octets, excluding the line
   break. Long content lines SHOULD be split into a multiple line
   representations using a line "folding" technique. That is, a long
   line MAY can be split at between any point two characters by inserting a CRLF
   immediately followed by a single linear white space character (i.e.,
   SPACE, ASCII US-ASCII decimal 32 or HTAB, ASCII US-ASCII decimal 9). Any sequence
   of CRLF followed immediately by a single linear white space character
   is ignored (i.e., removed) when processing the content type.

   For example the line:

     DESCRIPTION:This is a long description that exists on a long line.

   Can be represented as:

     DESCRIPTION:This is a lo
      ng description
       that exists on a long line.

   The process of moving from this folded multiple line representation
   to its single line representation is called "unfolding". Unfolding is
   accomplished by removing the CRLF character and the linear white
   space character that immediately follows.

   When parsing a content line, folded lines must first be unfolded
   according to the unfolding procedure described above. When generating
   a content line, lines longer than 75 characters octets SHOULD be folded
   according to the folding procedure described above.

   The content information associated with an iCalendar object is
   formatted using a syntax similar to that defined by [MIME DIR]. That
   is, the content information consists of one or more CRLF-separated
   content lines.

   The following notation defines the defines the lines of content in an
   iCalendar object:

     contentline        = name *(";" [WSP] param ) ":" value CRLF
        ; This ABNF is just a general definition for an initial parsing
        ; of the content line into its property name, parameter list,
        ; and value string

     ; When parsing a content line, folded lines must first
        ; be unfolded according to the unfolding procedure
        ; described above. When generating a content line, lines
        ; longer than 75 characters octets SHOULD be folded according to
        ; the folding procedure described above.

     name               = x-name / iana-token

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     iana-token = 1*(ALPHA / DIGIT / "-")
     ; iCalendar identifier registered with IANA

Dawson/Stenerson                   12            Expires September 1998

     x-name             = "X-" [vendorid "-"] 1*(ALPHA / DIGIT / "-")
     ; Reservered for experimental use.  Not intended for use in
     ; released products.

     vendorid   = 3*(ALPHA / DIGIT)     ;Vendor identification

     param              = param-name "=" param-value
                          *("," param-value)
        ; Each property defines the specific ABNF for the parameters
        ; allowed on the property. Refer to specific properties for
        ; precise parameter ABNF.

     param-name = iana-token / x-token

     param-value        = paramtext / quoted-string

     paramtext  = *SAFE-CHAR

     value      = *VALUE-CHAR

     quoted-string      = DQUOTE *qtext *QSAFE-CHAR DQUOTE

        qtext

     NON-US-ASCII       = QSAFE-CHAR / QUOTED-CHAR

        NON-ASCII       = %x80-FF %x80-F8
     ; Use restricted by charset parameter
     ; on outer MIME object (UTF-8 preferred)

     QSAFE-CHAR = WSP / %x21 / %x23-5B %x23-7E / %x5D-7E / NON-ASCII NON-US-ASCII
     ; Any character except CTLs, DQUOTE, or "\"

        QUOTED-CHAR     = "\" ("\" / "," / DQUOTE)
        ; \\ encodes \, \" encodes " CTLs and DQUOTE

     SAFE-CHAR  = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E
                / NON-ASCII NON-US-ASCII
     ; Any character except CTLs, DQUOTE, ";", ":", ","

     VALUE-CHAR = WSP / VCHAR %x21-7E / NON-ASCII NON-US-ASCII
     ; Any textual character

        VCHAR          =  %x21-7E
        ; visible (printing) characters

     CR = %x0D
     ; carriage return

     LF = %x0A
     ; line feed

     CRLF       = CR LF
     ; Internet standard newline

     CTL        =  %x00-1F %x00-08 / %x0A-1F / %x7F
        ; Controls

     ALPHA      = %x41-5A / %x61-7A   ; A-Z / a-z

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     DIGIT      = %x30-39
        ; 0-9

     DQUOTE     = %x22
        ; Quotation Mark

     WSP        = SPACE / HTAB

     SPACE      = %x20

     HTAB       = %x09

   The property value component of a content line has a format that is
   property specific. Refer to the section describing each property for
   a definition of this format.

   All names of properties, property parameters, enumerated property
   values and property parameter values are case-insensitive. However,
   all other property values are case-sensitive, unless otherwise
   stated.

4.1.1   List and Field Separators

   List

   Some properties and parameters allow a list of values MAY be specified for property values or property
   parameter values. Each value in
   a list of values MUST be separated by a COMMA character (ASCII (US-ASCII
   decimal 44). There is no significance to the ordering of values in a
   list. For those parameter values (such as those that specify URI
   values) that are specified in quoted-strings, the individual quoted-
   strings are separated by a COMMA character (US-ASCII decimal 44).

   Some property values are defined in terms of multiple components. parts. These
   structured property values MUST have their components value parts separated by a
   SEMICOLON character (ASCII (US-ASCII decimal 59).

   Lists of property parameters MAY be specified for

   Some properties allow a property. list of parameters. Each property parameter
   in a list of property parameters MUST be separated by a SEMICOLON
   character (ASCII (US-ASCII decimal 59).

   Property parameters with values containing a COLON, a SEMICOLON or a
   COMMA character must MUST be placed in quoted text string. text.

   For example, in the following properties a SEMICOLON is used to
   separate property parameters and property value fields. A COMMA is
   used to separate values.

     ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO:
      jsmith@host.com

     RDATE;VALUE=DATE:19970304,19970504,19970704,19970904

4.1.2   Multiple Values

   Some properties defined in the iCalendar object MAY can have multiple
   values. The general rule for encoding multi-valued items is to simply

Dawson/Stenerson                   15             Expires November 1998
   create a new content line for each value; value, including the property
   name. However, it should be noted that some properties support
   encoding multiple values in a single property by separating the
   values with a COMMA character (ASCII (US-ASCII decimal 44).

Dawson/Stenerson                   14            Expires September 1998 Individual
   property definitions should be consulted for determining whether a
   specific property allows multiple values and in which of these two
   forms.

4.1.3   Binary Content

   Binary content information in an iCalendar object SHOULD be
   referenced using a URI within a property value. That is the binary
   content information SHOULD be placed in an external MIME entity that
   can be referenced by a URI from within the iCalendar object. In
   applications where this is not feasible, binary content information
   MAY
   can be included within an iCalendar object, but only after first
   encoding it into text using the "B" "BASE64" encoding method defined in
   [RFC
   2047]. 2045]. Support for inline binary content SHOULD be restricted to
   those applications requirements that necessitate conveying the
   complete calendaring and scheduling information within a single
   iCalendar object. A property containing inline binary content
   information MUST specify the "ENCODING" property parameter. Binary
   content information placed external to the iCalendar object MUST be
   referenced by a uniform resource identifier (URI).

   The following example specifies an "ATTACH" property that references
   an attachment external to the iCalendar object with a URI reference:

     ATTACH:http://xyz.com/public/quarterly-report.doc

   The following example specifies an "ATTACH" property with inline
   binary encoded content information:

     ATTACH;ENCODING=b;VALUE=binary:MIICajCCAdOgAwIBAgICBEUwDQYJKoZI
      hvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENv
      bW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlv
      biBTeXN0

     ATTACH;ENCODING=BASE64;VALUE=BINARY:MIICajCCAdOgAwIBAgICBEUwD
      QYJKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjY
      XBlIENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvc
        <...remainder of "B" "BASE64" encoded binary data...>

4.1.4   Character Set

   There is not a property parameter to declare the character set used
   in a property value. The default character set for an iCalendar
   object is [UTF-8]. UTF-8 as defined in [RFC 2279].

   The "charset" Content-Type parameter MAY can be used in MIME transports
   to specify any other IANA registered character set.

4.2 Property Parameters

   A property MAY can have additional attributes associated with it. These "property
   parameters" contain meta information meta-information about the property or the
   property value. Property parameters MAY be used are provided to specify such
   information as the location of an alternate text representation for a

Dawson/Stenerson                   16             Expires November 1998
   property value, the language of a text property value or value, the data type
   of the property value. In addition, individual properties MAY define
   property-specific parameters that apply only to that property. value and other attributes.

   Property parameter values that contain the COLON, SEMICOLON, COMMA COLON (US-ASCII decimal
   58), SEMICOLON (US-ASCII decimal 59) or
   BACKSLASH COMMA (US-ASCII decimal 44)
   character separators MUST be specified as quoted-string text values.
   Property parameter values MUST NOT contain the DOUBLE-QUOTE (US-ASCII
   decimal 22) character. The DOUBLE-QUOTE (US-ASCII decimal 22)
   character is used as a delimiter for parameter values that contain
   restricted characters or URI text. For example:

Dawson/Stenerson                   15            Expires September 1998

     DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards
       Conference - - Las Vegas, NV, USA

   Property parameter values that are not in quoted strings are case
   insensitive.

   The general property parameters defined by this memo are specified defined by
   the following notation:

     parameter  = altrepparm            ;Alternate altrepparam           ; Alternate text representation
                / encodingparm          ;Inline cnparam               ; Common name
                / cutypeparam           ; Calendar user type
                / delfromparam          ; Delegator
                / deltoparam            ; Delegatee
                / dirparam              ; Directory entry
                / encodingparam         ; Inline encoding
                / languageparm          ;National language fbtypeparam           ; Free/busy time type
                / languageparam         ; Language for text
                / tzidparm              ;Reference memberparam           ; Group or list membership
                / partstatparam         ; Participation status
                / rangeparam            ; Recurrence identifier range
                / trigrelparam          ; Alarm trigger relationship
                / reltypeparam          ; Relationship type
                / roleparam             ; Participation role
                / rsvpparam             ; RSVP expectation
                / sentbyparam           ; Sent by
                / tzidparam             ; Reference to time zone object
                / valuetypeparm         ;Property valuetypeparam        ; Property value data type
                / iana-token
        ;Some ianaparam
        ; Some other IANA registered iCalendar parameter, such as those
        ;defined by an individual property. parameter.
                / x-name
        ;A xparam
        ; A non-standard, experimental parameter parameter.

     ianaparam  = iana-token "=" param-value *("," param-value)

     xparam     =x-name "=" param-value *("," param-value)

4.2.1   Alternate Text Representation

   Parameter Name: ALTREP

   Purpose: To specify an alternate text representation for the property
   value.

   Conformance: Optional

Dawson/Stenerson                   17             Expires November 1998
   Format Definition: The property parameter is defined by the following
   notation:

     altrepparm

     altrepparam        = "altrep" "ALTREP" "=" DQUOTE uri DQUOTE

   Description: The parameter specifies a URI that points to an
   alternate representation for a textual property value. A property
   specifying this parameter MUST also include a value that reflects the
   default representation.

   This property parameter MAY include multiple values, separated by representation of the
   COMMA character (ASCII decimal 44). text value. The property individual URI
   parameter MAY only values MUST be specified in the "COMMENT", "CONTACT", "DESCRIPTION", "LOCATION"
   and "SUMMARY" properties. a quoted-string.

   Example:

     DESCRIPTION;ALTREP="CID:<part3.msg.970415T083000@host.com>":Project
       XYZ Review Meeting will include the following agenda items: (a)
       Market Overview, (b) Finances, (c) Project Management

   The "ALTREP" property parameter value might point to a "text/html"
   content portion.

Dawson/Stenerson                   16            Expires September 1998

     Content-Type:text/html
     Content-Id:<part3.msg.970415T083000@host.com>

     <html><body>
     <p><b>Project XYZ Review Meeting</b> will include the following
     agenda items:<li>Market
     Overview</li><li>Finances</li><li>Project Management</li></p>
     </html></body>

4.2.2   Inline Encoding   Common Name

   Parameter Name: ENCODING CN

   Purpose: To specify an alternate inline encoding for the property
   value.

   Conformance: Required, if common name to be associated with the inline encoding is not "8bit".
   calendar user specified by the property.

   Format Definition: The property parameter is defined by the following
   notation:

     encodingparm

     cnparam    = "encoding" "CN" "=" "8bit"
        ;"8bit" text encoding is defined in [RFC 2045]
                        / "b"
        ;"b" binary encoding format is defined in [RFC 2047]
                        / iana-token
        ;Some other IANA registered iCalendar encoding type
                        / x-name
        ;A non-standard, experimental encoding type param-value

   Description: The "ENCODING property This parameter is an OPTIONAL property
   parameter. It identifies the inline encoding used in can be specified on properties with a property
   value.
   CAL-ADDRESS value type. The default encoding type is "8bit", corresponding parameter specifies the common name to a
   property be
   associated with the calendar user specified by the property. The
   parameter value consisting of is text. The "b" encoding type corresponds
   to a property parameter value encoded using the "B" encoding defined in [RFC
   2047].

   If the value type parameter is ";VALUE=BINARY", then the inline
   encoding parameter MUST can be specified used for display
   text to be associated with the value ";ENCODING=B". calendar address specified by the
   property.

   Example:

     ORGANIZER;CN="John Smith":MAILTO:jsmith@host.com

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4.2.3   Language   Calendar User Type

   Parameter Name: LANGUAGE CUTYPE

   Purpose: To specify the national language for text values in a
   property or property parameter.

   Conformance: Optional. There is no default national language for a
   text value. type of calendar user specified by the
   property.

   Format Definition: The property parameter is defined by the following
   notation:

     languageparm

     cutypeparam        =     "language" "CUTYPE" "=" language

     language = <Text identifying a language, as defined in [RFC 1766]>

Dawson/Stenerson                   17            Expires September 1998
                         ("INDIVIDUAL"          ; An individual
                        / "GROUP"               ; A group of individuals
                        / "RESOURCE"            ; A physical resource
                        / "ROOM"                ; A room resource
                        / "UNKNOWN"             ; Otherwise not known
                        / x-name                ; Experimental type
                        / iana-token)           ; Other IANA registered
                                                ; type
     ; Default is INDIVIDUAL

   Description: This parameter can be specified on properties with a
   CAL-ADDRESS value type. The parameter identifies the national language of the
   text in the property or property parameter value. The value type of calendar
   user specified by the
   "language" property. If not specified on a property parameter is that defined in [RFC 1766].

        Note: For transport in a MIME entity, the Content-Language
        header field MAY be used to set
   allows this parameter, the default language for the
        entire body part. is INDIVIDUAL.

   Example:

     SUMMARY;LANGUAGE=us-EN:Company Holiday Party

     ATTENDEE;CN=Henri Weisz;LANGUAGE=ca-FR:hweisz@host.com

     ATTENDEE;CUTYPE=GROUP:MAILTO:ietf-calsch@imc.org

4.2.4   Time Zone Identifier   Delegators

   Parameter Name: TZID DELEGATED-FROM

   Purpose: To specify the identifier for calendar users that have delegated their
   participation to the time zone definition for a
   time value.

   Conformance: Optional calendar user specified by the property.

   Format Definition: This The property parameter is defined by the following
   notation:

     tzidparm

     delfromparam       = "TZID" "DELEGATED-FROM" "=" [tzidprefix] paramtext CRLF

     tzidprefix = "/" DQUOTE cal-address DQUOTE
                          *("," DQUOTE cal-address DQUOTE)

   Description: The This parameter MAY only can be used specified on the "DTSTART",
   "DTEND", "DUE", "EXDATE" and "RDATE " properties when either with a DATE-
   TIME or TIME
   CAL-ADDRESS value type is specified. type. This property parameter
   specifies can be specified on a property
   that has a text value which uniquely identifies the "VTIMEZONE" type of calendar component address. This parameter specifies
   those calendar uses that have delegated their participation in a
   group scheduled event or to-do to be used when evalating the time portion of calendar user specified by the
   property. The value of the TZID property parameter will MUST be equal to
   the value of the TZID property for the matching "TIMEZONE" object.
   The presence of the SOLIDUS character (ASCII decimal 47) as a prefix,
   indicates that this TZID represents a unique ID in a globally MAILTO URI as defined
   time zone registry (when such registry is defined).

   The following are examples of this property parameter:

     DTSTART;TZID=America-New_York:19980119T020000

     DTEND;TZID=America-New_York:19980119T030000 in [RFC 1738].
   The TZID property individual URI parameter values MUST NOT be applied to DATE-TIME nor TIME
   properties whose time values are specified in UTC.

   The use of local time in a DATE-TIME or TIME value without the TZID
   property parameter is to be interpreted as a local time value,
   regardless of the existence of "VTIMEZONE" calendar components in the
   iCalendar object. quoted-
   string.

   Example:

Dawson/Stenerson                   18                   19             Expires September November 1998
   For more information see the sections on the data types DATE-TIME and
   TIME.
     ATTENDEE;DELEGATED-FROM="MAILTO:jsmith@host.com":MAILTO:
      jdoe@host.com

4.2.5   Value Data Types   Delegatees

   Parameter Name: VALUE DELEGATED-TO

   Purpose: To explicitly specify the data type format for a property
   value.

   Conformance: Optional if using calendar users whom the calendar user
   specified by the default value type in a property
   value. Otherwise, it is required. has delegated participation to.

   Format Definition: The "VALUE" property parameter is defined by the following
   notation:

     valuetypeparm

     deltoparam = "value" "DELEGATED-TO" "=" valuetype

     valuetype  = "binary"
                / "boolean"
                / "cal-address"
                / "date"
                / "date-time"
                / "duration"
                / "float"
                / "integer"
                / "period"
                / "recur"
                / "text"
                / "time"
                / "uri"
                / "utc-offset"
                / x-name
                        ;Some experimental iCalendar data type.
                / iana-token
                        ;Some other IANA registered iCalendar data type. DQUOTE cal-address DQUOTE
                  *("," DQUOTE cal-address DQUOTE)

   Description: The This parameter is used to identify the data type and
   format of the property value. The property values MUST can be of specified on properties with a single
   CAL-ADDRESS value type. For example, a "RDATE" property cannot This parameter specifies those calendar users
   whom have a combination
   of DATE-TIME and TIME value types.

4.3 Property Value Data Types

   The properties in an iCalendar object are strongly typed. The
   definition of each property restricts the value to be one of the
   value data types, or simply value types, defined been delegated participation in this section. The
   value type for a property will either be specified implicitly as the
   default value type group scheduled event or will be explicitly specified with
   to-do by the "VALUE"
   parameter. If calendar user specified by the property. The value type of MUST
   be a property is one of the alternate
   valid types, then it MAILTO URI as defined in [RFC 1738]. The individual URI
   parameter values MUST be explicitly specified with the "VALUE"
   parameter.

Dawson/Stenerson                   19            Expires September 1998

4.3.1   Binary

   Value in a quoted-string.

   Example:

     ATTENDEE;DELEGATED-TO="MAILTO:jdoe@host.com","MAILTO:jqpublic@
      host.com":MAILTO:jsmith@host.com

4.2.6   Directory Entry Reference

   Parameter Name: BINARY DIR

   Purpose: This value type is used To specify reference to identify properties that contain a character encoding of inline binary data. For example, an inline
   attachment of an object code MAY BE included in an iCalendar object.

   Formal directory entry associated with
   the calendar user specified by the property.

   Format Definition: The value type property parameter is defined by the following
   notation:

     binary

     dirparam   = *(4b-char) [b-end]
     ; A "B" encoded character string, as defined by [RFC 2047].

     b-end      = (2b-char "==") / (3b-char "=")

     b-char = ALPHA / DIGIT / "+" / "/" "DIR" "=" DQUOTE uri DQUOTE

   Description: Property values with this value type MUST also include
   the inline encoding This parameter sequence of ";ENCODING=B". That is, all
   inline binary data MUST first can be character encoded using the "B"
   encoding method defined in [RFC 2047]. No additional content value
   encoding (i.e., BACKSLASH character encoding) is defined for this specified on properties with a
   CAL-ADDRESS value type.

   Example: The following is an abridged example of parameter specifies a "B" encoded binary
   value data.

     ATTACH;VALUE=BINARY:MIICajCCAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQA
      wdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb
      25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlvbiBTeXN0
        <...remainder of "B" encoded binary data...>

4.3.2   Boolean

   Value Name: BOOLEAN

   Purpose: This value type is used reference to identify properties that contain
   either a "true" or "false" boolean value.

   Formal Definition: The value type is defind the
   directory entry associated with the calendar user specified by the following
   notation:

     boolean    = "TRUE" / "FALSE"

   Description: These values are case insensitive text. No additional
   content
   property. The parameter value encoding (i.e., BACKSLASH character encoding) is
   defined for this value type. a URI. The individual URI parameter
   values MUST be specified in a quoted-string.

   Example: For example, any of the following are equivalent:

     TRANSP;VALUE=BOOLEAN:TRUE
     TRANSP;VALUE=BOOLEAN:true
     TRANSP;VALUE=BOOLEAN:TrUe

     ORGANIZER;DIR="ldap://host.com:6666/o=eDABC%20Industries,c=3DUS??
      (cn=3DBJim%20Dolittle)":MAILTO:jimdo@host1.com

4.2.7   Inline Encoding

   Parameter Name: ENCODING

Dawson/Stenerson                   20             Expires September November 1998

4.3.3   Calendar User Address

   Value Name: CAL-ADDRESS
   Purpose: This value type is used to identify properties that contain
   a calendar user address.

   Formal To specify an alternate inline encoding for the property
   value.

   Format Definition: The value type property parameter is as defined by the following
   notation:

     cal-address

     encodingparam      = uri

   Description: The value "ENCODING" "="
                          ("8BIT"
        ; "8bit" text encoding is a URI as defined by in [RFC 1738] or any other
   IANA 2045]
                        / "BASE64"
        ; "BASE64" binary encoding format is defined in [RFC 2045]
                        / iana-token
        ; Some other IANA registered form for a URI. When iCalendar encoding type
                        / x-name)
        ; A non-standard, experimental encoding type

   Description: The property parameter identifies the inline encoding
   used in a property value. The default encoding is "8BIT",
   corresponding to address an Internet
   email transport address for a calendar user, the property value MUST be consisting of text. The "BASE64"
   encoding type corresponds to a
   MAILTO URI, as property value encoded using the
   "BASE64" encoding defined by in [RFC 1738].No additional content 2045].

   If the value
   encoding (i.e., BACKSLASH character encoding) type parameter is defined for this ";VALUE=BINARY", then the inline
   encoding parameter MUST be specified with the value type.
   ";ENCODING=BASE64".

   Example:

     ATTENDEE;VALUE=CAL-ADDRESS:MAILTO:jane_doe@host.com

4.3.4   Date

   Value

     ATTACH;ENCODING=BASE64;VALUE=BINARY:MIICajCCAdOgAwIBAgICBEUwD
      QYJKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjY
      XBlIENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvc
        <...remainder of "BASE64" encoded binary data...>

4.2.8   Free/Busy Time Type

   Parameter Name: DATE FBTYPE

   Purpose: This value type is used to identify values that contain a
   calendar date.

   Formal To specify the free or busy time type.

   Format Definition: The value type property parameter is defined by the following
   notation:

     date               = date-value *("," [WSP] date-value)

     date-value         = date-fullyear date-month date-mday
     date-fullyear      = 4DIGIT
     date-month         = 2DIGIT        ;01-12
     date-mday

     fbtypeparam        = 2DIGIT        ;01-28, 01-29, 01-30, 01-31
                                        ;based on month/year "FBTYPE" "=" ("FREE" / "BUSY"
                        / "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE"
                        / x-name
        ; Some experimental iCalendar data type.
                        / iana-token)
        ; Some other IANA registered iCalendar data type.

   Description: If the property permits, multiple "date" values MAY be
   specified using a COMMA character (ASCII decimal 44) separator
   character.The format for The parameter specifies the free or busy time type. The
   value type is expressed as FREE indicates that the [ISO
   8601] complete representation, basic format time interval is free for a calendar date. scheduling.
   The
   textual format specifies a four-digit year, two-digit month, and two-
   digit day of value BUSY indicates that the month. There are no separator characters between time interval is busy because one
   or more events have been scheduled for that interval. The value BUSY-
   UNAVAILABLE indicates that the
   year, month time interval is busy and day component text.

   No additional content that the

Dawson/Stenerson                   21             Expires November 1998
   interval can not be scheduled. The value encoding (i.e., BACKSLASH character
   encoding) BUSY-TENTATIVE indicates
   that the time interval is defined busy because one or more events have been
   tentatively scheduled for that interval. If not specified on a
   property that allows this value type. parameter, the default is BUSY.

   Example: The following represents July 14, 1997:

Dawson/Stenerson                   21            Expires September 1998
     19970714

4.3.5   Date-Time

   Value is an example of this parameter on a FREEBUSY
   property.

     FREEBUSY;FBTYPE=BUSY:19980415T133000Z/19980415T170000Z

4.2.9   Language

   Parameter Name: DATE-TIME LANGUAGE

   Purpose: This value type is used to identify values that To specify the language for text values in a
   precise calendar data and time of day.

   Formal property or
   property parameter.

   Format Definition: The value type property parameter is defined by the following
   notation:

     date-time

     languageparam = dt-value *("," [WSP] dt-value)

     dt-value    "LANGUAGE" "=" language

     language = date "T" time ;As specified above <Text identifying a language, as defined in date and time [RFC 1766]>

   Description: If the property permits, multiple "date-time" values MAY This parameter can be specified using on properties with a COMMA character (ASCII decimal 44) separator
   character. No additional content value encoding (i.e., BACKSLASH
   character encoding) is defined for this
   text value type. The "DATE-TIME" data type is used to identify values that contain a
   precise calendar date and time of day. The format is based on parameter identifies the
   [ISO 8601] complete representation, basic format for a calendar date
   and time language of day. The the text format is a concatenation of the "date",
   followed by the LATIN CAPITAL LETTER T character (ASCII decimal 84)
   time designator, followed by the "time" format.

   The "DATE-TIME" data type expresses time values in three forms:
   the property or property parameter value. The form value of date and time with UTC offset MUST NOT be used. For
   example, the following is not valid for a date-time value:

     DTSTART:19980119T230000-0800

   FORM #1: DATE WITH LOCAL TIME

   The date with local time form "language"
   property parameter is simply a date-time value that does
   not contain the UTC designator nor does it reference a time zone. defined in [RFC 1766].

   For
   example, transport in a MIME entity, the following represents Janurary 18, 1998, at 11 PM:

     DTSTART:19980118T230000

   Date-time values of this type are said to Content-Language header field can
   be "floating" and are not
   bound to any time zone in particular. They are used to represent set the
   same hour, minute, and second value regardless of which time zone is
   currently being observed. For example, an event MAY be defined that
   indicates that an individual will be busy from 11:00 AM to 1:00 PM
   every day, no matter which timezone default language for the person entire body part.
   Otherwise, no default language is in. In these cases,
   a local time MAY be specified. assumed.

   Example:

     SUMMARY;LANGUAGE=us-EN:Company Holiday Party

     LOCATION;LANGUAGE=en:Germany
     LOCATION;LANGUAGE=no:Tyskland

   The recipient of an iCalendar object
   with a property value consisting following example makes use of a local time, without any
   relative time zone information, should interpret the value as being
   fixed Quoted-Printable encoding in
   order to whatever timezone represent non-ASCII characters.

     LOCATION;LANGUAGE=da:K=F8benhavn
     LOCATION;LANGUAGE=en:Copenhagen

4.2.10  Group or List Membership

   Parameter Name: MEMBER

   Purpose: To specify the ATTENDEE is in at any given moment.
   This means that two ATTENDEEs may participate in group or list membership of the same event at calendar user
   specified by the property.

Dawson/Stenerson                   22             Expires September November 1998
   different UTC times; floating time should only be used where that is
   reasonable behavior.

   In most cases, a fixed time is desired. To properly communicate a
   fixed time in a property value, either UTC time or local time with
   time zone reference MUST be specified.
   Format Definition: The use of local time in a DATE-TIME value without the TZID property parameter is to defined by the following
   notation:

     memberparam        = "MEMBER" "=" DQUOTE cal-address DQUOTE
                          *("," DQUOTE cal-address DQUOTE)

   Description: This parameter can be interpreted as specified on properties with a local time value, regardless of
   CAL-ADDRESS value type. The parameter identifies the groups or list
   membership for the existence of "VTIMEZONE" calendar components in user specified by the iCalendar
   object.

   FORM #2: DATE WITH UTC TIME property. The date with UTC time,
   parameter value either a single calendar address in a quoted-string
   or absolute time, is identified by a LATIN
   CAPITAL LETTER Z suffix COMMA character (ASCII (US-ASCII decimal 90), the UTC
   designator, appended to the time value. For example, the following
   represents January 19, 1998, at 0700 UTC:

     DTSTART:19980119T070000Z 44) list of calendar
   addresses, each in a quoted-string. The TZID property individual calendar address
   parameter values MUST NOT be applied to DATE-TIME
   properties whose time values are specified in UTC.

   FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE a quoted-string.

   Example:

     ATTENDEE;MEMBER="MAILTO:ietf-calsch@imc.org":MAILTO:jsmith@host.com

     ATTENDEE;MEMBER="MAILTO:projectA@host.com","MAILTO:projectB@host.
      com":MAILTO:janedoe@host.com

4.2.11  Participation Status

   Parameter Name: PARTSTAT

   Purpose: To specify the participation status for the calendar user
   specified by the property.

   Format Definition: The date and local time with reference to time zone information property parameter is
   identified defined by the following
   notation:

     partstatparam      = "PARTSTAT" "="
                         ("NEEDS-ACTION"        ; Event needs action
                        / "ACCEPTED"            ; Event accepted
                        / "DECLINED"            ; Event declined
                        / "TENTATIVE"           ; Event tentatively
                                                ; accepted
                        / "DELEGATED"           ; Event delegated
                        / x-name                ; Experimental status
                        / iana-token)           ; Other IANA registered
                                                ; status
     ; These are the participation statuses for a "VEVENT". Default is
     ; NEEDS-ACTION

     partstatparam      /= "PARTSTAT" "="
                         ("NEEDS-ACTION"        ; To-do needs action
                        / "ACCEPTED"            ; To-do accepted
                        / "DECLINED"            ; To-do declined
                        / "TENTATIVE"           ; To-do tentatively
                                                ; accepted
                        / "DELEGATED"           ; To-do delegated
                        / "COMPLETED"           ; To-do completed.
                                                ; COMPLETED property has
                                                ;date/time completed.

Dawson/Stenerson                   23             Expires November 1998
                        / "IN-PROCESS"          ; To-do in process of
                                                ; being completed
                        / x-name                ; Experimental status
                        / iana-token)           ; Other IANA registered
                                                ; status
     ; These are the participation statuses for a "VTODO". Default is
     ; NEEDS-ACTION

     partstatparam      /= "PARTSTAT" "="
                         ("NEEDS-ACTION"        ; Journal needs action
                        / "ACCEPTED"            ; Journal accepted
                        / "DECLINED"            ; Journal declined
                        / x-name                ; Experimental status
                        / iana-token)           ; Other IANA registered
                                                ; status
     ; These are the participation statuses for a "VJOURNAL". Default is
     ; NEEDS-ACTION

4.2.12  Recurrence Identifier Range

   Parameter Name: RANGE

   Purpose: To specify the effective range of recurrence instances from
   the instance specified by the recurrence identifier specified by the
   property.

   Format Definition: The property parameter is defined by the following
   notation:

     rangeparam = "RANGE" "=" ("THISANDPRIOR"
        ; To specify all instances prior to the recurrence identifier
                / "THISANDFUTURE")
        ; To specify the instance specified by the recurrence identifier
        ; and all subsequent recurrence instances

   Description: The parameter can be specified on a property that
   specifies a recurrence identifier. The parameter specifies the
   effective range of recurrence instances that is specified by the
   property. The effective range is from the recurrence identified
   specified by the property. If this parameter is not specified an
   allowed property, then the default range is the single instance
   specified by the recurrence identifier value of the property. The
   parameter value can be "THISANDPRIOR" to indicate a range defined by
   the recurrence identified value of the property and all prior
   instances. The parameter value can also be "THISANDFUTURE" to
   indicate a range defined by the recurrence identifier and all
   subsequent instances.

   Example:

     RECURRENCE-ID;RANGE=THISANDPRIOR:19980401T133000Z

Dawson/Stenerson                   24             Expires November 1998

4.2.13  Alarm Trigger Relationship

   Parameter Name: RELATED

   Purpose: To specify the relationship of the alarm trigger with
   respect to the start or end of the calendar component.

   Format Definition: The property parameter is defined by the following
   notation:

     trigrelparam       = "RELATED" "="
                         ("START"       ; Trigger off of start
                        / "END")        ; Trigger off of end

   Description: The parameter can be specified on properties that
   specify an alarm trigger with a DURATION value type. The parameter
   specifies whether the alarm will trigger relative to the start or end
   of the calendar component. The parameter value START will set the
   alarm to trigger off the start of the calendar component; the
   parameter value END will set the alarm to trigger off the end of the
   calendar component. If the parameter is not specified on an allowable
   property, then the default is START.

   Example:

     TRIGGER;RELATED=END:PT5M

4.2.14  Relationship Type

   Parameter Name: RELTYPE

   Purpose: To specify the type of hierarchical relationship associated
   with the calendar component specified by the property.

   Format Definition: The property parameter is defined by the following
   notation:

     reltypeparam       = "RELTYPE" "="
                         ("PARENT"      ; Parent relationship. Default.
                        / "CHILD"       ; Child relationship
                        / "SIBLING      ; Sibling relationship
                        / iana-token    ; Some other IANA registered
                                        ; iCalendar relationship type
                        / x-name)       ; A non-standard, experimental
                                        ; relationship type

   Description: This parameter can be specified on a property that
   references another related calendar. The parameter specifies the
   hierarchical relationship type of the calendar component referenced
   by the property. The parameter value can be PARENT, to indicate that
   the referenced calendar component is a superior of calendar
   component; CHILD to indicate that the referenced calendar component
   is a subordinate of the calendar component; SIBLING to indicate that
   the referenced calendar component is a peer of the calendar

Dawson/Stenerson                   25             Expires November 1998
   component. If this parameter is not specified on an allowable
   property, the default relationship type is PARENT.

   Example:

     RELATED-TO;RELTYPE=SIBLING:<19960401-080045-4000F192713@host.com>

   Description: This parameter can be specified on properties with a
   CAL-ADDRESS value type. The parameter identifies the participation
   status for the calendar user specified by the property value. The
   parameter values differ depending on whether they are associated with
   a group scheduled "VEVENT", "VTODO" or "VJOURNAL". The values MUST
   match one of the values allowed for the given calendar component. If
   not specified on a property that allows this parameter, the default
   value is NEEDS-ACTION.

   Example:

     ATTENDEE;PARTSTAT=DECLINED:MAILTO:jsmith@host.com

4.2.15  Participation Role

   Parameter Name: ROLE

   Purpose: To specify the participation role for the calendar user
   specified by the property.

   Format Definition: The property parameter is defined by the following
   notation:

     roleparam  = "ROLE" "="
                 ("CHAIR"               ; Indicates chair of the
                                        ; calendar entity
                / "REQ-PARTICIPANT"     ; Indicates a participant whose
                                        ; participation is required
                / "OPT-PARTICIPANT"     ; Indicates a participant whose
                                        ; participation is optional
                / "NON-PARTICIPANT"     ; Indicates a participant who is
                                        ; copied for information
                                        ; purposes only
                / x-name                ; Experimental role
                / iana-token)           ; Other IANA role
     ; Default is REQ-PARTICIPANT

   Description: This parameter can be specified on properties with a
   CAL-ADDRESS value type. The parameter specifies the participation
   role for the calendar user specified by the property in the group
   schedule calendar component. If not specified on a property that
   allows this parameter, the default value is REQ-PARTICIPANT.

   Example:

     ATTENDEE;ROLE=CHAIR:MAILTO:mrbig@host.com

Dawson/Stenerson                   26             Expires November 1998

4.2.16  RSVP Expectation

   Parameter Name: RSVP

   Purpose: To specify whether there is an expectation of a favor of a
   reply from the calendar user specified by the property value.

   Format Definition: The property parameter is defined by the following
   notation:

     rsvpparam = "RSVP" "=" ("TRUE" / "FALSE")
     ; Default is FALSE

   Description: This parameter can be specified on properties with a
   CAL-ADDRESS value type. The parameter identifies the expectation of a
   reply from the calendar user specified by the property value. This
   parameter is used by the "Organizer" to request a participation
   status reply from an "Attendee" of a group scheduled event or to-do.
   If not specified on a property that allows this parameter, the
   default value is FALSE.

   Example:

     ATTENDEE;RSVP=TRUE:MAILTO:jsmith@host.com

4.2.17  Sent By

   Parameter Name: SENT-BY

   Purpose: To specify the calendar user that is acting on behalf of the
   calendar user specified by the property.

   Format Definition: The property parameter is defined by the following
   notation:

     sentbyparam        = "SENT-BY" "=" DQUOTE cal-address DQUOTE

   Description: This parameter can be specified on properties with a
   CAL-ADDRESS value type. The parameter specifies the calendar user
   that is acting on behalf of the calendar user specified by the
   property. The parameter value MUST be a MAILTO URI as defined in [RFC
   1738]. The individual URI parameter values MUST be specified in a
   quoted-string.

   Example:

     ORGANIZER;SENT-BY:"MAILTO:sray@host.com":MAILTO:jsmith@host.com

4.2.18  Time Zone Identifier

   Parameter Name: TZID

   Purpose: To specify the identifier for the time zone definition for a
   time component in the property value.

Dawson/Stenerson                   27             Expires November 1998
   Format Definition: This property parameter is defined by the
   following notation:

     tzidparam  = "TZID" "=" [tzidprefix] paramtext CRLF

     tzidprefix = "/"

   Description: The parameter MUST be specify on the "DTSTART", "DTEND",
   "DUE", "EXDATE" and "RDATE" properties when either a DATE-TIME or
   TIME value type is specified and when the value is not either a UTC
   or a "floating" time. This property parameter specifies a text value
   which uniquely identifies the "VTIMEZONE" calendar component to be
   used when evaluating the time portion of the property. The value of
   the TZID property parameter will be equal to the value of the TZID
   property for the matching time zone definition. An individual
   "VTIMEZONE" calendar component MUST be specified for each unique
   "TZID" parameter value specified in the iCalendar object.

   The parameter MUST be specified on properties with a DATE-TIME value
   if the DATE-TIME is not either a UTC or a "floating" time.

   The presence of the SOLIDUS character (US-ASCII decimal 47) as a
   prefix, indicates that this TZID represents a unique ID in a globally
   defined time zone registry (when such registry is defined).

   The following are examples of this property parameter:

     DTSTART;TZID=America-New_York:19980119T020000

     DTEND;TZID=America-New_York:19980119T030000

   The TZID property parameter MUST NOT be applied to DATE-TIME or TIME
   properties whose time values are specified in UTC.

   The use of local time in a DATE-TIME or TIME value without the TZID
   property parameter is to be interpreted as a local time value,
   regardless of the existence of "VTIMEZONE" calendar components in the
   iCalendar object.

   For more information see the sections on the data types DATE-TIME and
   TIME.

4.2.19  Value Data Types

   Parameter Name: VALUE

   Purpose: To explicitly specify the data type format for a property
   value.

   Format Definition: The "VALUE" property parameter is defined by the
   following notation:

     valuetypeparam = "VALUE" "=" valuetype

Dawson/Stenerson                   28             Expires November 1998
     valuetype  = ("BINARY"
                / "BOOLEAN"
                / "CAL-ADDRESS"
                / "DATE"
                / "DATE-TIME"
                / "DURATION"
                / "FLOAT"
                / "INTEGER"
                / "PERIOD"
                / "RECUR"
                / "TEXT"
                / "TIME"
                / "URI"
                / "UTC-OFFSET"
                / x-name
                ; Some experimental iCalendar data type.
                / iana-token)
                ; Some other IANA registered iCalendar data type.

   Description: The parameter specifies the data type and format of the
   property value. The property values MUST be of a single value type.
   For example, a "RDATE" property cannot have a combination of DATE-
   TIME and TIME value types.

   If the property's value is the default value type, then this
   parameter need not be specified. However, if the property's default
   value type is overridden by some other allowable value type, then
   this parameter MUST be specified.

4.3 Property Value Data Types

   The properties in an iCalendar object are strongly typed. The
   definition of each property restricts the value to be one of the
   value data types, or simply value types, defined in this section. The
   value type for a property will either be specified implicitly as the
   default value type or will be explicitly specified with the "VALUE"
   parameter. If the value type of a property is one of the alternate
   valid types, then it MUST be explicitly specified with the "VALUE"
   parameter.

4.3.1   Binary

   Value Name: BINARY

   Purpose: This value type is used to identify properties that contain
   a character encoding of inline binary data. For example, an inline
   attachment of an object code might be included in an iCalendar
   object.

   Formal Definition: The value type is defined by the following
   notation:

     binary     = *(4b-char) [b-end]
     ; A "BASE64" encoded character string, as defined by [RFC 2045].

Dawson/Stenerson                   29             Expires November 1998
     b-end      = (2b-char "==") / (3b-char "=")

     b-char = ALPHA / DIGIT / "+" / "/"

   Description: Property values with this value type MUST also include
   the inline encoding parameter sequence of ";ENCODING=BASE64". That
   is, all inline binary data MUST first be character encoded using the
   "BASE64" encoding method defined in [RFC 2045]. No additional content
   value encoding (i.e., BACKSLASH character encoding) is defined for
   this value type.

   Example: The following is an abridged example of a "BASE64" encoded
   binary value data.

     ATTACH;VALUE=BINARY;ENCODING=BASE64:MIICajCCAdOgAwIBAgICBEUwDQY
      JKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlI
      ENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZv
        <...remainder of "BASE64" encoded binary data...>

4.3.2   Boolean

   Value Name: BOOLEAN

   Purpose: This value type is used to identify properties that contain
   either a "TRUE" or "FALSE" Boolean value.

   Formal Definition: The value type is defind by the following
   notation:

     boolean    = "TRUE" / "FALSE"

   Description: These values are case insensitive text. No additional
   content value encoding (i.e., BACKSLASH character encoding) is
   defined for this value type.

   Example: The following is an example of a hypothetical property that
   has a BOOLEAN value type:

   GIBBERISH:TRUE

4.3.3   Calendar User Address

   Value Name: CAL-ADDRESS

   Purpose: This value type is used to identify properties that contain
   a calendar user address.

   Formal Definition: The value type is as defined by the following
   notation:

     cal-address        = uri

   Description: The value is a URI as defined by [RFC 1738] or any other
   IANA registered form for a URI. When used to address an Internet

Dawson/Stenerson                   30             Expires November 1998
   email transport address for a calendar user, the value MUST be a
   MAILTO URI, as defined by [RFC 1738]. No additional content value
   encoding (i.e., BACKSLASH character encoding) is defined for this
   value type.

   Example:

     ATTENDEE:MAILTO:jane_doe@host.com

4.3.4   Date

   Value Name: DATE

   Purpose: This value type is used to identify values that contain a
   calendar date.

   Formal Definition: The value type is defined by the following
   notation:

     date               = date-value

     date-value         = date-fullyear date-month date-mday
     date-fullyear      = 4DIGIT
     date-month         = 2DIGIT        ;01-12
     date-mday          = 2DIGIT        ;01-28, 01-29, 01-30, 01-31
                                        ;based on month/year

   Description: If the property permits, multiple "date" values can be
   specified using a COMMA character (US-ASCII decimal 44) separator
   character. The format for the value type is expressed as the [ISO
   8601] complete representation, basic format for a calendar date. The
   textual format specifies a four-digit year, two-digit month, and two-
   digit day of the month. There are no separator characters between the
   year, month and day component text.

   No additional content value encoding (i.e., BACKSLASH character
   encoding) is defined for this value type.

   Example: The following represents July 14, 1997:

     19970714

4.3.5   Date-Time

   Value Name: DATE-TIME

   Purpose: This value type is used to identify values that specify a
   precise calendar date and time of day.

   Formal Definition: The value type is defined by the following
   notation:

     date-time  = date "T" time ;As specified in the date and time
                                ;value definitions

Dawson/Stenerson                   31             Expires November 1998
   Description: If the property permits, multiple "date-time" values MAY
   be specified using a COMMA character (US-ASCII decimal 44) separator
   character. No additional content value encoding (i.e., BACKSLASH
   character encoding) is defined for this value type.

   The "DATE-TIME" data type is used to identify values that contain a
   precise calendar date and time of day. The format is based on the
   [ISO 8601] complete representation, basic format for a calendar date
   and time of day. The text format is a concatenation of the "date",
   followed by the LATIN CAPITAL LETTER T character (US-ASCII decimal
   84) time designator, followed by the "time" format.

   The "DATE-TIME" data type expresses time values in three forms:

   The form of date and time with UTC offset MUST NOT be used. For
   example, the following is not valid for a date-time value:

     DTSTART:19980119T230000-0800       ;Invalid time format

   FORM #1: DATE WITH LOCAL TIME

   The date with local time form is simply a date-time value that does
   not contain the UTC designator nor does it reference a time zone. For
   example, the following represents Janurary 18, 1998, at 11 PM:

     DTSTART:19980118T230000

   Date-time values of this type are said to be "floating" and are not
   bound to any time zone in particular. They are used to represent the
   same hour, minute, and second value regardless of which time zone is
   currently being observed. For example, an event can be defined that
   indicates that an individual will be busy from 11:00 AM to 1:00 PM
   every day, no matter which time zone the person is in. In these
   cases, a local time can be specified. The recipient of an iCalendar
   object with a property value consisting of a local time, without any
   relative time zone information, should interpret the value as being
   fixed to whatever time zone the ATTENDEE is in at any given moment.
   This means that two ATTENDEEs, in different time zones, receiving the
   same event definition as a floating time, may be participating in the
   event at different actual times. Floating time should only be used
   where that is the reasonable behavior.

   In most cases, a fixed time is desired. To properly communicate a
   fixed time in a property value, either UTC time or local time with
   time zone reference MUST be specified.

   The use of local time in a DATE-TIME value without the TZID property
   parameter is to be interpreted as floating time, regardless of the
   existence of "VTIMEZONE" calendar components in the iCalendar object.

   FORM #2: DATE WITH UTC TIME

   The date with UTC time, or absolute time, is identified by a LATIN
   CAPITAL LETTER Z suffix character (US-ASCII decimal 90), the UTC

Dawson/Stenerson                   32             Expires November 1998
   designator, appended to the time value. For example, the following
   represents January 19, 1998, at 0700 UTC:

     DTSTART:19980119T070000Z

   The TZID property parameter MUST NOT be applied to DATE-TIME
   properties whose time values are specified in UTC.

   FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE

   The date and local time with reference to time zone information is
   identified by the use the TZID property parameter to reference the
   appropriate time zone definition. TZID is discussed in detail in the
   section on Time Zone. For example, the following represents 2 AM in
   New York on Janurary 19, 1998:

          DTSTART;TZID=America-New_York:19980119T020000

   Example: The following represents July 14, 1997, at 1:30 PM in New
   York City in each of the three time formats, using the "DTSTART"
   property.

     DTSTART:19970714T133000            ;Local time
     DTSTART:19970714T153000Z
     DTSTART:19970714T173000Z           ;UTC time
     DTSTART;TZID=America-NYC:19970714T133000   ;Local time and time
                        ; zone reference

   A time value MUST ONLY specify 60 seconds when specifying the
   periodic "leap second" in the time value. For example:

     COMPLETED:19970630T235960Z

4.3.6   Duration

   Value Name: DURATION

   Purpose: This value type is used to identify properties that contain
   a duration of time.

   Formal Definition: The value type is defined by the following
   notation:

     duration   = dur-value *("," [WSP] dur-value)

Dawson/Stenerson                   23            Expires September 1998
     dur-value  = (["+"] / "-") "P" (dur-date / dur-time / dur-week)

     dur-date   = (dur-day) dur-day [dur-time]
     dur-time   = "T" (dur-hour / dur-minute / dur-second)
     dur-week   = 1*DIGIT "W"
     dur-hour   = 1*DIGIT "H" [dur-minute]
     dur-minute = 1*DIGIT "M" [dur-second]
     dur-second = 1*DIGIT "S"
     dur-day    = 1*DIGIT "D"

   Description: If the property permits, multiple "duration" values MAY can
   be specified using a COMMA character (ASCII (US-ASCII decimal 44) separator
   character.The

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   character. The format is expressed as the [ISO 8601] basic format for
   the duration of time. The format can represent durations in terms of
   years, months,
   weeks, days, hours, minutes, and seconds.

   No additional content value encoding (i.e., BACKSLASH character
   encoding) are defined for this value type.

   Example: A duration of 15 days, 5 hours, 30 minutes hours and 20 seconds would be:

     P15DT5H30M20S

     P15DT5H0M20S

   A duration of 7 weeks would be:

     P15DT5H30M20S

     P7W

4.3.7   Float

   Value Name: FLOAT

   Purpose: This value type is used to identify properties that contain
   a real value number value.

   Formal Definition: The value type is defined by the following
   notation:

     float      = float-value *("," [WSP] float-value)

     float-value = (["+"] / "-") 1*DIGIT ["." 1*DIGIT]

   Description: If the property permits, multiple "float" values MAY can be
   specified using a COMMA character (ASCII (US-ASCII decimal 44) separator
   character.

   No additional content value encoding (i.e., BACKSLASH character
   encoding) is defined for this value type.

   Example:

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     1000000.0000001
     1.333
     -3.14

4.3.8   Integer

   Value Name:INTEGER

   Purpose: This value type is used to identify properties that contain
   a signed integer value.

   Formal Definition: The value type is defined by the following
   notation:

     integer    = integer-value *("," [WSP] integer-value)

     integer-value = (["+"] / "-") *DIGIT 1*DIGIT

   Description: If the property permits, multiple "integer" values MAY can
   be specified using a COMMA character (ASCII (US-ASCII decimal 44) separator
   character.The

Dawson/Stenerson                   34             Expires November 1998
   character. The valid range for "integer" is -2147483648 to
   2147483647. If the sign is not specified, then the value is assumed
   to be positive. If the property permits, multiple "integer" values MAY
   can be specified using a COMMA character (ASCII (US-ASCII decimal 44)
   separator character.

   No additional content value encoding (i.e., BACKSLASH character
   encoding) is defined for this value type.

   Example:

     1234567890
     -1234567890
     +1234567890
     432109876

4.3.9   Period of Time

   Value Name: PERIOD

   Purpose: This value type is used to identify values that contain a
   precise period of time.

   Formal Definition: The data type is defined by the following
   notation:

     period     = period-value *("," [WSP] period-value)

     period-value = period-explicit / period-start

     period-explicit = date-time "/" date-time
     ;ISO 8601
     ; [ISO 8601] complete representation basic format for a period of
     ; time
     ;consisting consisting of a start and end. The start MUST be before the
     ; end.

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     period-start = date-time "/" duration
     ;ISO 8601
     ; [ISO 8601] complete representation basic format for a period of
     ; time
     ;consisting consisting of a start and positive duration of time.

   Description: If the property permits, multiple "period" values MAY can be
   specified using a COMMA character (ASCII (US-ASCII decimal 44) separator
   character. There are two forms of a period of time. A period of time
   MAY be
   is identified by it's its start and it's its end. This format is expressed as
   the [ISO 8601] complete representation, basic format for "DATE-TIME"
   start of the period, followed by a SOLIDUS character
   (ASCII (US-ASCII
   decimal 47), followed by the "DATE-TIME" of the end of the period.
   The start of the period MUST be before the end of the period. A
   period of time MAY can also be defined by a start and a positive duration
   of time. The format is expressed as the [ISO 8601] complete
   representation, basic format for the "DATE-TIME" start of the period,
   followed by a SOLIDUS character (ASCII (US-ASCII decimal 47), followed by
   the [ISO 8601] basic format for "DURATION" of the period.

   Example: The period starting at 18:00:00 UTC, on January 1, 1997 and
   ending at 07:00:00 UTC on January 2, 1997 would be:

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     19970101T180000Z/19970102T070000Z

   The period start at 18:00:00 on January 1, 1997 and lasting 5 hours
   and 30 minutes would be:

     19970101T180000Z/PT5H30M

   No additional content value encoding (i.e., BACKSLASH character
   encoding) is defined for this value type.

4.3.10  Recurrence Rule

   Value Name: RECURR RECUR

   Purpose: This value type is used to identify properties that contain
   a recurrence rule specification.

   Formal Definition: The value type is defined by the following
   notation:

     recur      = recur-value *("," [WSP] recur-value)

     recur-value = "FREQ"=freq ";"
                [("UNTIL"
                [(";" "UNTIL" "=" enddate ";") enddate) / ("COUNT" (";" "COUNT" "=" 1*DIGIT ";")]
                ["INTERVAL" 1*DIGIT)]
                [";" "INTERVAL" "=" 1*DIGIT ";"]
                ["BYSECOND" 1*DIGIT]
                [";" "BYSECOND" "=" byseclist ";"]
                ["BYMINUTE" byseclist]
                [";" "BYMINUTE" "=" byminlist ";"]
                ["BYHOUR" byminlist]
                [";" "BYHOUR" "=" byhrlist ";"]
                ["BYDAY" byhrlist]
                [";" "BYDAY" "=" bywdaylist ";"]
                ["BYMONTHDAY" bywdaylist]
                [";" "BYMONTHDAY" "=" bymodaylist ";"]
                ["BYYEARDAY" bymodaylist]
                [";" "BYYEARDAY" "=" byyrdaylist ";"]
                ["BYWEEKNO" byyrdaylist]
                [";" "BYWEEKNO" "=" bywknolist ";"]
                ["BYMONTH" bywknolist]
                [";" "BYMONTH" "=" bymolist ";"]
                ["BYSETPOS" bymolist]
                [";" "BYSETPOS" "=" bysplist ";"]

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                ["WKST" bysplist]
                [";" "WKST" "=" weekday ";")]
                *(x-name weekday)]
                *(";" x-name "=" text) ";"
        ;Individual components MAY rule parts MUST only be specified once.
        ;Rule components parts need not be specified in particular any order.

     freq       = "SECONDLY" / "MINUTELY" / "HOURLY" / "DAILY"
                / "WEEKLY" / "MONTHLY" / "YEARLY"

     enddate    = date
     enddate    =/ date-time            ;A            ;An UTC value

     byseclist  = seconds / ( seconds *("," seconds) )

     seconds    = 1DIGIT / 2DIGIT       ;0 to 59

     byminlist  = minutes / ( minutes *("," minutes) )

     minutes    = 1DIGIT / 2DIGIT       ;0 to 59

     byhrlist   = hour / ( hour *("," hour) )

     hour       = 1DIGIT / 2DIGIT       ;0 to 23

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     bywdaylist = weekdaynum / ( weekdaynum *("," weekdaynum) )

     weekdaynum = [([plus] ordwk / minus ordwk)] weekday

     plus       = "+"

     minus      = "-"

     ordwk      = 1DIGIT / 2DIGIT       ;1 to 53

     weekday    = "SU" / "MO" / "TU" / "WE" / "TH" / "FR" / "SA"
     ;Corresponding to SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY,
     ;FRIDAY, SATURDAY and SUNDAY days of the week.

     bymodaylist = monthdaynum / ( monthdaynum *("," monthdaynum) )

     monthdaynum = ([plus] ordmoday) / (minus ordmoday)

     ordmoday   = 1DIGIT / 2DIGIT       ;1 to 31

     byyrdaylist = yeardaynum / ( yeardaynum *("," yeardaynum) )

     yeardaynum = ([plus] ordyrday) / (minus ordyrday)

     ordyrday   = 1DIGIT / 2DIGIT / 3DIGIT      ;1 to 366

     bywknolist = weeknum / ( weeknum *("," weeknum) )

     weeknum    = ([plus] ordwk) / (minus ordwk)

     bymolist   = monthnum / ( monthnum *("," monthnum) )

Dawson/Stenerson                   27            Expires September 1998

     monthnum   = 1DIGIT / 2DIGIT       ;1 to 12

     bysplist   = setposday / ( setposday *("," setposday) )

     setposday  = yeardaynum

   Description: If the property permits, multiple "recur" values MAY can be
   specified using a COMMA character (ASCII (US-ASCII decimal 44) separator
   character. The value type is a structured value consisting of a list
   of one or more recurrence grammar components. parts. Each component rule part is defined by
   a NAME=VALUE pair. The components rule parts are separated from each other by
   the SEMICOLON character (ASCII (US-ASCII decimal 59). The components rule parts are not
   ordered in any particular sequence. Individual components MAY rule parts MUST only
   be specified once.

   The FREQ component rule part identifies the type of recurrence rule. This
   component rule
   part MUST be specified in the recurrence rule. Valid values include
   SECONDLY, to specify repeating events based on an interval of a
   second or more; MINUTELY, to specify repeating events based on an
   interval of a minute or more; HOURLY, to specify repeating events
   based on an interval of an hour or more; DAILY, to specify repeating
   events based on an interval of a day or more; WEEKLY, to specify

Dawson/Stenerson                   37             Expires November 1998
   repeating events based on an interval of a week or more; MONTHLY, to
   specify repeating events based on an interval of a month or more; and
   YEARLY, to specify repeating events based on an interval of a year or
   more.

   The INTERVAL component rule part contains a positive integer representing how
   often the recurrence rule repeats. The default value is "1" or every
   second for a SECONDLY rule, or every minute for a MINUTELY rule,
   every hour for a an HOURLY rule, every day for a DAILY rule, every week
   for a WEEKLY rule, every month for a MONTHLY rule and every year for
   a YEARLY rule.

   The UNTIL component rule part defines a date-time value which bounds the
   recurrence rule in an inclusive manner. If the value specified by
   UNTIL is synchronized with the specified recurrence, this date or
   date-time becomes the last instance of the recurrence. If specified
   as a date-time value, then it MUST be specified in an UTC time
   format. If not present, and the COUNT component rule part is also not present,
   the RRULE is considered to repeat forever.

   The COUNT component rule part defines the number of occurrences at which to
   range-bound the recurrence. This component is ignored The "DTSTART" property value, if
   specified, counts as the "UNTIL"
   component is also present. first occurrence.

   The BYSECOND component rule part specifies a COMMA character (ASCII (US-ASCII decimal
   44) separated list of seconds within a minute. Valid values are 0 to
   59. The BYMINUTE component rule part specifies a COMMA character (ASCII (US-ASCII
   decimal 44) separated list of minutes within an hour. Valid values
   are 0 to 59. The BYHOUR component rule part specifies a COMMA character (ASCII (US-
   ASCII decimal 44) separated list of hours of the day. Valid values
   are 0 to 23.

   The BYDAY component rule part specifies a COMMA character (ASCII (US-ASCII decimal 44)
   separated list of days of the week; MO, indicates Monday; TU,

Dawson/Stenerson                   28            Expires September 1998
   indicates Tuesday; WE, indicates Wednesday; TH, indicates Thursday;
   FR, indicates Friday; SA, indicates Saturday; SU, indicates Sunday.

   Each BYDAY value MAY can also be preceded by a positive (+n) or negative
   (-n) integer. If present, this indicates the nth occurrence of the
   specific day within the MONTHLY or YEARLY RRULE. For example, within
   a MONTHLY rule, +1MO (or simply 1MO) represents the first Monday
   within the month, whereas -1MO represents the last Monday of the
   month. If an integer modifier is not present, it means all days of
   this type within the specified frequency. For example, within a
   MONTHLY rule, MO represents all Mondays within the month.

   The BYMONTHDAY component rule part specifies a COMMA character (ASCII decimal
   44) separated list of days of the month. Valid values are 1 to 31 or
   -31 to -1.

   Each BYMONTHDAY value MAY include a positive (+n) or negative (-n)
   integer. If present, this indicates the nth occurrence of the
   specific day of the month within the MONTHLY rule. If an integer
   modifier is not present, it means all days of this type within the
   specified frequency. For example, within a MONTHLY rule, -10 represents the tenth to the last day of
   the month.

    The BYYEARDAY component rule part specifies a COMMA character (ASCII (US-ASCII
   decimal 44) separated list of days of the year. Valid values are 1 to
   366 or -366 to -1. For example, -1 represents the last day of the

Dawson/Stenerson                   38             Expires November 1998
   year (December 31st) and -306 represents the 306th to the last day of
   the year
   (December 31st). (March 1st).

   The BYWEEKNO component rule part specifies a comma-separated COMMA character (US-ASCII decimal
   44) separated list of ordinals specifying weeks of the year. Valid
   values are 1 to 53. 53 or -53 to -1. This corresponds to weeks according
   to week numbering as defined in [ISO 8601]. That is, a week
   as "A seven day period within a calendar year, starting on a Monday
   and identified by its ordinal number within the year; the The first calendar week
   of the year is the one that includes the first Thursday 4 days of that year." This component the year. A
   week is only valid for YEARLY rules.

   Each BYWEEKNO value MAY include defined as a positive (+n) or negative (-n)
   integer. If present, this indicates seven day period, starting on the nth occurrence day of the
   specific
   week of the year within defined to be the YEARLY rule. If an integer
   modifier week start (see WKST). This rule part is not present, it means all days of this type within the
   specified frequency. only
   valid for YEARLY rules. For example, within a YEARLY rule, 3 represents the third week of
   the year.

        Note: Assuming a Monday week start, week 53 can only occur when
        Thursday is January 1 or if it is a leap year and Wednesday is
        January 1.

   The BYMONTH component rule part specifies a comma COMMA character (US-ASCII decimal
   44) separated list of months of the year. Valid values are 1 to 12.

   The WKST component rule part specifies the day on which the workweek starts.
   Valid values are MO, TU, WE, TU  WE                          ,   , TH, FR, SA and SU. This is significant
   when a WEEKLY RRULE has an interval greater than 1, and a BYDAY
   component rule
   part is specified. This is also significant when in a YEARLY RRULE
   when a BYWEEKNO rule part is specified. The default value is MO.

   The BYSETPOS component rule part specifies a COMMA character (ASCII (US-ASCII decimal
   44) separated list of values which corresponds to the nth occurrence
   within the set of events specified by the rule. Valid values are 1 to

Dawson/Stenerson                   29            Expires September 1998
   366 or -366 to -1. It MUST only be used in conjunction with another
   Byxxx component. rule part. For example "the last work day of the month" could
   be represented as:

     RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1

   Each BYSETPOS value MAY can include a positive (+n) or negative (-n)
   integer. If present, this indicates the nth occurrence of the
   specific occurrence within the set of events specified by the rule.

   If BYxxx component rule part values are found which are beyond the available
   scope (ie, BYMONTHDAY=30 in February), they are simply ignored.

   Information, not contained in the rule, necessary to determine the
   various recurrence instance start time and dates are derived from the
   Start Time (DTSTART) entry attribute. For example,
   "FREQ=YEARLY;BYMONTH=1" doesn't specify a specific day within the
   month or a time. This information would be the same as what is
   specified for DTSTART.

   BYxxx components rule parts modify the recurrence in some manner. BYxxx
   components rule
   parts for a period of time which is the same or greater than the
   frequency generally reduce or limit the number of occurrences of the
   recurrence generated. For example, "FREQ=DAILY;BYMONTH=1" reduces the
   number of recurrence instances from all days (if BYMONTH tag is not

Dawson/Stenerson                   39             Expires November 1998
   present) to all days in January. BYxxx components rule parts for a period of
   time less than the frequency generally increase or expand the number
   of occurrences of the recurrence. For example,
   "FREQ=YEARLY;BYMONTH=1,2" increases the number of days within the
   yearly recurrence set from 1 (if BYMONTH tag is not present) to 2.

   If only one BYxxx component is specified in the recurrence rule, the
   list of "n" unique values would cause "n" occurrences of the
   recurrence within each specified frequency interval, where each
   unique list value is substituted in the appropriate date position
   within DTSTART for each such occurrence. to 2.

   If multiple BYxxx components rule parts are specified, then after evaluating the
   specified FREQ and INTERVAL components, rule parts, the BYxxx components rule parts are
   applied to the current set of evaluated occurrences in the following
   order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY, BYHOUR,
   BYMINUTE, BYSECOND and BYSETPOS. BYSETPOS; then COUNT and UNTIL are evaluated.

   Here is an example of evaluating multiple BYxxx components.

     DTSTART;TZID=EST=19970105T083000 rule parts.

     DTSTART;TZID=US-Eastern:19970105T083000
     RRULE:FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9;
      BYMINUTE=30

   First, the "INTERVAL=2" would be applied to "FREQ=YEARLY" to arrive
   at "every other year". Then, "BYMONTH=1" would be applied to arrive
   at "every January, every other year". Then, "BYDAY=SU" would be
   applied to arrive at "every Sunday in January, every other year".
   Then, "BYHOUR=8,9" would be applied to arrive at "every Sunday in

Dawson/Stenerson                   30            Expires September 1998
   January at 8 AM and 9 AM, every other year". Then, "BYMINUTE=30"
   would be applied to arrive at "every Sunday in January at 8:30 AM and
   9:30 AM, every other year". Then, lacking information from RRULE, the
   second is derived from DTSTART, to end up in "every day in January at
   8:30:00 AM and 9:30:00 AM, every other year". Similarly, if the
   BYMINUTE, BYHOUR, BYDAY, BYMONTHDAY or BYMONTH component rule part were
   missing, the appropriate minute, hour, day or month would have been
   retrieved from the "DTSTART" property.

   No additional content value encoding (i.e., BACKSLASH character
   encoding) is defined for this value type.

   Example: The following is a rule which specifies 10 meetings which
   occur every other day:

     FREQ=DAILY;COUNT=10;INTERVAL=2

   There are other examples specified in the "RRULE" specification.

4.3.11  Text

   Value Name: TEXT

   Purpose This value type is used to identify values that contain human
   readable text.

   Formal Definition: The If the character set is UTF-8, the value type is
   defined by the following
   notation: notation. This must be modified depending on
   character sets. For example, the definition of TSAFE-CHAR includes
   ESC for character sets that use ISO 2022 character set switching and

Dawson/Stenerson                   40             Expires November 1998
   TSAFE-CHAR should not include NON-US-ASCII when the character set is
   US-ASCII.

     text       = text-value *("," text-value)
     ; Folded according to folded-value syntax above or
     ; encoded according to param-value syntax above.

     text-value = *(SAFE-CHAR *(TSAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR)
     ; Folded according to description above

     ESCAPED-CHAR = "\\" / "\;" / "\," / "\N" / "\n")
        ; \\ encodes \, \N or \n encodes newline
        ; \; encodes ;, \, encodes ,

     NON-ASCII  = %x80-FF
        ; use restricted by charset parameter
        ; on outer MIME object

     SAFE-CHAR

     TSAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B
                  %x5D-7E / NON-ASCII NON-US-ASCII
        ; Any character except CTLs, CTLs not needed by the current
        ; character set, DQUOTE, ";", ":", "\", ","

   Description: If the property permits, multiple "text" values MAY can be
   specified using a COMMA character (ASCII (US-ASCII decimal 44) separator
   character.

   The character set and language in which the text is represented is can be controlled by
   the "LANGUAGE" property parameters. parameter.

   An intentional formatted text line break MAY MUST only be included in a
   "TEXT" property value by representing the line break with the
   character sequence of BACKSLASH (ASCII (US-ASCII decimal 92), followed by a

Dawson/Stenerson                   31            Expires September 1998
   LATIN SMALL LETTER N (ASCII (US-ASCII decimal 110) or a LATIN CAPITAL LETTER
   N
   (ASCII (US-ASCII decimal 78), that is "\n" or "\N".

   The "TEXT" property values may also contain special characters that
   are used to signify delimiters, such as a COMMA character for lists
   of values or a SEMICOLON character for structured values. In order to
   support the inclusion of these special characters in "TEXT" property
   values, they need to be escaped with a BACKSLASH character. A
   BACKSLASH character (ASCII (US-ASCII decimal 92) in a "TEXT" property value
   MUST be escaped with another BACKSLASH character. A COMMA character
   in a "TEXT" property value MUST be escaped with a BACKSLASH character
   (ASCII
   (US-ASCII decimal 92). A SEMICOLON character in a "TEXT" property
   value MUST be escaped with a BACKSLASH character (ASCII (US-ASCII decimal
   92). However, a COLON character in a "TEXT" property value SHALL NOT
   be escaped with a BACKSLASH character.Example: A multiple line value
   of:

     Project XYZ Final Review
     Conference Room - 3B
     Come Prepared.

   would be represented as:

     Project XYZ Final Review\n Conference Room - 3B\nCome Prepared.

4.3.12  Time

   Value Name: TIME

Dawson/Stenerson                   41             Expires November 1998
   Purpose: This value type is used to identify values that contain a
   time of day.

   Formal Definition: The data type is defined by the following
   notation:

     time               = time-value *("," [WSP] time-value)

     time-value         = time-hour time-minute time-second [time-utc]

     time-hour          = 2DIGIT        ;00-23
     time-minute        = 2DIGIT        ;00-59
     time-second        = 2DIGIT        ;00-60
     ;The "60" value is used to account for years with "leap" seconds.

     time-utc   = "Z"

   Description: If the property permits, multiple "time" values MAY can be
   specified using a COMMA character (ASCII (US-ASCII decimal 44) separator
   character. No additional content value encoding (i.e., BACKSLASH
   character encoding) is defined for this value type.

   The "TIME" data type is used to identify values that contain a time
   of day. The format is based on the [ISO 8601] complete

Dawson/Stenerson                   32            Expires September 1998
   representation, basic format for a time of day. The text format
   consists of a two-digit 24-hour of the day (i.e., values 0-23), two-
   digit minute in the hour (i.e., values 0-59), and two-digit seconds
   in the minute (i.e., values 0-59). 0-60). The seconds value of 60 is only to
   be used to account for "leap" seconds. Fractions of a second are not
   supported by this format.

   In parallel to the "DATE-TIME" definition above, the "TIME" data type
   expresses time values in three forms:

   Note:

   The form of time with UTC offset MUST NOT be used. For example, the
   following is NOT VALID for a time value:

     230000-0800        ;Invalid time format

   FORM #1 LOCAL TIME

   The local time form is simply a time value that does not contain the
   UTC designator nor does it reference a time zone. For example, 11 11:00
   PM:

     230000

   Time values of this type are said to be "floating" and are not bound
   to any time zone in particular. They are used to represent the same
   hour, minute, and second value regardless of which time zone is
   currently being observed. For example, an event MAY can be defined that
   indicates that an individual will be busy from 11:00 AM to 1:00 PM
   every day, no matter which timezone time zone the person is in. In these
   cases, a local time MAY can be specified. The recipient of an iCalendar
   object with a property value consisting of a local time, without any
   relative time zone information, should interpret the value as being

Dawson/Stenerson                   42             Expires November 1998
   fixed to whatever timezone time zone the ATTENDEE is in at any given moment.
   This means that two ATTENDEEs may participate in the same event at
   different UTC times; floating time should only be used where that is
   reasonable behavior.

   In most cases, a fixed time is desired. To properly communicate a
   fixed time in a property value, either UTC time or local time with
   time zone reference MUST be specified.

   The use of local time in a TIME value without the TZID property
   parameter is to be interpreted as a local time value, regardless of
   the existence of "VTIMEZONE" calendar components in the iCalendar
   object.

   FORM #2: DATE WITH UTC TIME

   UTC time, or absolute time, is identified by a LATIN CAPITAL LETTER Z
   suffix character (ASCII (US-ASCII decimal 90), the UTC designator, appended
   to the time value. For example, the following represents 0700 07:00 AM
   UTC:

     070000Z

   The TZID property parameter MUST NOT be applied to TIME properties
   whose time values are specified in UTC.

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   FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE

   The local time with reference to time zone information form is
   identified by the use the TZID property parameter to reference the
   appropriate time zone definition. TZID is discussed in detail in the
   section on Time Zone.

   Example: The following represents 8:30 AM in New York, York in Winter, five
   hours behind UTC, in each of the three formats using the "DTSTART" "X-
   TIMEOFDAY" non-standard property:

     DTSTART:19980312T083000

     DTSTART:19980312T133000Z

     DTSTART;TZID=America-New York:19980312T083000

     X-TIMEOFDAY:083000

     X-TIMEOFDAY:133000Z

     X-TIMEOFDAY;TZID=America-New York:083000

4.3.13  URI

   Value Name: URI

   Purpose: This value type is used to identify values that contain a
   uniform resource identifier (URI) type of reference to the property
   value.

   Formal Definition: The data type is defined by the following
   notation:

Dawson/Stenerson                   43             Expires November 1998
     uri        = <As defined by any IETF RFC>

   Description: This data type might be used to reference binary
   information, for values that are large, or otherwise undesirable to
   include directly in the iCalendar object.

   The URI value formats in RFC 1738, RFC 2111 and any other IETF
   registered value format MAY can be specified.

   Any IANA registered URI format MAY can be used. These include, but are
   not limited to, those defined in RFC 1738 and RFC 2111.

   When a property parameter value is a URI value type, the URI must be
   specified as a quoted-string value.

   No additional content value encoding (i.e., BACKSLASH character
   encoding) is defined for this value type.

   Example: The following is a URI for a network file:

     http://host1.com/my-report.txt

4.3.14  UTC Offset

   Value Name: UTC-OFFSET

Dawson/Stenerson                   34            Expires September 1998

   Purpose: This value type is used to identify properties that contain
   an offset from UTC to local time.

   Formal Definition: The data type is defined by the following
   notation:

     utc-offset = time-numzone  ;As defined above in time data type

     time-numzone       = ("+" / "-") time-hour time-minute

   Description: The PLUS SIGN character MUST be specified for positive
   UTC offsets. offsets (i.e., ahead of UTC). The value of "-0000" is not
   allowed.

   No additional content value encoding (i.e., BACKSLASH character
   encoding) is defined for this value type.

   Example: The following are UTC offsets are given for standard time
   for New York (five hours behind UTC) and Geneva (one hour ahead of
   UTC):

     -0500

     +0100

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4.4 iCalendar Object

   The Calendaring and Scheduling Core Object is a collection of
   calendaring and scheduling information. Typically, this information
   will consist of a single iCalendar object. However, multiple
   iCalendar objects MAY can be sequentially grouped together. The first
   line and last line of the iCalendar object MUST contain a pair of
   iCalendar object delimiter strings. The syntax for an iCalendar
   object is as follows:

     icalobject = "BEGIN" ":" [WSP] "VCALENDAR" CRLF
                  icalbody
                  "END" ":" [WSP] "VCALENDAR" CRLF [icalobject]

   The following is a simple example of an iCalendar object:

     BEGIN:VCALENDAR
     VERSION:2.0
     PRODID:-//hacksw/handcal//NONSGML v1.0//EN
     BEGIN:VEVENT
     DTSTART:19970714T170000Z
     DTEND:19970715T045959Z
     DTEND:19970715T035959Z
     SUMMARY:Bastille Day Party
     END:VEVENT
     END:VCALENDAR

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4.5 Property

   A property is the definition of an individual attribute describing a
   calendar property or a calendar component. A property takes the form
   defined by the "contentline" notation defined in section 4.1.1.

   The following is an example of a property:

     DTSTART:19960415T133000Z

   This memo places no imposed ordering of properties within an
   iCalendar object.

   Property names, parameter names and enumerated parameter values (i.e.,
   everything to the left of the ":" on a line) are
   case insensitive. For example, the property name "DUE" is the same as
   "due" and "Due". "Due", DTSTART;TZID=Eastern:19980714T120000 is the same as
   DtStart;TzID=Eastern:19980714T120000.

4.6 Calendar Components

   The body of the iCalendar object consists of a sequence of calendar
   properties and one or more calendar components. The calendar
   properties are attributes that apply to the calendar as a whole. The
   calendar components are collections of properties that express a
   particular calendar semantic. For example, the calendar component MAY can
   specify an event, a to-do, a journal entry, time zone information, or
   free/busy time information, or an alarm.

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   The body of the iCalenar object is defined by the following notation:

     icalbody   = calprops 1*component component

     calprops   = [calscale] [method] prodid version *x-prop

     component  = 1*(eventc / todoc / journalc / freebusyc /
                / timezonec / x-name iana-comp / iana-token) x-comp)

     iana-comp  = "BEGIN" ":" iana-token CRLF

                  1*contentline

                  "END" ":" iana-token CRLF

     x-comp     = "BEGIN" ":" x-name CRLF

                  1*contentline

                  "END" ":" x-name CRLF

   An iCalendar object must include the "PRODID" and "VERSION" calendar
   properties. In addition, it must include at least one calendar
   component. Special forms of iCalendar objects are possible to publish
   just busy time (i.e., only a "VFREEBUSY" calendar component) or time
   zone (i.e., only a "VTIMEZONE" calendar component) information. In
   addition, a complex iCalendar object is possible that is used to
   capture a complete snapshot of the contents of a calendar (e.g.,
   composite of many different calendar components). More commonly, an
   iCalendar object will consist of just a single "VEVENT", "VTODO" or
   "VJOURNAL" calendar component.

4.6.1   Event Component

   Component Name: "VEVENT"

   Purpose: Provide a grouping of component properties that describe an
   event.

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   Format Definition: A "VEVENT" calendar component is defined by the
   following notation:

     eventc     = "BEGIN" ":" [WSP] "VEVENT" CRLF
                  eventprop *alarmc
                  "END" ":" [WSP] "VEVENT" CRLF

     eventprop  = *attach *attendee *categories [class] *comment
                  *contact [created] [description] [dtend / duration]
                  dtstart
                  [dtstart] *exdate *exrule [geo] [last-mod] [location]
                  [organizer] [priority] [rstatus] *rstatus *related *resources
                  *rdate *rrule dtstamp [dtstamp] [seq] [status] summary [summary]
                  [transp] uid [uid] [url] [recurid] *x-prop

Dawson/Stenerson                   46             Expires November 1998
   Description: A "VEVENT" calendar component is a grouping of component
   properties
   properties, and an OPTIONAL possibly including "VALARM" calendar component components, that represent
   represents a scheduled amount of time on a calendar. For example, it MAY
   can be an activity; such as a one-hour, one-hour long, department meeting from
   8:00 AM to 9:00 AM, tomorrow. Generally, these events an event will take up time
   on an individual calendar. Hence, the event will appear as an opaque
   interval in a search for busy time. Alternately, the event MAY can have
   its Time Transparency set to "TRANSPARENT" in order to prevent
   blocking of the event in searches for busy time.

   The "VEVENT" is also the calendar component used to specify an
   anniversary or daily reminder within a calendar. These events have a
   DATE value type for the "DTSTART" and "DTEND" properties property instead of the default
   data type of DATE-TIME. If such a "VEVENT" has an end
   time, a "DTEND" property, it
   MUST be specified as a DATE value also. The anniversary type of
   "VEVENT" MAY can span more than one date (i.e, "DTEND" property value is
   set to a calendar date after the "DTSTART" property value).

   The "DTSTART" property for a "VEVENT" specifies the inclusive start
   of the event. For recurring events, it also specifies the very first
   instance in the recurrence set. The "DTEND" property for a "VEVENT"
   calendar component specifies the non-inclusive end of the event. For
   cases where a "VEVENT" calendar component specifies a "DTSTART"
   property with a DATE data type but no "DTEND" property, the events
   non-inclusive end is the end of the calendar date specified by the
   "DTSTART" property. For cases where a "VEVENT" calendar component
   specifies a "DTSTART" property with a DATE-TIME data type but no
   "DTEND" property, the event ends on the same calendar date and time
   of day specified by the "DTSTART" property.

   The "VEVENT" calendar component MUST include the "DTSTAMP",
   "DTSTART", "SUMMARY" and "UID" properties. In addition, it MUST
   include the "SEQUENCE" property, if it's value is greater than zero.

   The "VEVENT" calendar component cannot be nested within another
   calendar component. The However, "VEVENT" calendar components MAY can be
   related to each other or to a "VTODO" or to a "VJOURNAL" calendar
   component with the "RELATED-TO" property.

Dawson/Stenerson                   37            Expires September 1998

   Example: The following is an example of the "VEVENT" calendar
   component used to represent a meeting that will also be opaque to
   searches for busy time:

     BEGIN:VEVENT
     UID:19970901T130000Z-123401@host.com
     DTSTAMP:19970901T1300Z
     DTSTART:19970903T163000Z
     DTEND:19970903T190000Z
     SUMMARY:Annual Employee Review
     CLASS:PRIVATE
     CATEGORIES:BUSINESS,HUMAN RESOURCES
     END:VEVENT

   The following is an example of the "VEVENT" calendar component used
   to represent a reminder that will not be opaque, but rather
   transparent, to searches for busy time:

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     BEGIN:VEVENT
     UID:19970901T130000Z-123402@host.com
     DTSTAMP:19970901T1300Z
     DTSTART:19970401T163000Z
     DTEND:19970402T010000Z
     SUMMARY:Laurel is in sensitivity awareness class.
     CLASS:PUBLIC
     CATEGORIES:BUSINESS,HUMAN RESOURCES
     TRANSP:TRANSPARENT
     END:VEVENT

   The following is an example of the "VEVENT" calendar component used
   to represent an anniversary that will occur annually. Since it takes
   up no time, it will not appear as opaque in a search for busy time;
   no matter what the value of the "TRANSP" property indicates:

     BEGIN:VEVENT
     UID:19970901T130000Z-123403@host.com
     DTSTAMP:19970901T1300Z
     DTSTART:19971102
     SUMMARY:Our Blissful Anniversary
     CLASS:CONFIDENTIAL
     CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION
     RRULE:FREQ=YEARLY
     END:VEVENT

4.6.2   To-do Component

   Component Name: VTODO

   Purpose: Provide a grouping of calendar properties that describe a
   to-do.

   Formal Definition: A "VTODO" calendar component is defined by the
   following notation:

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     todoc      = "BEGIN" ":" [WSP] "VTODO" CRLF
                  todoprop *alarmc
                  "END" ":" [WSP] "VTODO" CRLF

     todoprop   = *attach *attendee *categories [class] *comment
                  [completed] *contact [created] [description] dtstamp [dtstamp]
                  [dtstart] [due / duration] *exdate *exrule [geo]
                  [last-mod] [location] [organizer] [percent] priority
                  [rstatus] [priority]
                  *rstatus *related *resources *rdate *rrule
                  [recurid] [seq] [status] summary uid [summary] [uid] [url]
                  *x-prop

   Description: A "VTODO" calendar component is a grouping of component
   properties and an OPTIONAL possibly "VALARM" calendar component components that represent
   an action-item or assignment. For example, it MAY can be used to
   represent an item of work assigned to an individual; such as "turn in
   travel expense today".

   The "VTODO" calendar component MUST include the "DTSTAMP",
   "PRIORITY", "SUMMARY" and "UID" properties. In addition, it MUST
   include the "SEQUENCE" property, if it's value is greater than zero.

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   The "VTODO" calendar component cannot be nested within another
   calendar component. If However, "VTODO" calendar components need to can be
   related to each other or to a "VTODO" or to a "VJOURNAL" calendar component, they
   can specify a relationship
   component with the "RELATED-TO" property.

   A "VTODO" calendar component without the "DTSTART" and "DUE" (or
   "DURATION") properties specifies a to-do that is will be associated with
   each successive calendar dates, date, until it is completed.

   Example: The following is an example of a "VTODO" calendar component:

     BEGIN:VTODO
     UID:19970901T130000Z-123404@host.com
     DTSTAMP:19970901T1300Z
     DTSTART:19970415T133000Z
     DUE:19970416T045959Z
     SUMMARY:1996 Income Tax Preparation
     CLASS:CONFIDENTIAL
     CATEGORIES:FAMILY,FINANCE
     PRIORITY:1
     STATUS:NEEDS-ACTION
     END:VEVENT

4.6.3   Journal Component

   Component Name: VJOURNAL

   Purpose: Provide a grouping of component properties that describe a
   journal entry.

   Formal Definition: A "VJOURNAL" calendar component is defined by the
   following notation:

Dawson/Stenerson                   39            Expires September 1998

     journalc   = "BEGIN" ":" [WSP] "VJOURNAL" CRLF
                  jourprop
                  "END" ":" [WSP] "VJOURNAL" CRLF

     jourprop   = *attach *attendee *categories [class] *comment
                  *contact [created] description dtstart dtstamp [description] [dtstart] [dtstamp]
                  *exdate *exrule [last-mod] [organizer] [recurid]
                  *related *rdate *rrule [rstatus] *rstatus [seq] summary
                  uid [status]
                  [summary] [uid] [url] *x-prop

   Description: A "VJOURNAL" calendar component is a grouping of
   component properties that represent one or more descriptive text
   notes on associated with a particular calendar date. The "DTSTART"
   property is used to specify the calendar date that the journal entry
   is associated with. Generally, it will have a DATE value data type,
   but it MAY can also be used to specify a DATE-TIME value data type.
   Examples of a journal entry include a daily record of a legislative
   body or a journal entry of individual telephone contacts for the day
   or an ordered list of accomplishments for the day. The "VJOURNAL"
   calendar component can also be used to associate a document with a
   calendar date.

Dawson/Stenerson                   49             Expires November 1998
   The "VJOURNAL" calendar component does not take up time on a
   calendar. Hence, it does not play a role in free or busy time
   searches - - it is as though it has a time transparency value of
   TRANSPARENT. It is transparent to any such searches.

   The "VJOURNAL" calendar component MUST include the "DTSTAMP",
   "DTSTART", "DESCRIPTION", "SUMMARY" an "UID" properties. In addition,
   it MUST include the "SEQUENCE" property, if it's value It is greater
   than zero. transparent to any such searches.

   The "VJOURNAL" calendar component cannot be nested within another
   calendar component. If However, "VJOURNAL" calendar components need to can be
   related to each other or to a "VEVENT" or to a "VTODO" calendar
   component,
   they can specify a relationship with the "RELATED-TO" property.

   Example: The following is an example of the "VJOURNAL" calendar
   component:

     BEGIN:VJOURNAL
     UID:19970901T130000Z-123405@host.com
     DTSTAMP:19970901T1300Z
     DTSTART;VALUE=DATE:19970317
     SUMMARY:Staff meeting minutes
     DESCRIPTION:1. Staff meeting: Participants include Joe\, Lisa
       and Bob. Aurora project plans were reviewed. There is currently
       no budget reserves for this project. Lisa will escalate to
       management. Next meeting on Tuesday. Tuesday.\n
       2. Telephone Conference: ABC Corp. sales representative called
       to discuss new printer. Promised to get us a demo by Friday. Friday.\n
       3. Henry Miller (Handsoff Insurance): Car was totaled by tree.
       Is looking into a loaner car. 654-2323 (tel).
     END:VJOURNAL

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4.6.4   Free/Busy Component

   Component Name: VFREEBUSY

   Purpose: Provide a grouping of component properties that describe
   either a request for free/busy time, describe a response to a request
   for free/busy time or describe a published set of busy time.

   Formal Definition: A "VFREEBUSY" calendar component is defined by the
   following notation:

     freebusyc  = "BEGIN" ":" [WSP] "VFREEBUSY" CRLF
                  fbprop
                  "END" ":" [WSP] "VFREEBUSY" CRLF

     fbprop     = fbrequest / fbreply / busytime

     fbrequest  = 1*attendee dtstart dtend [duration] *comment dtstamp
                  [last-mod] [seq] uid
     ;This set of properties is used for free/busy time request.

     fbreply    = 1*attendee [created] *comment [dtstart dtend] dtstamp
                  1*freebusy [last-mod] [rstatus] [seq] uid
                  [url]
     ;This set of properties is used for free/busy time reply.

     busytime   = attendee dtstamp dtstart dtend *attendee *comment 1*freebusy [contact] [dtstart] [dtend]
                  [duration] [dtstamp] *freebusy [organizer] *rstatus
                  [uid] [url] *x-prop

   Description: A "VFREEBUSY" calendar component is a grouping of
   component properties that represents either a request for, a reply to
   a request for free or busy time information or a published set of
   busy time information.

   When used to request free/busy time information, the "VFREEBUSY" "ATTENDEE"
   property specifies the calendar component MUST include users whose free/busy time is being

Dawson/Stenerson                   50             Expires November 1998
   requested; the "ATTENDEE", "DTSTAMP", "DTSTART",
   "DTEND", "ORGANIZER" property specifies the calendar user who
   is requesting the free/busy time; the "DTSTART" and "UID" properties. In addition, it MUST include "DTEND"
   properties specify the
   "SEQUENCE" property, if it's value window of time that the free/busy time is greater than zero.
   being requested; the "UID" and "DTSTAMP" properties are specified to
   assist in proper sequencing of multiple free/busy time requests.

   When used to reply to a request for free/busy time, the "VFREEBUSY" "ATTENDEE"
   property specifies the calendar component MUST include user responding to the free/busy time
   request; the "ORGANIZER" property specifies the calendar user that
   originally requested the "ATTENDEE", "DTSTAMP",
   "FREEBUSY", free/busy time; the "FREEBUSY" property
   specifies the free/busy time information; and "UID" properties. In addition, it MUST include the
   "SEQUENCE" property, if it's value is greater than zero. "UID" and "DTSTAMP"
   properties are specified to assist in proper sequencing of multiple
   free/busy time replies.

   When used to publish busy time, the "VFREEBUSY" "ORGANIZER" property specifies
   the calendar component
   MUST include user associated with the published busy time; the
   "DTSTART" and "DTEND" properties specify an inclusive time window
   that surrounds the busy time information; the "FREEBUSY" property
   specifies the published busy time information; and the "ATTENDEE", "DTSTAMP", "DTSTART", "DTEND",
   "FREEBUSY" properties. "DTSTAMP"
   property specifies the date/time that iCalendar object was created.

   The "VFREEBUSY" calendar component cannot be nested within another
   calendar component. Multiple "VFREEBUSY" calendar components MAY can be
   specified within an iCalendar object. This permits the grouping of
   Free/Busy information into logical collections, such as monthly
   groups of busy time information.

Dawson/Stenerson                   41            Expires September 1998

   The "VFREEBUSY" calendar component is intended for use in iCalendar
   object methods involving requests for free time, requests for busy
   time, requests for both free and busy, and the associated replies.

   Free/Busy information can be expressed using is represented with the "FREEBBUSY" property.
   This property provides a terse representation of time periods. One or
   more "FREEBUSY" properties MAY can be specified in the "VFREEBUSY"
   calendar component to describe the Free/Busy information. component.

   When present in a "VFREEBUSY" calendar component, the "DTSTART" and
   "DTEND" properties SHOULD be specified prior to any "FREEBUSY"
   properties. In a free time request, these properties MAY can be used in
   combination with the "DURATION" property to express represent a request for a
   duration of free time within a given specified window of time.

   The recurrence properties ("RRULE", "EXRULE", "RDATE", "EXDATE") are
   not permitted within a "VFREEBUSY" calendar component. Any recurring
   events are resolved into their individual busy time periods using the
   "FREEBUSY" property.

   Example: The following is an example of a "VFREEBUSY" calendar
   component used to request free or busy time information:

     BEGIN:VFREEBUSY
     ORGANIZER:MAILTO:jane_doe@host1.com
     ATTENDEE:MAILTO:john_public@host2.com
     DTSTART:19971015T050000Z

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     DTEND:19971016T050000Z
     DTSTAMP:19970901T083000Z
     SEQUENCE:0
     UID:19970901T0830000-uid1@host1.com
     END:VFREEBUSY

   The following is an example of a "VFREEBUSY" calendar component used
   to reply to the request with busy time information:

     BEGIN:VFREEBUSY
     ORGANIZER:MAILTO:jane_doe@host1.com
     ATTENDEE:MAILTO:john_public@host2.com
     DTSTAMP:19970901T100000Z
     SEQUENCE:0
     UID:19970901T0830000-uid1@host1.com
     FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M,
      19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M
     URL:http://host2.com/pub/busy/jpublic-01.vcs
     URL:http://host2.com/pub/busy/jpublic-01.ifb
     COMMENT:This iCalendar file contains busy time information for
       the next three months.
     END:VFREEBUSY

   The following is an example of a "VFREEBUSY" calendar component used
   to published busy time information.

     BEGIN:VFREEBUSY
     ATTENDEE:jsmith@host.com
     ORGANIZER:jsmith@host.com
     DTSTART:19980313T141711Z

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     DTEND:19980410T141711Z
     FREEBUSY:19980314T233000Z/19980315T003000Z
     FREEBUSY:19980316T153000Z/19980316T163000Z
     FREEBUSY:19980318T030000Z/19980318T040000Z
     URL:http://www.host.com/calendar/busytime/jsmith.ifb
     END:VFREEBUSY

4.6.5   Timezone   Time Zone Component

   Component Name: VTIMEZONE

   Purpose: Provide a grouping of component properties that defines a
   time zone.

   Formal Definition: A "VTIMEZONE" calendar component is defined by the
   following notation:

     timezonec  = "BEGIN" ":" [WSP] "VTIMEZONE" CRLF

                  tzid [last-mod] [tzurl] 1*(standardc / daylightc)
                  *x-prop

                  "END" ":" [WSP] "VTIMEZONE" CRLF

     standardc  = "BEGIN" ":" [WSP] "STANDARD" CRLF

                  tzprop

                  "END" ":" [WSP] "STANDARD" CRLF

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     daylightc  = "BEGIN" ":" [WSP] "DAYLIGHT" CRLF

                  tzprop

                  "END" ":" [WSP] "DAYLIGHT" CRLF

     tzprop     = *comment dtstart [rdate (*rdate / rrule] *rrule)
                  *tzname tzoffsetto tzoffsetfrom *x-prop

   Description: A time zone is unambiguously defined by the set of time
   measurement rules determined by the governing body for a given
   geographic area. These rules describe at a minimum the base  offset
   from UTC for the time zone, often referred to as the Standard Time
   offset. Many locations adjust their Standard Time forward or backward
   by one hour, in order to accommodate seasonal changes in number of
   daylight hours, often referred to as Daylight  Saving Time. Some
   locations adjust their time by a fraction of an hour. Standard Time
   is also known as Winter Time. Daylight Saving Time is also known as
   Advanced Time, Summer Time, or Legal Time in certain countries. The
   following table shows the changes in time zone rules for the eastern
   United States starting from 1967. Each line represents a description
   or rule for a particular observance.

     Effective Observance Rule

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     Date       (Date/Time)             Offset  Abbreviation

     1967-*     lastSun in Oct, 02:00   -0500   EST

     1967-1973  last Sun in Apr, 02:00  -0400   EDT

     1974-1974  Jan 6,  02:00           -0400   EDT

     1975-1975  Feb 23, 02:00           -0400   EDT

     1976-1986  last Sun in Apr, 02:00  -0400   EDT

     1987-*     first Sun in Apr, 02:00 -0400   EDT

   Interoperability between two calendaring and scheduling applications,
   especially for  recurring events, to-dos or journal entries, is
   dependent on the ability to capture and  convey date and time
   information in an unambiguous format. The specification of current
   time  zone information is integral to this behavior.

   If present, the "VTIMEZONE" calendar component defines the set of
   Standard Time and Daylight Saving Time observances (or rules) for a
   particular time zone for a given interval of time. The "VTIMEZONE"
   calendar component cannot be nested within other calendar components.
   Multiple "VTIMEZONE" calendar components MAY can exist in an iCalendar
   object. In this situation, each "VTIMEZONE" MUST represent a unique
   time zone definition. This is necessary for some classes of events,
   such as airline flights, that start in one time zone and end in
   another.

Dawson/Stenerson                   53             Expires November 1998
   The "VTIMEZONE" calendar component MUST be present if the iCalendar
   object contains an RRULE that generates dates on both sides of a time
   zone shift (e.g. both in Standard Time and Daylight Saving Time)
   UNLESS
   unless the iCalendar object intends to convey a floating time (See
   the section "4.1.10.11 Time" for proper interpretation of floating
   time). It MAY can be present if the iCalendar object does not contain
   such a RRULE. In addition, if a RRULE is present, there must be valid
   time zone information for all recurrence instances.

   The "VTIMEZONE" calendar component MUST include the "TZID" property
   and at least one definition of a standard or daylight component. The
   standard or daylight component MUST include the "DTSTART",
   "TZOFFSETFROM" and "TZOFFSETTO" properties.

   An individual "VTIMEZONE" calendar component MUST be specified for
   each unique "TZID" parameter value specified in the iCalendar object.

   Each "VTIMEZONE" calendar component consists of a collection of one
   or more sub-components that describe the rule for a particular
   observance (either a Standard Time or a Daylight Saving Time
   observance). The "STANDARD" sub-component consists of a collection of
   properties that describe Standard Time. The "DAYLIGHT" sub-component
   consists of a collection of properties that describe Daylight Saving
   Time. In general this collection of properties consists of:

        - the first onset date-time for the observance

Dawson/Stenerson                   44            Expires September 1998

        - the last onset date-time for the observance, if a last onset
        is known.

        - the offset to be applied for the observance

        - a rule that describes the day and time when the observance
        takes effect

        - an optional name for the observance

   For a given time zone, there may be multiple unique definitions of
   the observances over a period of time. Each observance is described
   using either a "STANDARD" or "DAYLIGHT" sub-component. The collection
   of these sub-components is used to describe the time zone for a given
   period of time. The offset to apply at any given time is found by
   locating the observance that has the last onset date and time before
   the time in question, and using the offset value from that
   observance.

   The top-level properties in a "VTIMEZONE" calendar component are:

   The mandatory "TZID" property is a text value that uniquely
   identifies the VTIMZONE calendar component within the scope of an
   iCalendar object.

   The optional "LAST-MODIFIED" property is a UTC value that specifies
   the date and time that this time zone definition was last updated.

Dawson/Stenerson                   54             Expires November 1998
   The optional "TZURL" property is url value that points to a published
   VTIMEZONE definition.

   The collection of properties that are used to define the STANDARD and
   DAYLIGHT sub-components include:

   The mandatory "DTSTART" property gives the effective onset date and
   local time for the time zone sub-component definition. "DTSTART" in
   this usage MUST be specified as a local DATE-TIME value.

   The mandatory "TZOFFSETFROM" property gives the UTC offset which is
   in use when the onset of this time zone observance begins.
   "TZOFFSETFROM" is combined with "DTSTART" to define the effective
   onset for the time zone sub-component definition. For  example, the
   following represents the time at which the observance of Standard
   Time took effect in Fall 1967 for the eastern United States:

     DTSTART:19671029T020000

     TZOFFSETFROM:-0400

   The mandatory "TZOFFSETTO " property gives the UTC offset for the
   time zone sub-component (Standard Time or Daylight Saving Time) when
   this observance is in use.

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   The optional "TZNAME" property is the customary name for the time
   zone. It may be specified multiple times, to allow for specifying
   multiple language variants of the time zone names. This could be used
   for displaying dates.

   If specified, the onset for the observance defined by the time zone
   sub-component is defined by either the "RRULE" or "RDATE" property.
   If neither are specified, only one sub-component can be specified in
   the "VTIMEZONE" calendar component and it is assumed that the single
   observance specified is always in effect.

   The "RRULE" property defines the recurrence rule for the onset of the
   observance defined by this time zone sub-component. Some specific
   requirements for the usage of RRULE for this purpose: purpose include:

        - If observance is known to have an effective end date, the
        "UNTIL" recurrence rule parameter MUST be used to specify the
        last valid onset of this observance (i.e., the UNTIL date-time
        will be equal to the last instance generated by the recurrence
        pattern). It MUST be specified as a full DATE-TIME value, using
        local time plus the in UTC offset. time.

        - The local time and UTC offset values provided in the "DTSTART"
        property for and the given observance "TZOFFSETTO" properties MUST be used
        when generating the onset date-time values (instances) from the
        RRULE. This
        interpretation of the "DTSTART" UTC offset value is specific to
        "RRULE" usage in the  "VTIMEZONE" specification.

   Alternatively, the "RDATE" property MAY can be used to define the onset
   of the observance by giving the individual onset date and times.
   "RDATE" in this usage MUST be specified as a local DATE-TIME value
   with in
   UTC offset. time.

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   The optional "COMMENT" property is also allowed for descriptive
   explanatory text.

   Example: The following are examples of the "VTIMEZONE" calendar
   component:

   This is a simple an example showing time zone information for the Eastern
   United States using "RDATE" property. Note that this is only suitable
   for a recurring event that starts on or later than April 6, 1997 at 02:00:00 EST
   03:00:00 EDT (i.e., the earliest effective transition date and  time)
   and ends no later than April 7, 1998 02:00:00 EST (i.e., latest valid
   date and time for EST in this scenario). For example, this can be
   used for a recurring event that occurs every Friday,
   8am-9am, 8am-9:00 AM,
   starting June 1, 1997, ending December 31, 1997.

     BEGIN:VTIMEZONE
     TZID:America-New_York
     LAST-MODIFIED:19870101T000000Z
     BEGIN:STANDARD
     DTSTART:19971026T020000
     RDATE:19971026T020000

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     TZOFFSETFROM:-0400
     TZOFFSETTO:-0500
     TZNAME:EST
     END:STANDARD
     BEGIN:DAYLIGHT
     DTSTART:19971026T020000
     RDATE:19970406T020000
     TZOFFSETFROM:-0500
     TZOFFSETTO:-0400
     TZNAME:EDT
     END:DAYLIGHT
     END:VTIMEZONE

   This is a simple example showing the current time zone rules for the
   Eastern United States using a RRULE recurrence pattern. Note that
   there is no effective end date to either of the Standard Time or
   Daylight Time rules. This information would be valid for a recurring
   event starting today and continuing on into the known future.

     BEGIN:VTIMEZONE
     TZID:America-New_York
     LAST-MODIFIED:19870101T000000Z
     TZURL:http://zones.stds_r_us.net/tz/America-New_York
     BEGIN:STANDARD
     DTSTART:19671029T020000
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
     TZOFFSETFROM:-0400
     TZOFFSETTO:-0500
     TZNAME:EST
     END:STANDARD
     BEGIN:DAYLIGHT
     DTSTART:19870405T020000
     RRULE: FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4

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     TZOFFSETFROM:-0500
     TZOFFSETTO:-0400
     TZNAME:EDT
     END:DAYLIGHT
     END:VTIMEZONE

   This is an example showing a fictitious set of rules for the Eastern
   United States, where the Daylight Time rule has an effective end date
   (i.e., after that date, Daylight Time is no longer observed).

     BEGIN:VTIMEZONE
     TZID:America-New_York
     LAST-MODIFIED:19870101T000000Z
     BEGIN:STANDARD
     DTSTART:19671029T020000
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
     TZOFFSETFROM:-0400
     TZOFFSETTO:-0500
     TZNAME:EST
     END:STANDARD
     BEGIN:DAYLIGHT

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     DTSTART:19870405T020000
     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000
     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z
     TZOFFSETFROM:-0500
     TZOFFSETTO:-0400
     TZNAME:EDT
     END:DAYLIGHT
     END:VTIMEZONE

   This is an example showing a fictitious set of rules for the Eastern
   United States, where  the first Daylight Time rule has an effective
   end date. There is a second Daylight Time rule that picks up where
   the other left off.

     BEGIN:VTIMEZONE
     TZID:America-New_York
     LAST-MODIFIED:19870101T000000Z
     BEGIN:STANDARD
     DTSTART:19671029T020000
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
     TZOFFSETFROM:-0400
     TZOFFSETTO:-0500
     TZNAME:EST
     END:STANDARD
     BEGIN:DAYLIGHT
     DTSTART:19870405T020000
     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000
     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z
     TZOFFSETFROM:-0500
     TZOFFSETTO:-0400
     TZNAME:EDT
     END:DAYLIGHT
     BEGIN:DAYLIGHT
     DTSTART:19990424T020000
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=4

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     TZOFFSETFROM:-0500
     TZOFFSETTO:-0400
     TZNAME:EDT
     END:DAYLIGHT
     END:VTIMEZONE

4.6.6   Alarm Component

   Component Name: VALARM

   Purpose: Provide a grouping of component properties that define an
   alarm.

   Formal Definition: A "VALARM" calendar component is defined by the
   following notation:

     alarmc     = "BEGIN" ":" [WSP] "VALARM" CRLF
                  (audioprop / dispprop / emailprop / procprop)
                  "END" ":" [WSP] "VALARM" CRLF

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     audioprop  = alarmtype action trigger [duration repeat] attach [attach] *x-prop

     dispprop   = alarmtype action description trigger [duration
                  repeat] *x-prop

     emailprop  = alarmtype action 1*attendee *attach description
                  trigger [duration repeat] summary *x-prop

     procprop   = alarmtype action attach [description] trigger [duration
                  repeat] *x-prop

   Description: A "VALARM" calendar component is a grouping of component
   properties that is a reminder or alarm for an event or a to-do. For
   example, it may be used to define a reminder for a pending event or
   an overdue to-do.

   The "VALARM" calendar component MUST include the "ALARM-TYPE" "ACTION" and
   "TRIGGER" properties. In addition, an AUDIO type of The "ACTION" property further constrains the
   "VALARM" calendar component in the following ways:

   When the action is "AUDIO", the alarm can also include one and only
   one "ATTACH" property, which MUST point to a sound resource, which is
   rendered when the alarm is triggered.

   When the action is "DISPLAY", the alarm MUST also include the "ATTACH" property to point to a digital sound resource
   "DESCRIPTION" property, which contains the text to be played. The DISPLAY type of displayed when
   the alarm MUST include is triggered.

   When the action is "EMAIL", the "DESCRIPTION"
   property. The EMAIL type of alarm MUST include the "ATTENDEE", a "DESCRIPTION" and
   property, which contains the text to be used as the message body, a
   "SUMMARY" properties. The PROCEDURE type property, which contains the text to be used as the message
   subject, and one or more "ATTENDEE" properties, which contain the
   email address of attendees to receive the message. It can also
   include one or more "ATTACH" properties, which are intended to be

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   sent as message attachments. When the alarm is triggered, the email
   message is sent.

   When the action is "PROCEDURE", the alarm MUST include the one and only
   one "ATTACH" property to property, which MUST point to a procedure resource
   to be invoked. resource,
   which is invoked when the alarm is triggered.

   The "VALARM" calendar component MUST only appear within either a
   "VEVENT" or "VTODO" calendar component. The "VALARM" calendar components
   cannot be nested. Multiple mutually independent "VALARM" calendar
   components
   MAY can be specified. specified for a single "VEVENT" or "VTODO" calendar
   component.

   The "TRIGGER" property specifies when the alarm will be triggered.
   The "TRIGGER" property specifies a duration prior to the start of an
   event or a to-do. The "TRIGGER" edge may be explicitly set to be
   relative to the "START" or "END" of the event or to-do with the
   "RELATED" parameter of the "TRIGGER" property. The "TRIGGER" property
   value type MAY alternately can alternatively be set to an absolute calendar date and
   time of day value.

   In an alarm set to trigger on the "START" of an event or to-do, the
   "DTSTART" property MUST be present in the associated event or to-do.
   In an alarm in a "VEVENT" calendar component set to trigger on the
   "END" of the event, either the "DTEND" property MUST be present, or
   the "DTSTART" and "DURATION" properties MUST both be present. In an
   alarm in a "VTODO" calendar component set to trigger on the "END" of
   the to-do, either the "DUE" property MUST be present, or the
   "DTSTART" and "DURATION" properties MUST both be present.

   The alarm MAY can be defined such that it triggers repetitively. repeatedly. A
   definition of an alarm with a repeating trigger MUST include both the
   "DURATION" and "REPEAT" properties. The "DURATION" property specifies
   the delay period, after which the alarm will repeat. The "REPEAT"
   property specifies the number of additional repetitions that the
   alarm will triggered. This repitition count is in addition to the
   initial triggering of the alarm. Both of these properties must be
   present in order to specify a repeating alarm. If one of these two
   properties

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   are is absent, then the alarm will not repeat beyond the
   initial trigger.

   The "ALARM-TYPE" "ACTION" property is used within the "VALARM" calendar component
   to specify the type of action invoked when the alarm. alarm is triggered.
   The "ALARM-TYPE" "VALARM" properties provide enough information for a specific
   action to be invoked. It is typically the responsibility of a
   "Calendar User Agent" (CUA) to deliver the alarm in the specified
   fashion. An "ACTION" property value of AUDIO specifies an alarm that triggers with an audio sound;
   causes a value of sound to be played to alert the user; DISPLAY specifies an
   alarm that triggers with the
   "Calendar User Agent" displaying text; causes a text message to be displayed to the value of user; EMAIL
   specifies an alarm that triggers the posting of causes an electronic email message to be
   delivered to one or more email addresses; and the value of and PROCEDURE specifies an
   alarm that triggers the execution of causes a procedure. procedure to be executed. The "ALARM-TYPE" "ACTION" property
   MUST specify just one and only one of these valid values. Multiple
   categories of alarms MAY BE specified by defining more than one,
   different categories of "VALARM" calendar components within a
   "VEVENT" or "VTODO" calendar component.

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   In an AUDIO type of alarm, if the optional "ATTACH" property in the "VALARM"
   calendar component is included, it
   MUST specify an audio sound file that resource. The intention is intended
   to that the sound
   will be rendered played as the alarm effect. If an "ATTACH" property is
   specified that does not refer to a digital sound resource, then no
   audio alarm will be sounded. If or if the digital
   specified sound resource is in a cannot be rendered (because its format that is
   unsupported, or because it cannot be rendered, retrieved), then the CUA or
   other entity responsible for playing the sound may choose a fallback
   action, such as playing a built-in default sound, or playing no audio alarm will be sounded. sound
   at all.

   In a DISPLAY type of alarm, the intended alarm effect is for the text value
   of the "DESCRIPTION" property in the
   "VALARM" calendar component is intended to be displayed as to the alarm
   effect. user.

   In an EMAIL category of alarm, the intended alarm effect is
   to use the "DESCRIPTION" property in the "VALARM" calendar component
   as the body text of for an email message that is
   to be sent composed and delivered to all the addresses specified by any the
   "ATTENDEE" properties present in the "VALARM" calendar component. The "SUMMARY"
   "DESCRIPTION" property in of the "VALARM" calendar component is intended to MUST be
   used as the subject body text for of the message, and the "SUMMARY" property MUST
   be used as the
   email. subject text. Any "ATTACH" properties are in the "VALARM"
   calendar component SHOULD be sent as email attachments. attachments to the message.

   In a PROCEDURE type of alarm, the "ATTACH" property in the "VALARM" calendar
   component MUST specify a procedure or program that is intended to be
   invoked as the alarm effect. If the procedure or program is in a
   format that cannot be rendered, then no procedure alarm will be
   invoked. If the "DESCRIPTION" property is present, its value
   specifies the argument string to be passed to the procedure or
   program. "Calendar User Agents" that receive an iCalendar object with
   this category of alarm, should can disable or allow the "Calendar User" to disable
   disable, or otherwise ignore this type of alarm. While a very useful
   alarm capability, the PROCEDURE type of alarm should be treated by
   the "Calendar User Agent" as a potential security risk.

   Example: The following example is for a "VALARM" calendar component
   that specifies an audio alarm that will sound at a precise time and
   repeat 4 more times at 15 minute intervals:

     BEGIN:VALARM
     TRIGGER;VALUE=DATE-TIME:19970317T133000Z
     REPEAT:4
     DURATION:PT15M
     ALARM-TYPE: AUDIO

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     ACTION:AUDIO
     ATTACH:ftp://host.com/pub/sounds/bell-01.wav
     END:VALARM

   The following example is for a "VALARM" calendar component that
   specifies a display alarm that will trigger 15 30 minutes before the
   scheduled start of the event or the due date/time of the to-do it is
   associated with and will repeat 2 more times at 15 minute intervals:

     BEGIN:VALARM
     TRIGGER:PT30M
     REPEAT:2
     DURATION:PT15M
     ALARM-TYPE:DISPLAY

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     ACTION:DISPLAY
     DESCRIPTION:Breakfast meeting with executive\n
      team at 8:30 AM EST.
     END:VALARM

   The following example is for a "VALARM" calendar component that
   specifies an email alarm that will trigger 2 days before the
   scheduled due date/time of a to-do it is associated with. It does not
   repeat. The email has a subject, body and attachment link.

     BEGIN:VALARM
     TRIGGER:P2D
     ALARM-TYPE:EMAIL
     ACTION:EMAIL
     ATTENDEE:MAILTO:john_doe@host.com
     SUMMARY:*** REMINDER: SEND AGENDA FOR WEEKLY STAFF MEETING ***
     DESCRIPTION:A draft agenda needs to be sent out to the attendees
       to the weekly managers meeting (MGR-LIST). Attached is a
       pointer the document template for the agenda file.
     ATTACH:http://host.com/templates/agenda.doc
     END:VALARM

   The following example is for a "VALARM" calendar component that
   specifies a procedural alarm that will trigger at a precise date/time
   and will repeat 23 more times at one hour intervals. The alarm will
   invoke a procedure file.

     BEGIN:VALARM
     TRIGGER;VALUE=DATE-TIME:19980101T050000Z
     REPEAT:23
     DURATION:PT1H
     ALARM-TYPE:PROCEDURE
     ACTION:PROCEDURE
     ATTACH:ftp://host.com/novo-procs/felizano.exe
     END:VALARM

4.7 Calendar Properties

   The Calendar Properties are attributes that apply to the iCalendar
   object, as a whole. These properties do not appear within a calendar
   component. They should be specified after the "BEGIN:VCALENDAR"
   property and prior to any calendar component.

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4.7.1   Calendar Scale

   Property Name: CALSCALE

   Purpose: This property defines the calendar scale used for the
   calendar information specified in the iCalendar object.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

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   Conformance: Property MAY can be specified in an iCalendar object. The
   default value is "GREGORIAN".

   Description: This memo is based on the Gregorian calendar scale. The
   Gregorian calendar scale is assumed if this property is not specified
   in the iCalendar object. It is expected that other calendar scales
   will be defined in other specifications or by future versions of this
   memo.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     calscale   = "CALSCALE" calparam ":" [WSP] calvalue CRLF

     calparam   = *(";" xparam)

     calvalue   = "GREGORIAN" / iana-token

   Example: The following is an example of this property:

     CALSCALE:GREGORIAN

4.7.2   Method

   Property Name: METHOD

   Purpose: This property defines the iCalendar object method associated
   with the calendar object.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MAY can be specified in an iCalendar object.

   Description: When used in a MIME message entity, the value of this
   property MUST be the same as the Content-Type "method" parameter
   value. This property can only appear once within the iCalendar
   object. If either the "METHOD" property or the Content-Type "method"
   parameter is specified, then the other must also be specified.

   No methods are defined by this specification. This is the subject of
   other specifications, such as the iCalendar Transport-independent
   Interoperability Protocol (iTIP) defined by [ITIP].

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   If this property is not present in the iCalendar object, then no a
   scheduling transaction MAY MUST NOT be assumed. In such cases, the
   iCalendar object is merely being used to transport a snapshot of some
   calendar information; without the intention of conveying a scheduling
   semantic.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     method     = "METHOD" metparam ":" [WSP] method-value metvalue CRLF

     method-value

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     metparam   = *(";" xparam)

     metvalue   = iana-token

   Example: The following is a hypothetical example of this property to
   convey that the iCalendar object is a request for a meeting:

     METHOD:REQUEST

4.7.3   Product Identifier

   Property Name: PRODID

   Purpose: This property specifies the identifier for the product that
   created the iCalendar object.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MUST be specified once in an iCalendar object
   but can only appear once.
   object.

   Description: The vendor of the implementation should assure that this
   is a globally unique identifier; using some technique such as an ISO
   9070 FPI value.
   value, as defined in [ISO 9070].

   This property should not be used to alter the interpretation of an
   iCalendar object beyond the semantics specified in this memo. For
   example, it is not to be used to further the understanding of non-
   standard properties.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     prodid     = "PRODID" pidparam ":" [WSP] pidvalue CRLF

     pidparam   = *(";" xparam)

     pidvalue   = text
     ;Any text that describes the product and version
     ;and that is generally assured of being unique.

   Example: The following is an example of this property: property. It does not
   imply that English is the default language.

     PRODID:-//ABC Corporation//NONSGML My Product//EN

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4.7.4   Version

   Property Name: VERSION

   Purpose: This property specifies the identifier corresponding to the
   highest version number or the minimum and maximum range of the

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   iCalendar specification that is required in order to interpret the
   iCalendar object.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MUST be specified by in an iCalendar object,
   but MAY MUST only be specified once.

   Description: A value of "2.0" corresponds to this memo.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     version    = "VERSION" verparam ":" [WSP] vervalue CRLF

     verparam   = *(";" xparam)

     vervalue   = "2.0"         ;This memo
                / maxver
                / (minver ";" [WSP] maxver)

     minver     = <A IANA registered iCalendar version identifier>
     ;Minimum iCalendar version used needed to create parse the iCalendar object

     maxver     = <A IANA registered iCalendar version identifier>
     ;Maximum iCalendar version used needed to create parse the iCalendar object

   Example: The following is an example of this property:

     VERSION:2.0

4.8 Component Properties

   The following properties MAY can appear within calendar components, as
   specified by each component property definition.

4.8.1   Descriptive Component Properties

   The following properties specify descriptive information about
   calendar components.

4.8.1.1 Attachment

   Property Name: ATTACH

   Purpose: The property provides the capability to associate a document
   object with a calendar component.

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   Value Type: The default value type for this property is URI. The
   value type MAY can also be reset to BINARY in order to include inline
   binary encoded content information.

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   Property Parameters: Non-standard, inline encoding, value data type
   property parameters can be specified on this property.

   Conformance: The property MAY can be specified in an iCalendar object.

   Description: The property MAY only can be specified within "VEVENT", "VTODO",
   "VJOURNAL", or "VALARM" calendar components. This property
   MAY can be
   specified multiple times within an iCalendar object.

   Only the "ENCODING" and "VALUE", property parameters MAY be specified
   on this property.

   Format Definition: The property is defined by the following notation:

     attach     = ("ATTACH" "ATTACH" attparam ":" [WSP] uri  CRLF)  CRLF

     attach     =/ ("ATTACH" "ATTACH" attparam ";" [WSP] "ENCODING" "=" "b" "BASE64"
                   ";" [WSP] "VALUE" "=" "text" "BINARY" ":" [WSP] binary

     attparam   = *(";" xparam)

   Example: The following are examples of this property:

     ATTACH:CID:jsmith.part3.960817T083000.xyzMail@host1.com

     ATTACH:FTP://xyzCorp.com/pub/reports/r-960812.ps

4.8.1.2 Categories

   Property Name: CATEGORIES

   Purpose: This property defines the categories for a calendar
   component.

   Value Type: TEXT

   Property Parameters: Non-standard and language property parameters
   can be specified on this property.

   Conformance: The property MAY only can be specified within "VEVENT", "VTODO"
   or "VJOURNAL" calendar components.

   Description: This property is used to specify categories or subtypes
   of the calendar component. The categories are useful in searching for
   a calendar component of a particular type and category. Within the
   "VEVENT", "VTODO" or "VJOURNAL" calendar components, more than one
   category MAY can be specified as a list of categories separated by the
   COMMA character (ASCII (US-ASCII decimal 44).

   Only the "LANGUAGE" property parameters MAY be specified on this
   property.

   Format Definition: The property is defined by the following notation:

     categories = "CATEGORIES" [catparam] catparam ":" [WSP] catvalue text *("," text)
                  CRLF

     catparam   = ";" [WSP] languageparm [";" languageparam]
                  *(";" xparam)

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     catvalue   = "ANNIVERSARY" / "APPOINTMENT" / "BUSINESS"
                / "EDUCATION" / "HOLIDAY" / "MEETING" / "MISCELLANEOUS"
                / "NON-WORKING HOURS" / "NOT IN OFFICE" / "PERSONAL"
                / "PHONE CALL"  / "SICK DAY" / "SPECIAL OCCASION"
                / "TRAVEL" / "VACATION" / text
     ;These are just examples
     ;Used only in "VEVENT", "VTODO" and "VJOURNAL" calendar components.
   Example: The following are examples of this property:

     CATEGORIES:APPOINTMENT,EDUCATION

     CATEGORIES:MEETING

4.8.1.3 Classification

   Property Name: CLASS

   Purpose: This property defines the access classification for a
   calendar component.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MAY only can be specified once in a "VEVENT",
   "VTODO" or "VJOURNAL" calendar components. The property MAY only be
   specified once.

   Description: An access classification is only one component of the
   general security system within a calendar application. It provides a
   method of capturing the scope of the access the calendar owner
   intends for information within an individual calendar entry. The
   access classification of an individual iCalendar component is useful
   when measured along with the other security components of a calendar
   system (e.g., calendar user authentication, authorization, access
   rights, access role, etc.). Hence, the semantics of the individual
   access classifications cannot be completely defined by this memo
   alone. Additionally, due to the "blind" nature of most exchange
   processes using this memo, these access classifications cannot serve
   as an enforcement statement for a system receiving an iCalendar
   object. Rather, they provide a method for capturing the intention of
   the calendar owner for the access to the calendar component. The
   [ICMS] provides a broader description of the security system within a
   calendar application.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     class      = "CLASS" classparam ":" [WSP] classvalue CRLF

     classparam = *(";" xparam)

     classvalue = "PUBLIC" / "PRIVATE" / "CONFIDENTIAL" / iana-token
                / x-name
     ;Default is PUBLIC

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   Example: The following is an example of this property:

     CLASS:PUBLIC

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4.8.1.4 Comment

   Property Name: COMMENT

   Purpose: This property specifies non-processing information intended
   to provide a comment to the calendar user.

   Value Type: TEXT

   Property Parameters: Non-standard, alternate text representation and
   language property parameters can be specified on this property.

   Conformance: This property may can be specified in an iCalendar object.

   Description: The property MAY can be specified multiple times.

   Only the "ALTREP" or "LANGUAGE" property parameters MAY be specified
   on this property.

   Format Definition: The property is defined by the following notation:

     The property MAY be specified in any of the calendar components.

     comment    = "COMMENT" [commparam] commparam ":" [WSP] text CRLF

     commparam  = [";" [WSP] altrepparm altrepparam ] [";" [WSP] languageparm] languageparam]
                  *(";" xparam)

   Example: The following is an example of this property:

     COMMENT:The meeting really needs to include both ourselves
       and the customer. We can't hold this  meeting without them them.
       As a matter of fact\, the venue for the meeting ought to be at
       their site. - - John

   The data type for this property is TEXT.

4.8.1.5 Description

   Property Name: DESCRIPTION

   Purpose: This property provides a more complete description of the
   calendar component, than that provided by the "SUMMARY" property.

   Value Type: TEXT

   Property Parameters: Non-standard, alternate text representation and
   language property parameters can be specified on this property.

   Conformance: The property MAY can be specified in the "VEVENT", "VTODO"
   and "VTODO",
   "VJOURNAL" and "VALARM" calendar components. The property MAY can be
   specified multiple times only within a "VJOURNAL" calendar component. The
   property MAY be specified in "VALARM" calendar component.

   Description: This property is used in the "VEVENT" and "VTODO" to
   capture lengthy textual decriptions associated with the activity.

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   This property is used in the "VJOURNAL" calendar component to capture
   one more textual journal entries.

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   This property is used in the "VALARM" calendar component to capture
   the display text for a DISPLAY category of alarm, to capture the body
   text for an EMAIL category of alarm and to capture the arguement
   string for a PROCEDURE category of alarm.

   Only the "ALTREP" or "LANGUAGE" property parameters MAY be specified
   on this property.

   Format Definition: The property is defined by the following notation:

     description        = "DESCRIPTION" [descparam] descparam ":" [WSP] text CRLF

     descparam  = [";" [WSP] altrepparm] altrepparam] [";" [WSP] languageparm] languageparam]
                  *(";" xparam)

   Example: The following is an example of the property with formatted
   line breaks in the property value:

     DESCRIPTION:Meeting to provide technical review for "Phoenix"
       design.\n Happy Face Conference Room. Phoenix design team
       MUST attend this meeting.\n RSVP to team leader.

   The following is an example of the property with folding of long
   lines:

     DESCRIPTION:Last draft of the new novel is to be completed
       for the editor's proof today.

4.8.1.6 Geographic Position

   Property Name: GEO

   Purpose: This property specifies information related to the global
   position for the activity specified by a calendar component.

   Value Type: Two FLOAT. The value MUST be two SEMICOLON separated FLOAT
   values.

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY can be specified in an iCalendar object.

   Description: The property value specifies latitude and longitude, in
   that order (i.e., "LAT LON" ordering). The longitude represents the
   location east and west of the prime meridian as a positive or
   negative real number, respectively. The latitude represents the
   location north and south of the equator as a positive or negative
   real number, respectively. The longitude and latitude values MUST be
   specified as decimal degrees and should be specified to six decimal
   places. This will allow for granularity within a meter of the
   geographical position. The simple formula for converting degrees-
   minutes-seconds into decimal degrees is:

     decimal = degrees + minutes/60 + seconds/3600.

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   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

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     geo        = "GEO" geoparam ":" [WSP] geovalue CRLF

     geoparam   = *(";" xparam)

     geovalue   = float ";" [WSP] float
     ;Latitude and Longitude components

   Example: The following is an example of this property:

     GEO:37.386013;-122.082932

4.8.1.7 Location

   Property Name: LOCATION

   Purpose: The property defines the intended venue for the activity
   defined by a calendar component.

   Value Type: TEXT

   Property Parameters: Non-standard, alternate text representation and
   language property parameters can be specified on this property.

   Conformance: This property MAY can be specified in the "VEVENT" or
   "VTODO" calendar component.

   Description: Specific venues such as conference or meeting rooms may
   be explicitly specified using this property. An alternate
   representation may be specified that is a URI that points to
   directory information with more structured specification of the
   location. For example, the alternate representation may specify
   either an LDAP URI pointing to an LDAP server entry or a CID URI
   pointing to a MIME body part containing a vCard for the location.

   Only the "ALTREP" or "LANGUAGE" property parameters MAY be specified
   on this property.

   Format Definition: The property is defined by the following notation:

     location   = "LOCATION [locparam] locparam ":" [WSP] text CRLF

     locparam   = [";" [WSP] altrepparm] altrepparam] [";" [WSP] languageparm] languageparam]
                  *(";" xparam)

   Example: The following are some examples of this property:

     LOCATION:Conference Room - F123, Bldg. 002

     LOCATION;ALTREP="http://xyzcorp.com/conf-rooms/f123.vcf":
      Conference Room - F123, Bldg. 002

4.8.1.8 Percent Complete

   Property Name: PERCENT-COMPLETE

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   Purpose: This property is used by an assignee or delegatee of a to-do
   to convey the percent completion of a to-do to the Organizer.

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   Value Type: INTEGER

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY only can be specified in a "VTODO" calendar
   component.

   Description: The property value is a postive positive integer between zero
   and one hundred. A value of "0" indicates the to-do has not yet been
   started. A value of "100" indicates that the to-do has been
   completed. Integer values in between indicate the percent partially
   complete.

   When a to-do is assigned to multiple individuals, the property value
   indicates the percent complete for that portion of the to-do assigned
   to the assignee or delegatee. For example, if a to-do is assigned to
   both individuals "A" and "B". A reply from "A" with a percent
   complete of "70" indicates that "A" has completed 70% of the to-do
   assigned to them. A reply from "B" with a percent complete of "50"
   indicates "B" has completed 50% of the to-do assigned to them.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     percent = "PERCENT-COMPLETE" pctparam ":" [WSP] integer CRLF

     pctparam   = *(";" xparam)

   Example: The following is an example of this property to show 39%
   completion:

     PERCENT-COMPLETE:39

4.8.1.9 Priority

   Property Name: PRIORITY

   Purpose: The property defines the relative priority for a calendar
   component.

   Value Type: INTEGER

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MAY only can be specified in a "VEVENT" or "VTODO"
   calendar component.

   Description: The priority is specified as an integer in the range
   zero to nine. A value of zero (ASCII (US-ASCII decimal 48) specifies an
   undefined priority. A value of one (ASCII (US-ASCII decimal 49) is the
   highest priority. A value of two (ASCII (US-ASCII decimal 50) is the second
   highest priority. Subsequent numbers specify a decreasing ordinal

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   priority. A value of nine (ASCII (US-ASCII decimal 58) is the lowest
   priority.

   A CUA with a three-level priority scheme of "HIGH", "MEDIUM" and
   "LOW" is mapped into this property such that a property value in the

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   range of one (ASCII (US-ASCII decimal 49) to four (ASCII (US-ASCII decimal 52)
   specifies "HIGH" priority. A value of five (ASCII (US-ASCII decimal 53) is
   the normal or "MEDIUM" priority. A value in the range of six (ASCII (US-
   ASCII decimal 54) to nine (ASCII (US-ASCII decimal 58) is "LOW" priority.

   A CUA with a priority schema of "A1", "A2", "A3", "B1", "B2", ...,
   "C3" is mapped into this property such that a property value of one
   (ASCII
   (US-ASCII decimal 49) specifies "A1", a property value of two (ASCII (US-
   ASCII decimal 50) specifies "A2", a property value of three (ASCII (US-ASCII
   decimal 51) specifies "A3", and so forth up to a property value of 9 (ASCII
   (US-ASCII decimal 58) specifies "C3".

   Other integer values are reserved for future use.

   Within a "VEVENT" calendar component, this property specifies a
   priority for the event. This property may be useful when more than
   one event is scheduled for a given time period.

   Within a "VTODO" calendar component, this property specified a
   priority for the to-do. This property is useful in prioritizing
   multiple action items for a given time period.

   No property parameters MAY be specified on this property.

   Format Definition: The property is specified by the following
   notation:

     priority   = "PRIORITY" prioparam ":" [WSP] privalue CRLF
     ;Default is zero

     prioparam  = *(";" xparam)

     privalue   = integer       ;Must be in the range [0..9]
        ; All other values are reserved for future use

   The following is an example of a property with the highest priority:

     PRIORITY:1

   The following is an example of a property with a next highest
   priority:

     PRIORITY:2

   Example: The following is an example of a property with no priority.
   This is equivalent to not specifying the "PRIORITY" property.:

     PRIORITY:0

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4.8.1.10        Resources

   Property Name: RESOURCES

   Purpose: This property defines the equipment or resources anticipated
   for an activity specified by a calendar entity..

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   Value Type: TEXT

   Property Parameters: Non-standard, alternate text representation and
   language property parameters can be specified on this property.

   Conformance: This property MAY can be specified in a "VEVENT" or "VTODO"
   calendar component.

   Description: The property value is an arbitrary text. More than one
   resource MAY can be specified as a list of resources separated by the
   COMMA character (ASCII (US-ASCII decimal 44).

   Only the "LANGUAGE" property parameter MAY be specified on this
   property.

   Format Definition: The property is defined by the following notation:

     resources  = "RESOURCES" [resrcparam] resrcparam ":" [WSP] resvalist text *("," text) CRLF

     resrcparam = ";" [WSP] languageparm

     resvalist  = resvalue / resvalue "," [WSP] resvalist

     resvalue   = "CATERING" / "CHAIRS" / "COMPUTER PROJECTOR"
                / "EASEL" / "OVERHEAD PROJECTOR" / "SPEAKER PHONE"
                / "TABLE" / "TV" / "VCR" / "VIDEO PHONE" / "VEHICLE"
                / text
        ;These are just examples. [";" altrepparam] [";" languageparam]
                  *(";" xparam)

   Example: The following is an example of this property:

     RESOURCES:EASEL,PROJECTOR,VCR

     RESOURCES;LANGUAGE=fr:1 raton-laveur

4.8.1.11        Status

   Property Name: STATUS

   Purpose: This property defines the overall status or confirmation for
   the calendar component.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY only can be specified in the "VEVENT",
   "VTODO", "VTODO"
   and "VJOURNAL" calendar components.

   Description: In a group scheduled calendar component, the property is
   used by the "Organizer" to provide a confirmation of the event to the
   "Attendees". For example in a "VEVENT" calendar component, the
   "Organizer" can indicate that a meeting is tentative, confirmed or
   cancelled. In a "VTODO" calendar component, the "Organizer" can
   indicate that an action item needs action, is completed, is in
   process or being worked on, or has been cancelled. In a "VJOURNAL"

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   calendar component, the "Organizer" can indicate that a journal entry
   is draft, final or has been cancelled or removed.

   No property parameter MAY be specified on this property.

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   Format Definition: The property is defined by the following notation:

     status     = "STATUS" statparam] ":" [WSP] statvalue CRLF

     statparam  = *(";" xparam)

     statvalue  = "TENTATIVE"           ;Indicates event is
                                        ;tentative.
                / "CONFIRMED"           ;Indicates event is
                                        ;definite.
                / "CANCELLED"           ;Indicates event was
                                        ;cancelled.
        ;Status values for a "VEVENT"

     statvalue  =/ "NEEDS-ACTION"       ;Indicates to-do needs action.
                / "COMPLETED"           ;Indicates to-do completed.
                / "IN-PROCESS"          ;Indicates to-do in process of
                / "CANCELLED"           ;Indicates to-do was cancelled.
        ;Status values for "VTODO".

     statvalue  =/ "DRAFT"              ;Indicates journal is draft.
                / "FINAL"               ;Indicates journal is final.
                / "CANCELLED"           ;Indicates journal is removed.
        ;Status values for "VJOURNAL".

   Example: The following is an example of this property for a "VEVENT"
   calendar component:

     STATUS:TENTATIVE

   The following is an example of this property for a "VTODO" calendar
   component:

     STATUS:NEEDS-ACTION

   The following is an example of this property for a "VJOURNAL"
   calendar component:

     STATUS:DRAFT

4.8.1.12        Summary

   Property Name: SUMMARY

   Purpose: This property defines a short summary or subject for the
   calendar component.

   Value Type: TEXT

   Property Parameters: Non-standard, alternate text representation and
   language property parameters can be specified on this property.

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   Conformance: The property MUST can be specified in the "VEVENT", "VTODO"
   and "VTODO",
   "VJOURNAL" calendar components. In addition, it MAY appear in the and "VALARM" calendar component. components.

   Description: This property is used in the "VEVENT", "VTODO" and
   "VJOURNAL" calendar components to capture a short, one line summary
   about the activity or journal entry.

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   This property is used in the "VALARM" calendar component to capture
   the subject of an EMAIL category of alarm.

   Only the "ALTREP" and "LANGUAGE" property parameters MAY be specified
   on this property.

   Format Definition: The property is defined by the following notation:

     summary    = "SUMMARY" [summparam] summparam ":" [WSP] text CRLF

     summparam  = [";" [WSP] altrepparm] altrepparam] [";" [WSP] languageparm] languageparam]
                  *(";" xparam)

   Example: The following is an example of this property:

     SUMMARY:Department Party

4.8.2   Date and Time Component Properties

   The following properties specify date and time related information in
   calendar components.

4.8.2.1 Date/Time Completed

   Property Name: COMPLETED

   Purpose: This property defines the date and time that a to-do was
   actually completed.

   Value Type: DATE-TIME

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MAY only can be specified in a "VTODO"
   component in an iCalendar object. calendar
   component.

   Description: The date and time must be in a UTC format.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     completed  = "COMPLETED" compparam ":" [WSP] date-time CRLF

     compparam  = *(";" xparam)

   Example: The following is an example of this property:

     COMPLETED:19960401T235959Z

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4.8.2.2 Date/Time End

   Property Name: DTEND

   Purpose: This property specifies the date and time that a calendar
   component ends.

   Value Type: The default value type is DATE-TIME. The value type MAY
   BE can
   be reset to a DATE value type.

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   Property Parameters: Non-standard, value data type, time zone
   identifier property parameters can be specified on this property.

   Conformance: This property MAY only can be specified within the "VEVENT",
   "VFREEBUSY", "VEVENT" and "VTIMEZONE"
   "VFREEBUSY" calendar components.

   Description: Within the "VEVENT" calendar component, this property
   defines the date and time by which the event ends. The value MUST be
   later in time than the value of the "DTSTART" property.

   Within the "VFREEBUSY" calendar component, this property defines the
   end date and time for the free or busy time information. The time
   MUST be specified as in the UTC time format. The value MUST be later
   in time than the value of the "DTSTART" property.

   Only the "VALUE" and "TZID" property parameters MAY be specified on
   this property. The "TZID" property parameter MAY only be specified
   when the value type is DATE-TIME.

   Format Definition: The property is defined by the following notation:

     dtend      = "DTEND" [dtendparam]":" [WSP] dtendparam":" dtendval CRLF

     dtendparam = [";" [WSP] "VALUE" "=" "DATE-TIME"] ("DATE-TIME" / "DATE")]
                  [";" [WSP] "TZID" "=" paramtext

     dtendparam =/ ";" [WSP] "VALUE" "=" "DATE" tzidparam]
                  *(";" xparam)

     dtendval   = date-time / date
     ;Value MUST match value type

   Example: The following is an example of this property:

     DTEND:19960401T235959Z

     DTEND;VALUE=DATE:19980704

4.8.2.3 Date/Time Due

   Property Name: DUE

   Purpose: This property defines the date and time that a to-do is
   expected to be completed.

   Value Type: The default value type is DATE-TIME. The value type MAY
   BE can
   be reset to a DATE value type.

   Property Parameters: Non-standard, value data type, time zone
   identifier property parameters can be specified on this property.

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   Conformance: The property MAY only can be specified in once within a "VTODO"
   calendar
   component and only once. component.

   Description: The value MUST be a date/time equal to or after the
   DTSTART value, if specified.

   Only the "VALUE" and "TZID" property parameters MAY be specified on
   this property. The "TZID" property parameter MAY only be specified
   when the value type is DATE-TIME.

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   Format Definition: The property is defined by the following notation:

     due        = "DUE" [dueparam]":" [WSP] dueparam":" dueval CRLF

     dueparam   = [";" [WSP] "VALUE" "=" "DATE-TIME"] ("DATE-TIME" / "DATE")]
                  [";" [WSP] "TZID" "=" paramtext

     dueparam   =/ ";" [WSP] "VALUE" "=" "DATE" tzidparam]
                  *(";" xparam)

     dueval     = date-time / date
     ;Value MUST match value type

   Example: The following is an example of this property:

     DUE:19960401T235959Z

     DUE:19980430T235959Z

4.8.2.4 Date/Time Start

   Property Name: DTSTART

   Purpose: This property specifies when the calendar component begins.

   Value Type: The default value type is DATE-TIME. The DATE-TYPE time value
   will MUST
   be one of the forms defined for the DATE-TIME value type. The value
   type MAY BE can be reset to a DATE value type.

   Property Parameters: Non-standard, value data type, time zone
   identifier property parameters can be specified on this property.

   Conformance: This property MAY can be specified within the "VEVENT",
   "VTODO", "VFREEBUSY", and "VTIMEZONE" calendar components.

   Description: Within the "VEVENT" calendar component, this property
   defines the start date and time for the event. The property is
   REQUIRED in "VEVENT" calendar components. Events MAY can have a start
   date/time but no end date/time. In that case, the event does not take
   up any time.

   Within the "VFREEBUSY" calendar component, this property defines the
   start date and time for the free or busy time information. The time
   MUST be specified in UTC time.

   Within the "VTIMEZONE" calendar component, this property defines the
   effective start date and time for a time zone specification. This
   property is REQUIRED within each STANDARD and DAYLIGHT part included
   in "VTIMEZONE" calendar components. The time components and MUST be specified in the UTC time format.

   Only as a local
   DATE-TIME without the "VALUE" and "TZID" property parameters MAY be specified on
   this property. The "TZID" property parameter MAY only be specified
   when the value type is DATE-TIME. parameter.

   Format Definition: The property is defined by the following notation:

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     dtstart    = "DTSTART" [dtstparam] dtstparam ":" [WSP] dtstval CRLF

     dtstparam  = [";" [WSP] "VALUE" "=" "DATE-TIME"] ("DATE-TIME" / "DATE")]
                  [";" [WSP] "TZID" "=" paramtext]

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     dtstparam  =/ ";" [WSP] "VALUE" "=" "DATE" tzidparam]
                  *(";" xparam)

     dtstval    = date-time / date
     ;Value MUST match value type

   Example: The following is an example of this property:

     DTSTART:19980118T073000Z

4.8.2.5 Duration

   Property Name: DURATION

   Purpose: The property specifies a positive duration of time .

   Value Type: DURATION

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MAY can be specified in a "VEVENT", "VTODO",
   "VFREEBUSY" or and "VALARM" calendar components.

   Description: In a "VEVENT" calendar component the property may be
   used to specify a duration of the event, instead of an explicit end
   date/time. In a "VTODO" calendar component the property may be used
   to specify a duration for the to-do, instead of an explicit due
   date/time. In a "VFREEBUSY" calendar component the property may be
   used to specify the interval of free time being requested. In a
   "VALARM" calendar component the property may be used to specify the
   delay period prior to repeating an alarm.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     duration   = "DURATION" durparam ":" [WSP] duration CRLF
                  ;consisting of a positive duration of time.

     durparam   = *(";" xparam)

   Example: The following is an example of this property that specifies
   an interval of time of 1 hour and zero minutes and zero seconds:

     DURATION:PT1H0M0S

   The following is an example of this property that specifies an
   interval of time of 15 minutes.

     DURATION:PT15M

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4.8.2.6 Free/Busy Time

   Property Name: FREEBUSY

   Purpose: The property defines one or more free or busy time
   intervals.

   Value Type: PERIOD. The data date and time value values MUST be in a an UTC time
   format.

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   Property Parameters: Non-standard or free/busy time type property
   parameters can be specified on this property.

   Conformance: The property MAY only can be specified in a "VFREEBUSY" calendar
   component.

   Property Parameter: "FBTYPE" and non-standard parameters can be
   specified on this property.

   Description: These time periods MAY can be specified as either a start
   and end date-time or a start date-time and duration. The date and
   time MUST be a UTC time format.

   The "FREEBUSY" property MAY include the "TYPE" property parameter to
   specify whether the information defines a FREE or BUSY time interval.
   The default "TYPE" property parameter value is BUSY.

   If the "TYPE" property parameter is set to "BUSY", then the property
   MAY also include the "BSTAT" property parameter to provide added
   information about the busy time. For example, if the busy time is
   associated with a time interval that would be unavailable for
   scheduling in any case the parameter MAY BE set to UNAVAILABLE or if
   the busy time that has been tentatively scheduled the parameter MAY
   BE set to TENTATIVE. The default "BSTAT" property parameter value is
   BUSY, providing no additional busy status information.

   "FREEBUSY" properties within the "VFREEBUSY" calendar component
   should be sorted in ascending order, based on start time and then end
   time, with the earliest periods first.

   The "FREEBUSY" property MAY can specify more than one value, separated by
   the COMMA character (ASCII (US-ASCII decimal 44). In such cases, the
   "FREEBUSY" property values should all be of the same "TYPE" and "BSTAT" "FBTYPE"
   property parameter type (e.g., all values of a particular "TYPE" and "BSTAT" "FBTYPE"
   listed together in a single property).

   No property parameters other than the property specific "TYPE" and
   "BSTAT" parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     freebusy   = "FREEBUSY" [";" [WSP] fbparmlist] fbparam ":" [WSP] fbvalue
                  CRLF

     fbparmlist = fb-free / fb-busy

     fb-free    = "TYPE" "=" "FREE"

     fb-busy

     fbparam    = ["TYPE" "=" "BUSY"] [";" [WSP] fbstatus]
     ;Default is BUSY

     fbstatus   = "BSTAT" "="
                  "BUSY"        ;Represents busy time interval.
                / "UNAVAILABLE" ;Represents busy, but unavailable
                                ;interval for cheduling; such as
                                ;out-of-office or non-working hours.
                / "TENTATIVE"   ;Represents busy, but only tentatively
                                ;scheduled interval.
                / iana-token    ;Represents other registered busy status

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                / x-name        ;Represents experimental busy status
     ;Default is BUSY fbtypeparam] *(";" xparam)

     fbvalue    = period *["," [WSP] period]
     ;Time value MUST be in the UTC time format.

   Example: The following are some examples of this property:

     FREEBUSY;BSTAT=UNAVAILABLE:19970308T160000Z/PT8H30M

     FREEBUSY;TYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H

     FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:19970308T160000Z/PT8H30M

     FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H

     FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H,
      19970308T230000Z/19970309T000000Z

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4.8.2.7 Time Transparency

   Property Name: TRANSP

   Purpose: This property defines whether an event is transparent or not
   to busy time searches.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY only can be specified in once within a "VEVENT"
   calendar component.

   Description: Transparency is the state that determines whether an
   event takes up time on a calendar, and with be reflected as "busy
   time", or is just "penciled in" to the calendar, and will not be
   reflected as "busy time". If the event is transparent, then other
   events can be scheduled in the same time period without there being a
   time period conflict. If not specified, the default state is OPAQUE.

   No property parameters MAY be specified on this property.

   Format Definition: The property is specified by the following
   notation:

     transp     = "TRANSP" tranparam ":" [WSP] transvalue CRLF

     tranparam  = *(";" xparam)

     transvalue = "OPAQUE"      ;Blocks or opaque on busy time searches.
                / "TRANSPARENT" ;Transparent on busy time searches.
        ;Default value is OPAQUE

   Example: The following is an example of this property for an event
   that is transparent or does not block on free/busy time searches:

     TRANSP:TRANSPARENT

   The following is an example of this property for an event that is
   opaque or blocks on free/busy time searches:

     TRANSP:OPAQUE

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4.8.3   Time Zone Component Properties

   The following properties specify time zone information in calendar
   components.

4.8.3.1 Time Zone Identifier

   Property Name: TZID

   Purpose: This property specifies the text value that uniquely
   identifies the VTIMZONE "VTIMEZONE" calendar component.

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   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MUST be specified in a "VTIMEZONE"
   calendar component.

   Description: This is the key label by which a time zone object calendar
   component is referenced by any iCalendar properties whose data type
   is either DATE-TIME or TIME. TIME and not intended to specify a UTC or
   a"floating" time. The presence of the SOLIDUS character (ASCII (US-ASCII
   decimal 47) as a prefix, indicates that this TZID represents an
   unique ID in a globally defined time zone registry (when such
   registry is defined).

   No property parameters MAY be specified on this property.

   Format Definition: This property is defined by the following
   notation:

     tzid       = "TZID" tzidpropparam ":" [WSP] [tzidprefix] text CRLF

     tzidprefix

     tzidpropparam      = *(";" xparam)

     ;tzidprefix        = "/"
     ; Defined previously. Just listed here for reader convenience.

   Example: The following are examples of non-globally unique time zone
   identifiers:

     TZID:America-New_York

     TZID:/US-California-Los_Angeles

     TZID:California-Los_Angeles

   The following is an example of a globally unique time zone
   identifier:

     TZID:/US-New York-New_York

     TZID:/US-New_York-New_York

4.8.3.2 Time Zone Name

   Property Name: TZNAME

   Purpose: This property specifies the customary designation for a time
   zone description.

   Value Type: TEXT

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   Property Parameters: Non-standard and language property parameters
   can be specified on this property.

   Conformance: This property MAY only can be specified in the "VTIMEZONE"
   calendar component.

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   Description: This property may be specified in multiple languages; in
   order to provide for different national language requirements.

   Only the "LANGUAGE" property parameter MAY be specified on this
   property.

   Format Definition: This property is defined by the following
   notation:

     tzname     = "TZNAME" [tznparam] tznparam ":" [WSP] text CRLF

     tznparam   = ";" [WSP] languageparm [";" languageparm]
                  *(";" xparam)

   Example: The following are examples example of this property:

     TZNAME: EST

     TZNAME;LANGUAGE=fr-CA:HNE

4.8.3.3 Time Zone Offset From

   Property Name: TZOFFSETFROM

   Purpose: This property specifies the offset which is in use prior to
   this time zone observance.

   Value Type: UTC-OFFSET

   Conformance: This property MUST only be specified in a "VTIMEZONE"
   calendar component. A "VTIMEZONE" calendar component MUST include
   this property.

   Description: This property specifies the offset which is in use prior
   to this time observance. It is used to calculate the absolute time at
   which the transition to a given observance takes place. This property
   MUST only be specified in a "VTIMEZONE" calendar component. A
   "VTIMEZONE" calendar component MUST include this property. The
   property value is a signed numeric indicating the number of hours and
   possibly minutes from UTC. Positive numbers represents time zones
   east, or ahead of UTC. Negative numbers represents time zones west
   of, or behind UTC.

   No property parameter MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     tzoffsetfrom       = "TZOFFSETFROM" ":" [WSP] utc-offset CRLF

   Example:

     TZNAME:EST

   The following are examples is an example of this property:

     TZOFFSETFROM:-0500

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     TZOFFSETFROM:+0530

4.8.3.4 property when two different
   languages for the time zone name are specified:

     TZNAME;LANGUAGE=en:EST
     TZNAME;LANGUAGE=fr-CA:HNE

4.8.3.3 Time Zone Offset To From

   Property Name: TZOFFSETTO TZOFFSETFROM

   Purpose: This property specifies the offset which is in use in prior to
   this time zone observance.

   Value Type: UTC-OFFSET

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY only MUST be specified in a "VTIMEZONE"
   calendar component. A "VTIMEZONE" calendar component MUST include
   this property.

   Description: This property specifies the offset which is in use in prior
   to this time zone observance. It is used to calculate the absolute time
   for at
   which the new observance. transition to a given observance takes place. This property
   MUST only be specified in a "VTIMEZONE" calendar component. A
   "VTIMEZONE" calendar component MUST include this property. The
   property value is a signed numeric indicating the number of hours and
   possibly minutes from UTC. Positive numbers represents time zones east,
   east of the prime meridian, or ahead of UTC. Negative numbers
   represents time zones west of, or behind UTC.

   No property parameter MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     tzoffsetto = "TZOFFSETTO" ":" [WSP] utc-offset CRLF

   Example: The following are examples of this property:

     TZOFFSETTO:-0500

     TZOFFSETTO:+0530

4.8.3.5 Time Zone URL

   Property Name: TZURL

   Purpose: The TZURL provides a means for a VTIMEZONE component to
   point to a network location that can be used to retrieve an up-to-
   date version of itself.

   Value Type: URI

   Conformance: This property MAY only be specified in a "VTIMEZONE"
   calendar component.

   Description: The TZURL provides a means for a VTIMEZONE component to
   point to a network location that can be used to retrieve an up-to-
   date version of itself.  This provides a hook to handle changes
   government bodies impose upon timezone definitions.  Retrieval of
   this resource results in an iCalendar object containing a single
   VTIMEZONE component and a METHOD property set to PUBLISH.

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   No property parameter MAY be specified on this property. the prime meridian, or behind UTC.

   Format Definition: The property is defined by the following notation:

     tzurl

     tzoffsetfrom       = "TZURL" "TZOFFSETFROM" frmparam ":" [WSP] uri utc-offset
                          CRLF

     frmparam   = *(";" xparam)

   Example: The following is an example are examples of this property:

     TZURL:http://timezones.r.us.net/tz/US-California-Los_Angeles

4.8.4   Relationship Component Properties

   The following properties specify relationship information in calendar
   components.

4.8.4.1 Attendee

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     TZOFFSETFROM:-0500

     TZOFFSETFROM:+1345

4.8.3.4 Time Zone Offset To

   Property Name: ATTENDEE TZOFFSETTO

   Purpose: The This property defines an attendee within a calendar
   component. specifies the offset which is in use in this
   time zone observance.

   Value Type: CAL-ADDRESS

   Conformance: This UTC-OFFSET

   Property Parameters: Non-standard property MUST parameters can be
   specified in an iCalendar object
   that specifies a group scheduled calendar entity. on this property.

   Conformance: This property MUST be specified in an iCalendar object that specifies the publication of a "VTIMEZONE"
   calendar user's busy time. component.

   Description: This property specifies the offset which is not specified in an
   iCalendar object that specifies only a use in
   this time zone definition or that
   defines calendar entities that are not group scheduled entities, but
   are entities only on a single user's calendar.

   Description: The property is specified within the "VEVENT", "VTODO",
   "VJOURNAL calendar components to specify participants, non-
   participants and the chair of a group scheduled calendar entity. The
   property is specified within the "VFREEBUSY" calendar component to
   specify the calendar user associated with the free or busy time. The
   property is specified within an "EMAIL" category of the "VALARM"
   calendar component to specify an email address that observance. It is used to receive the
   email type of iCalendar alarm.

   The property has the property parameter CN, for the common or
   displayable name associated with the calendar address, ROLE, for the
   intended role that the attendee will have in the calendar component;
   ATTSTAT, for the status of the attendee's participation; RSVP, calculate the absolute time
   for the new observance. The property value is a signed numeric
   indicating whether the favor number of hours and possibly minutes from UTC.
   Positive numbers represents time zones east of a reply is requested; EXPECT, to
   indicate the expectation prime meridian, or
   ahead of UTC. Negative numbers represents time zones west of the attendee's participation
   prime meridian, or behind UTC.

   Format Definition: The property is defined by the
   originator; MEMBER, following notation:

     tzoffsetto = "TZOFFSETTO" toparam ":" utc-offset CRLF

     toparam    = *(";" xparam)

   Example: The following are examples of this property:

     TZOFFSETTO:-0400

     TZOFFSETTO:+1245

4.8.3.5 Time Zone URL

   Property Name: TZURL

   Purpose: The TZURL provides a means for a VTIMEZONE component to indicate the groups that the attendee belongs
   to; DELEGATED-TO,
   point to indicate the calendar users a network location that the original
   request was delegated to; and DELEGATED-FROM, to indicate whom the
   request was delegated from; SENT-BY, can be used to indicate whom is acting on
   behalf retrieve an up-to-
   date version of the ATTENDEE and DIR, to indicate the itself.

   Value Type: URI that points to
   the directory information corresponding to the attendee. These

   Property Parameters: Non-standard property parameters MAY only can be
   specified on an "ATTENDEE" this property.

   Conformance: This property

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   in either a "VEVENT", "VTODO" or "VJOURNAL" calendar component. They
   MUST not can be specified in an "ATTENDEE" property in a "VFREEBUSY" or
   "VALARM" "VTIMEZONE" calendar
   component.

   A recipient delegated

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   Description: The TZURL provides a request MUST inherit the RSVP and EXPECT
   values from the attendee that delegated the request to them.

   Multiple attendees MAY be specified by including multiple "ATTENDEE"
   properties within the MIME calendaring entity.

   Only the "TYPE", "CN", "ROLE", "ATTSTAT", "RSVP", "DELEGATED-TO",
   "DELEGATED-FROM", "SENT-BY" or "DIR" property specific parameters MAY means for a VTIMEZONE component to
   point to a network location that can be specified on used to retrieve an up-to-
   date version of itself.  This provides a hook to handle changes
   government bodies impose upon time zone definitions.  Retrieval of
   this property. In addition, the "LANGUAGE" resource results in an iCalendar object containing a single
   VTIMEZONE component and a METHOD property
   parameter MAY be specified on this property. set to PUBLISH.

   Format Definition: The property is defined by the following notation:

     attendee

     tzurl      = "ATTENDEE" *(";" [WSP] attparam) "TZURL" tzurlparam ":" [WSP]
                  cal-address uri CRLF

     attparam   = typeparm / cnparm / roleparm / statusparm / rsvpparm
                / memberparm / deletoparm / delefromparm
                / sentbyparm / dirparm

     typeparm

     tzurlparam = "TYPE" "="
                ("INDIVIDUAL"   ; An individual
                / "GROUP"       ; A group of individuals
                / "RESOURCE"    ; A physical resource
                / "ROOM"        ; A room resource
                / "UNKNOWN")    ; Otherwise not known
     ;Default value *(";" xparam)

   Example: The following is INDIVIDUAL

     cnparm     = "CN" "=" param-value

     roleparm   = "ROLE" "="
                 ("CHAIR"       ; Indicates CHAIR an example of the this property:

     TZURL:http://timezones.r.us.net/tz/US-California-Los_Angeles

4.8.4   Relationship Component Properties

   The following properties specify relationship information in calendar entity
                / "REQ-PARTICIPANT" ; Indicates a participant whose
        ;participation is required
                / "OPT-PARTICIPANT" ;Indicates a participant whose
        ;participation is optional
                / "NON-PARTICIPANT" ;Indicates
   components.

4.8.4.1 Attendee

   Property Name: ATTENDEE

   Purpose: The property defines an "Attendee" within a participant who
        ;is copied for information purposes only
     ;Default is REQ-PARTICIPANT

     statusparm = "ATTSTAT" "="
                ("NEEDS-ACTION" ; Indicates event or to-do needs action
                / "ACCEPTED"    ; Indicates event or to-do accepted
                / "DECLINED"    ; Indicates event calendar
   component.

   Value Type: CAL-ADDRESS

   Property Parameters: Non-standard, language, calendar user type,
   group or to-do not accepted
                / "TENTATIVE"   ; Indicates event list membership, participation role, participation status,
   RSVP expectation, delegatee, delegator, sent by, common name or to-do tentatively
                ; accepted. Status MAY change
   directory entry reference property parameters can be specified on
   this property.

   Conformance: This property MUST be specified in the future.
                / "COMPLETED"   ; Indicates to-do was completed.
                ; COMPLETED an iCalendar object
   that specifies a group scheduled calendar entity. This property has date/time completed.
                / "IN-PROCESS"  ;Indicates to-do is MUST
   NOT be specified in an iCalendar object when publishing the calendar
   information (e.g., NOT in an iCalendar object that specifies the process
   publication of
                ; being completed.

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                / "DELEGATED"   ; Indicates event or a calendar user's busy time, event, to-do delegated
                ; to another ATTENDEE
     ;Default is NEEDS-ACTION

     rsvpparm   = "RSVP" "="
                  ("TRUE"               ; Indicates response requested
                / "FALSE")              ; Indicates no response needed
     ;Default or journal).
   This property is FALSE

     memberparm = "MEMBER" "=" DQUOTE uri DQUOTE
                  *("," [WSP] DQUOTE uri DQUOTE)
     ; Indicates not specified in an iCalendar object that specifies
   only a group time zone definition or mailing list
     ; that defines calendar entities that
   are not group scheduled entities, but are entities only on a single
   user's calendar.

   Description: The property is MUST only be specified within calendar
   components to specify participants, non-participants and the chair of
   a MAILTO URI as defined in [RFC 1738]
     ; group scheduled calendar entity. The property is specified within
   an "EMAIL" category of the "VALARM" calendar component to specify an
   email address that is to receive the email type of iCalendar alarm.

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   The property parameter value must be put CN, is for the common or displayable name
   associated with the calendar address; ROLE, for the intended role
   that the attendee will have in the calendar component; PARTSTAT, for
   the status of the attendee's participation; RSVP, for indicating
   whether the favor of a quoted string.

     deletoparm = "DELEGATED-TO" "=" DQUOTE uri DQUOTE
                  *("," [WSP] DQUOTE uri DQUOTE)
     ; Indicates who reply is requested; CUTYPE, to indicate the
   type of calendar user; MEMBER, to indicate the groups that the
   attendee belongs to; DELEGATED-TO, to indicate the calendar users
   that the original request is was delegated to; and DELEGATED-FROM, to
     ; MUST be a MAILTO URI as defined in [RFC 1738]
     ; The parameter value must be put in a quoted string.delefromparm =
     "DELEGATED-FROM" "=" DQUOTE uri DQUOTE
                    *("," [WSP]DQUOTE uri DQUOTE)
     ;Indicates who
   indicate whom the request is was delegated from
     ; MUST be a MAILTO URI as defined in [RFC 1738]
     ; The parameter value must be put in a quoted string.

     sentbyparm = "SENT-BY" "=" DQUOTE uri DQUOTE
     ; Indicates a calendar user from; SENT-BY, to indicate
   whom is acting on behalf of the ATTENDEE; and DIR, to indicate the
   URI that points to the directory information corresponding to the
   attendee.
     ; MUST These property parameters can be a MAILTO URI as defined specified on an "ATTENDEE"
   property in [RFC 1738]
     ; The parameter value must either a "VEVENT", "VTODO" or "VJOURNAL" calendar
   component. They MUST not be put specified in an "ATTENDEE" property in a quoted string.dirparm
   "VFREEBUSY" or "VALARM" calendar component. If the LANGUAGE property
   parameter is specified, the identified language applies to the CN
   parameter.

   A recipient delegated a request MUST inherit the RSVP and ROLE values
   from the attendee that delegated the request to them.

   Multiple attendees can be specified by including multiple "ATTENDEE"
   properties within the calendar component.

   Format Definition: The property is defined by the following notation:

     attendee   = "DIR" "=" DQUOTE uri DQUOTE "ATTENDEE" attparam ":" cal-address CRLF

     attparam   = [";" cutypeparam] [";"memberparam] [";" roleparam]
                  [";" partstatparam] [";" rsvpparam] [";" deltoparam]
                  [";" delfromparam] [";" sentbyparam] [";"cnparam]
                  [";" dirparam] [";" languageparam] *(";" xparam)

   Example: The following are examples of this property's use for a to-
   do:

     ORGANIZER:MAILTO:jsmith@host1.com
     ATTENDEE;MEMBER="MAILTO:DEV-GROUP@host2.com":
      MAILTO:joecool@host2.com
     ATTENDEE;DELEGATED-FROM="MAILTO:immud@host3.com":
      MAILTO:ildoit@host1.com

   The following is an example of this property used for specifying
   multiple attendees to an event:

     ORGANIZER:MAILTO:jsmith@host1.com
     ATTENDEE;ROLE=REQ-PARTICIPANT;ATTSTAT=TENTATIVE;CN=Henry
     ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;CN=Henry Cabot
      :MAILTO:hcabot@host2.com
     ATTENDEE;ROLE=REQ-PARTICIPANT;DELEGATED-FROM="MAILTO:bob@host.com"
      ;ATTSTAT=ACCEPTED;CN=Jane Doe: MAILTO:jdoe@host1.com
      ;PARTSTAT=ACCEPTED;CN=Jane Doe:MAILTO:jdoe@host1.com

   The following is an example of this property with a URI to the
   directory information associated with the attendee:

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     ATTENDEE;CN=John Smith;DIR="ldap://host.com:6666/o=eDABC%
      20Industries,c=3DUS??(cn=3DBJim%20Dolittle)":MAILTO:jimdo@
      host1.com

   The following is an example of this property with "delegatee" and
   "delegator" information for an event:

     ORGANIZER;CN=John Smith:MAILTO:jsmith@host.com
     ATTENDEE;ROLE=REQ-PARTICIPANT;ATTSTAT=TENTATIVE;DELEGATED-FROM=
     ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;DELEGATED-FROM=
      "MAILTO:iamboss@host2.com";CN=Henry Cabot:MAILTO:hcabot@
      host2.com
     ATTENDEE;ROLE=NON-PARTICIPANT;ATTSTAT=DELEGATED;DELEGATED-TO=
     ATTENDEE;ROLE=NON-PARTICIPANT;PARTSTAT=DELEGATED;DELEGATED-TO=
      "MAILTO:hcabot@host2.com";CN=The Big Cheese:MAILTO:iamboss
      @host2.com
     ATTENDEE;ROLE=REQ-PARTICIPANT;ATTSTAT=ACCEPTED;CN=Jane
     ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;CN=Jane Doe
      :MAILTO:jdoe@host1.com

   Example: The following is an example of this property's use when
   another calendar user is acting on behalf of the "Attendee":

     ATTENDEE;SENT-BY=MAILTO:jan_doe@host1.com;CN=John Smith:MAILTO:
      jsmith@host1.com

4.8.4.2 Contact

   Property Name: CONTACT

   Purpose: The property is used to represent contact information or
   alternately a reference to contact information associated with the
   calendar component.

   Value Type: TEXT

   Property Parameters: Non-standard, alternate text representation and
   language property parameters can be specified on this property.

   Conformance: The property MAY only can be specified in a "VEVENT",
   "VTODO" and "VTODO",
   "VJOURNAL" and "VFREEBUSY" calendar component in an iCalendar object. component.

   Description: The property value consists of textual contact
   information. An alternative representation for the property value MAY can
   also be specified that refers to a URI pointing to an alternate form,
   such as a vCard, for the contact information.

   Only the "ALTREP" or "LANGUAGE" property parameters MAY be specified
   on this property.

   Format Definition: The property is defined by the following notation:

     contact    = "CONTACT" [contparam] contparam ":" [WSP] text CRLF

     contparam  = [";" [WSP] altrepparm] altrepparam] [";" [WSP] languageparm] languageparam]
                  *(";" xparam)

   Example: The following is an example of this property referencing
   textual contact information:

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     CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

   The following is an example of this property with an alternate
   representation of a LDAP URI to a directory entry containing the
   contact information:

     CONTACT;ALTREP="ldap://host.com:6666/o=3DABC%20Industries\,
      c=3DUS??(cn=3DBJim%20Dolittle)":Jim Dolittle\, ABC Industries\,
      +1-919-555-1234

   The following is an example of this property with an alternate
   representation of a MIME body part containing the contact
   information, such as a vCard embedded in a [MIME-DIR] content-type:

     CONTACT;ALTREP="CID=<part3.msg970930T083000SILVER@host.com>":Jim
       Dolittle\, ABC Industries\, +1-919-555-1234

   The following is an example of this property referencing a network
   resource, such as a vCard object containing the contact information:

     CONTACT;ALTREP="http://host.com/pdi/jdoe.vcf":Jim
       Dolittle\, ABC Industries\, +1-919-555-1234

4.8.4.3 Organizer

   Property Name: ORGANIZER

   Purpose: The property defines the organizer for a calendar component.

   Value Type: CAL-ADDRESS

   Property Parameters: Non-standard, language, common name, directory
   entry reference, sent by property parameters can be specified on this
   property.

   Conformance: This property MUST be specified in an iCalendar object
   that specifies a group scheduled calendar entity. This property MUST
   be specified in an iCalendar object that specifies the publication of
   a calendar user's busy time. This property MUST not NOT be specified in
   an iCalendar object that specifies only a time zone definition or
   that defines calendar entities that are not group scheduled entities,
   but are entities only on a single user's calendar.

   Description: The property is specified within the "VEVENT", "VTODO",
   "VJOURNAL calendar components to specify the organizer of a group
   scheduled calendar entity. The property is specified within the
   "VFREEBUSY" calendar component to specify the calendar user
   requesting the free or busy time. When publishing a "VFREEBUSY"
   calendar component, the property is used to specify the calendar that
   the published busy time came from.

   The property has the property parameters CN, for specifying the
   common or display name associated with the "Organizer", DIR, for
   specifying a pointer to the directory information associated with the

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   "Organizer", SENT-BY, for specifying another calendar user that is
   acting on behalf of the "Organizer". No other The non-standard parameters MAY may
   also be specified on this property. If the LANGUAGE property
   parameter is specified, the identified language applies to the CN
   parameter value.

   Format Definition: The property is defined by the following notation:

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     organizer  = "ORGANIZER" [orgparam] orgparam ":" [WSP]
                  cal-address CRLF

     orgparam   = [";" [WSP] "CN" "=" param-value] cnparam] [";" [WSP] "DIR" "=" DQUOTE uri DQUOTE]
                  proxyparam

     proxyparam = (";" [WSP] "SENT-BY" "=" DQUOTE cal-address DQUOTE) dirparam] [";" sentbyparam]
                  [";" languageparam] *(";" xparam)

   Example: The following is an example of this property:

     ORGANIZER;CN=John Smith:MAILTO:jsmith@host1.com

   The following is an example of this property with a pointer to the
   directory information associated with the organizer:

     ORGANIZER;CN=JohnSmith;DIR="ldap://host.com:6666/o=3DDC%20Associ
      ates,c=3DUS??(cn=3DJohn%20Smith)":MAILTO:jsmith@host1.com

   The following is an example of this property used by another calendar
   user who is acting on behalf of the organizer, with responses
   intended to be sent back to the organizer, not the other calendar
   user:

     ORGANIZER;SENT-BY="MAILTO:jane_doe@host.com":
      MAILTO:jsmith@host1.com

4.8.4.4 Recurrence ID

   Property Name: RECURRENCE-ID

   Purpose: This property is used in conjunction with the "UID" and
   "SEQUENCE" property to identify a specific instance of a recurring
   "VEVENT", "VTODO" or "VJOURNAL" calendar component. The property
   value is the effective value of the "DTSTART" property of the
   recurrence instance.

   Value Type: The default value type for this property is DATE-TIME.
   The time format MAY BE can be any of the valid forms defined for a DATE-TIME
   value type. See DATE-TIME value type definition for specific
   interpretations of the various forms. The value type MAY can be reset to
   DATE.

   Property Parameters: Non-standard property, value data type, time
   zone identifier and recurrence identifier range parameters can be
   specified on this property.

   Conformance: This property MAY can be specified in an iCalendar object
   containing a recurring calendar component.

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   Description: The full range of calendar components specified by a
   recurrence set is referenced by referring to just the "UID" property
   value corresponding to the calendar component. The "RECURRENCE-ID"
   property allows the reference to an individual instance within the
   recurrence set.

   If the value of the "DTSTART" property is a DATE type value, then the
   value MUST be the calendar date for the recurrence instance.

Dawson/Stenerson                   78            Expires September 1998

   The date/time value is set to the time when the original recurrence
   instance would occur - - meaning that if the intent is to change a
   Friday meeting to Thursday, the date/time is still set to the
   original Friday meeting.

   The "RECURRENCE-ID" property is used in conjunction with the "UID"
   and "SEQUENCE" property to identify a particular instance of a
   recurring event, to-do or journal. For a given pair of "UID" and
   "SEQUENCE" property values, the "RECURRENCE-ID" value for a
   recurrence instance is fixed. When the definition of the recurrence
   set for a calendar component changes, and hence the "SEQUENCE"
   property value changes, the "RECURRENCE-ID" for a given recurrence
   instance might also change.The "RANGE" parameter is used to specify
   the effective range of recurrence instances from the instance
   specified by the "RECURRENCE-ID" property value. The default value
   for the range parameter is the single recurrence instance only. The
   value can also be "THISANDPRIOR" to indicate a range defined by the
   given recurrence instance and all prior instances or the value can be
   "THISANDFUTURE" to indicate a range defined by the given recurrence
   instance and all subsequent instances.

   Only the "VALUE" property parameter and the property-specific "RANGE"
   parameter MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     recurid    = "RECURRENCE-ID" *(";" [WSP] parameter)
                  [";" [WSP] rangeparm] ":" [WSP] [date-time / date]
        ;Value must match value type.

     recurid    = "RECURRENCE-ID" [ridparam] [rangeparm] ridparam ":" [WSP] ridval CRLF

     ridparam   = ";" [WSP] [";" "VALUE" "=" ("DATE-TIME" / "DATE" /
                / "PERIOD")

     rangeparm  = ";" [WSP] "RANGE" "=" ("THISANDPRIOR"
                / "THISANDFUTURE") "DATE)]
                  [";" tzidparam] [";" rangeparam]
                  *(";" xparam)

     ridval     = date-time / date / period
     ;Value MUST match value type

   Example: The following are examples of this property:

     RECURRENCE-ID;VALUE=DATE:19960401

     RECURRENCE-ID;RANGE=THISANDFUTURE:19960120T120000Z

4.8.4.5 Related To

   Property Name: RELATED-TO

   Purpose: The property is used to represent a relationship or
   reference between one calendar component and another.

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   Value Type: TEXT

   Property Parameters: Non-standard and relationship type property
   parameters can be specified on this property.

   Conformance: The property MAY only can be specified once in the "VEVENT",
   "VTODO" and "VJOURNAL" calendar components.

   Description: The property value consists of the persistent, globally
   unique identifier of another calendar component. This value would be
   represented in a calendar component by the "UID" property.

   By default, the property value points to another calendar component
   that has a PARENT relationship to the referencing object. The
   "RELTYPE" property parameter is used to either explicitly state the
   default PARENT relationship type to the referenced calendar component
   or to override the default PARENT relationship type and specify
   either a CHILD or SIBLING relationship. The PARENT relationship
   indicates that the calendar component is a subordinate of the
   referenced calendar component. The CHILD relationship indicates that
   the calendar component is a superior of the referenced calendar
   component. The SIBLING relationship indicates that the calendar
   component is a peer of the referenced calendar component.

   Changes to a calendar component referenced by this property MAY can have
   an implied implicit impact to on the related calendar component. For example, if
   a group event changes its start or end date or time, then the
   related, dependent events will need to have their start and end dates
   changed in a corresponding way. Similarly, if a PARENT calendar
   component is canceled or deleted, then there is an implied impact to
   the related CHILD calendar components. This property is intended only
   to provide information on the relationship of calendar components. It
   is up to the target calendar system to maintain any property
   implications of this relationship.

   Only the property specific "RELTYPE" parameter MAY be specified on
   this property.

   Format Definition: The property is defined by the following notation:

     related    = "RELATED-TO" [";" [WSP] relparam) [relparam] ":" [WSP] text CRLF

     relparam   = "RELTYPE" "="
                  "PARENT"      ; Parent relationship. Default.
                / "CHILD"       ; Child relationship.
                / "SIBLING"     ; Sibling relationship. [";" reltypeparam]
                  *(";" xparm)

   The following is an example of this property:

     RELATED-TO:<jsmith.part7.19960817T083000.xyzMail@host3.com>

     RELATED-TO:<19960401-080045-4000F192713-0052@host1.com>

4.8.4.6 Uniform Resource Locator

   Property Name: URL

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   Purpose: This property defines a Uniform Resource Locator (URL)
   associated with the iCalendar object.

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   Value Type: URI

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY can be specified once in the "VEVENT",
   "VTODO", "VJOURNAL" and "VFREEBUSY" calendar components.

   Description: This property may be used in a calendar component to
   convey a location where a more dynamic rendition of the calendar
   information associated with the calendar component can be found. This
   memo does not attempt to standardize the form of the URI, nor the
   format of the resource pointed to by the property value. If the

   No URL
   property parameter MAY be specified on this property. and Content-Location MIME header are both specified, they
   MUST point to the same resource.

   Format Definition: The property is defined by the following notation:

     url        = "URL" urlparam ":" [WSP] uri CRLF

     urlparam   = *(";" xparam)

   Example: The following is an example of this property:

     URL:http://abc.com/pub/calendars/jsmith/mytime.or3

     URL:http://abc.com/pub/calendars/jsmith/mytime.ics

4.8.4.7 Unique Identifier

   Property Name: UID

   Purpose: This property defines the persistent, globally unique
   identifier for the calendar component.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MUST be specified in the "VEVENT", "VTODO",
   "VJOURNAL" and "VFREEBUSY" calendar components.

   Description: The UID itself MUST be a globally unique identifier. The
   generator of the identifier MUST guarantee that the identifier is
   unique. There are several algorithms that can be used to accomplish
   this. The identifier is RECOMMENDED to be the identical syntax to the
   [RFC 822] addr-spec. A good method to assure uniqueness is to put the
   domain name or a domain literal IP address of the host on which the
   identifier was created on the right hand side of the "@", and on the
   left hand side, put a combination of the current calendar date and
   time of day (i.e., formatted in as a DATE-TIME value) along with some
   other currently unique (perhaps sequential) identifier available on
   the system (for example, a process id number). Using a date/time
   value on the left hand side and a domain name or domain literal on
   the right hand side makes it possible to guarantee uniqueness since

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   no two hosts should be using the same domain name or IP address at
   the same time. Though other algorithms will work, it is RECOMMENDED
   that the right hand side contain some domain identifier (either of
   the host itself or otherwise) such that the generator of the message

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   identifier can guarantee the uniqueness of the left hand side within
   the scope of that domain.

   This is the method for correlating scheduling messages with the
   referenced "VEVENT", "VTODO", or "VJOURNAL" calendar component.

   The full range of calendar components specified by a recurrence set
   is referenced by referring to just the "UID" property value
   corresponding to the calendar component. The "RECURRENCE-ID" property
   allows the reference to an individual instance within the recurrence
   set.

   This property is an important method for group scheduling
   applications to match requests with later replies, modifications or
   deletion requests. Calendaring and scheduling applications MUST
   generate this property in "VEVENT", "VTODO" and "VJOURNAL" calendar
   components to assure interoperability with other group scheduling
   applications. This identifier is created by the calendar system that
   generates an iCalendar object.

   Implementations MUST be able to receive and persist values of at
   least 255 characters for this property.

   No property parameter MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     uid        = "UID" uidparam ":" [WSP] text CRLF

     uidparam   = *(";" xparam)

   Example: The following is an example of this property:

     UID:19960401T080045Z-4000F192713-0052@host1.com

4.8.5   Recurrence Component Properties

   The following properties specify recurrence information in calendar
   components.

4.8.5.1 Exception Date/Times

   Property Name: EXDATE

   Purpose: This property defines the list of date/time exceptions for a
   recurring calendar component.

   Value Type: The default value type for this property is DATE-TIME.
   The value type MAY can be reset to DATE.

   Property Parameters: Non-standard, value data type and time zone
   identifier property parameters can be specified on this property.

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   Conformance: This property MAY can be specified in an iCalendar object
   that includes a recurring calendar component.

   Description: The exception dates, if specified, is used in computing
   the recurrence set. The recurrence set is the complete set of
   recurrence instances for a calendar component. The recurrence set is

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   generated by considering the initial "DTSTART" property along with
   the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
   within the iCalendar object. The "DTSTART" property defines the first
   instance in the recurrence set. Multiple instances of the "RRULE" and
   "EXRULE" properties MAY can also be specified to define more
   sophisticated recurrence sets. The final recurrence set is generated
   by gathering all of the start date-times generated by any of the
   specified "RRULE" and "RDATE" properties, and then excluding any
   start date and times which fall within the union of start date and
   times generated by any specified "EXRULE" and "EXDATE" properties.
   This implies that start date and times within exclusion related
   properties (i.e., "EXDATE" and "EXRULE") take precedence over those
   specified by inclusion properties (i.e., "RDATE" and "RRULE"). Where
   duplicate instances are generated by the "RRULE" and "RDATE"
   properties, only one recurrence is considered. Duplicate instances
   are ignored.

   The "EXDATE" property MAY can be used to exclude the value specified in
   "DTSTART". However, in such cases the original "DTSTART" date MUST
   still be maintained by the calendaring and scheduling system because
   the original "DTSTART" value has inherent usage dependencies by other
   properties such as the "RECURRENCE-ID".

   Only the "VALUE" and "TZID" property parameters MAY be specified on
   this property. The "TZID" property parameter MAY only be specified
   when the value type is DATE-TIME.

   Format Definition: The property is defined by the following notation:

     exdate     = "EXDATE" [exdtparam] exdtparam ":" [WSP] exdtval *("," exdtval) CRLF

     exdtparam  = [";" [WSP] "VALUE" "=" "DATE-TIME"] ("DATE-TIME" / "DATE")]
                  [";" [WSP] "TZID" "=" paramtext]

     exdtparam  =/ ";" [WSP] "VALUE" "=" "DATE" tzidparam]
                  *(";" xparam)

     exdtval    = date-time / date
     ;Value MUST match value type

   Example: The following is an example of this property:

     EXDATE:19960402T010000Z,19960403T010000Z,19960404T010000Z

4.8.5.2 Exception Rule

   Property Name: EXRULE

   Purpose: This property defines a rule or repeating pattern for an
   exception to a recurrence set.

   Value Type: RECUR

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   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY only can be specified in the "VEVENT", "VTODO"
   or "VJOURNAL" calendar components.

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   Description: The exception rule, if specified, is used in computing
   the recurrence set. The recurrence set is the complete set of
   recurrence instances for a calendar component. The recurrence set is
   generated by considering the initial "DTSTART" property along with
   the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
   within the iCalendar object. The "DTSTART" defines the first instance
   in the recurrence set. Multiple instances of the "RRULE" and "EXRULE"
   properties MAY can also be specified to define more sophisticated
   recurrence sets. The final recurrence set is generated by gathering
   all of the start date-times generated by any of the specified "RRULE"
   and "RDATE" properties, and excluding any start date and times which
   fall within the union of start date and times generated by any
   specified "EXRULE" and "EXDATE" properties. This implies that start
   date and times within exclusion related properties (i.e., "EXDATE"
   and "EXRULE") take precedence over those specified by inclusion
   properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
   generated by the "RRULE" and "RDATE" properties, only one recurrence
   is considered. Duplicate instances are ignored.

   The "EXRULE" property MAY can be used to exclude the value specified in
   "DTSTART". However, in such cases the original "DTSTART" date MUST
   still be maintained by the calendaring and scheduling system because
   the original "DTSTART" value has inherent usage dependencies by other
   properties such as the "RECURRENCE-ID".

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     exrule     = "EXRULE" exrparam ":" [WSP] recur CRLF

     exrparam   = *(";" xparam)

   Example: The following are examples of this property. Except every
   other week, on Tuesday and Thursday for 4 occurrences:

     EXRULE:FREQ=WEEKLY;COUNT=4;INTERVAL=2;BYDAY=TU,TH

   Except daily for 10 occurrences:

     EXRULE:FREQ=DAILY;COUNT=10

   Except yearly in June and July for 8 occurrences:

     EXRULE:FREQ=YEARLY;COUNT=8;BYMONTH=6,7

   The data type for this property is RECUR.

4.8.5.3 Recurrence Date/Times

   Property Name: RDATE

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   Purpose: This property defines the list of date/times for a
   recurrence set.

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   Value Type: The default value type for this property is DATE-TIME.
   The value type MAY can be reset to DATE or PERIOD.

   Property Parameters: Non-standard, value data type and time zone
   identifier property parameters can be reset to DATE or PERIOD. specified on this property.

   Conformance: The property MAY only can appear within the "VEVENT", "VTODO",
   "VJOURNAL" or and "VTIMEZONE" calendar components.

   Description: This property MAY can appear along with the "RRULE" property
   to define an aggregate set of repeating occurrences. When they both
   appear in an iCalendar object, the recurring events are defined by
   the union of occurrences defined by both the "RDATE" and "RRULE".

   The recurrence dates, if specified, is used in computing the
   recurrence set. The recurrence set is the complete set of recurrence
   instances for a calendar component. The recurrence set is generated
   by considering the initial "DTSTART" property along with the "RRULE",
   "RDATE", "EXDATE" and "EXRULE" properties contained within the
   iCalendar object. The "DTSTART" property defines the first instance
   in the recurrence set. Multiple instances of the "RRULE" and "EXRULE"
   properties MAY can also be specified to define more sophisticated
   recurrence sets. The final recurrence set is generated by gathering
   all of the start date-times generated by any of the specified "RRULE"
   and "RDATE" properties, and excluding any start date and times which
   fall within the union of start date and times generated by any
   specified "EXRULE" and "EXDATE" properties. This implies that start
   date and times within exclusion related properties (i.e., "EXDATE"
   and "EXRULE") take precedence over those specified by inclusion
   properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
   generated by the "RRULE" and "RDATE" properties, only one recurrence
   is considered. Duplicate instances are ignored.

   Only the "VALUE" and "TZID" property parameters MAY be specified on
   this property. The "TZID" property parameter MAY only be specified
   when the value type is DATE-TIME.

   Format Definition: The property is defined by the following notation:

     rdate      = "RDATE" [rdtparam] rdtparam ":" [WSP] rdtval *("," [WSP] rdtval) CRLF

     rdtparam   = [";" [WSP] "VALUE" "=" "DATE-TIME"]
                  [";" [WSP] "TZID" "=" paramtext]

     rdtparam   =/ ";" [WSP] "VALUE" "=" ("DATE-TIME" / "DATE"

     rdtparam   =/ ";" [WSP] "VALUE" "=" "PERIOD"
                  / "PERIOD")]
                  [";" tzidparam]
                  *(";" xparam)

     rdtval     = date-time / date / period
     ;Value MUST match value type

   Example: The following are examples of this property:

     RDATE:19970714T123000Z

     RDATE;TZID=EST:19970714T083000

     RDATE;TZID=US-EASTERN:19970714T083000

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     RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z,
      19960404T010000Z/PT3H

     RDATE;VALUE=DATE:19970101,19970120,19970217,19970421
      19970526,19970704,19970901,19971014,19971128,19971129,19971225

4.8.5.4 Recurrence Rule

   Property Name: RRULE

   Purpose: This property defines a rule or repeating pattern for a
   recurring events, to-dos, or time zone definitions.

   Value Type: RECUR

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY can be specified one or more times in
   recurring "VEVENT", "VTODO" and "VJOURNAL" calendar components. It
   MAY
   can also be specified once in each STANDARD or DAYLIGHT sub-component
   of the "VTIMEZONE" calendar component.

   Description: The recurring rule, if specified, is used in computing
   the recurrence set. The recurrence set is the complete set of
   recurrence instances for a calendar component. The recurrence set is
   generated by considering the initial "DTSTART" property along with
   the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
   within the iCalendar object. The "DTSTART" property defines the first
   instance in the recurrence set. Multiple instances of the "RRULE" and
   "EXRULE" properties MAY can also be specified to define more
   sophisticated recurrence sets. The final recurrence set is generated
   by gathering all of the start date-times generated by any of the
   specified "RRULE" and "RDATE" properties, and excluding any start
   date and times which fall within the union of start date and times
   generated by any specified "EXRULE" and "EXDATE" properties. This
   implies that start date and times within exclusion related properties
   (i.e., "EXDATE" and "EXRULE") take precedence over those specified by
   inclusion properties (i.e., "RDATE" and "RRULE"). Where duplicate
   instances are generated by the "RRULE" and "RDATE" properties, only
   one recurrence is considered. Duplicate instances are ignored.

   The "DTSTART" and "DTEND" property pair or "DTSTART" and "DURATION"
   property pair, specified within the iCalendar object defines the
   first instance of the recurrence. When used with a recurrence rule,
   the "DTSTART" and "DTEND" properties MUST be specified in local time
   and the appropriate set of "VTIMEZONE" calendar components MUST be
   included. For detail on the usage of the "VTIMEZONE" calendar
   component, see the "VTIMEZONE" calendar component definition.

   Any duration associated with the iCalendar object applies to all
   members of the generated recurrence. Any modified duration for
   specific recurrences would have to be explicitly specified using the
   "RDATE" property.

   No property parameters MAY be specified on this property.

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   Format Definition: This property is defined by the following
   notation:

     rrule      = "RRULE" rrulparam ":" [WSP] recur CRLF

     rrulparam  = *(";" xparam)

   Example: All examples assume the Eastern United States time zone.

   Daily for 10 occurrences:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=DAILY;COUNT=10

     ==> (1997 9AM 9:00 AM EDT)September 2-11

   Daily until 12/24/97: December 24, 1997:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=DAILY;UNTIL=19971224T000000Z

     ==> (1997 9AM 9:00 AM EDT)September 2-30;October 1-25
         (1997 9AM 9:00 AM EST)October 26-31;November 1-30;December 1-23

   Every other day - forever:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=DAILY;INTERVAL=2
     ==> (1997 9AM 9:00 AM EDT)September2,4,6,8...24,26,28,30;
          October 2,4,6...20,22,24
         (1997 9AM 9:00 AM EST)October 26,28,30;November 1,3,5,7...25,27,29;
          Dec 1,3,...

   Every 10 days, 5 occurrences:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5

     ==> (1997 9AM 9:00 AM EDT)September 2,12,22;October 2,12

   Everyday in January, for 3 years:

     DTSTART;TZID=America-New York:19980101T090000
     RRULE;TZID=America-New York:FREQ=YEARLY;UNTIL:20000131T090000;
     RRULE:FREQ=YEARLY;UNTIL=20000131T090000Z;
      BYMONTH=1;BYDAY=SU,MO,TU,WE,TH,FR,SA
     or
     RRULE;TZID=America-New York:FREQ=DAILY;UNTIL:20000131T090000;
      BYMONTH=1
     RRULE:FREQ=DAILY;UNTIL=20000131T090000Z;BYMONTH=1

     ==> (1998 9AM 9:00 AM EDT)January 1-31
         (1999 9AM 9:00 AM EDT)January 1-31
         (2000 9AM 9:00 AM EDT)January 1-31

   Weekly for 10 occurrences

     DTSTART;TZID=America-New York:19970902T090000

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     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=WEEKLY;COUNT=10

     ==> (1997 9AM 9:00 AM EDT)September 2,9,16,23,30;October 7,14,21
         (1997 9AM 9:00 AM EST)October 28;November 4

   Weekly until 12/24/94 December 24, 1997

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z

     ==> (1997 9AM 9:00 AM EDT)September 2,9,16,23,30;October 7,14,21
         (1997 9AM 9:00 AM EST)October 28;November 4,11,18,25;
                       December 2,9,16,23

   Every other week - forever:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU

     ==> (1997 9AM 9:00 AM EDT)September 2,16,30;October 14
         (1997 9AM 9:00 AM EST)October 28;November 11,25;December 9,23
         (1998 9AM 9:00 AM EST)January 6,20;February
     ...

   Weekly on Tuesday and Thursday for 5 weeks:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE;TZID=America-New York:FREQ=WEEKLY;UNTIL=19971007T000000;
      WKST=SU;BYDAY=TU,TH
     RRULE:FREQ=WEEKLY;UNTIL=19971007T000000Z;WKST=SU;BYDAY=TU,TH
     or
     RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH

     ==> (1997 9AM 9:00 AM EDT)September 2,4,9,11,16,18,23,25,30;October 2

   Every other week on Monday, Wednesday and Friday until 12/24/97, December 24,
   1997, but starting on Tuesday, 9/2/97: September 2, 1997:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE;TZID=America-New York:FREQ=WEEKLY;INTERVAL=2;UNTIL=
      19971224T000000;WKST=SU;BYDAY=MO,WE,FR
     RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000Z;WKST=SU;
      BYDAY=MO,WE,FR
     ==> (1997 9AM 9:00 AM EDT)September 2,3,5,15,17,19,29;October
     1,3,13,15,17
         (1997 9AM 9:00 AM EST)October 27,29,31;November 10,12,14,24,26,28;
                           December 8,10,12,22

   Every other week on Tuesday and Thursday, for 8 occurrences:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH

     ==> (1997 9AM 9:00 AM EDT)September 2,4,16,18,30;October 2,14,16

   Monthly on the 1st Friday for ten occurrences:

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     DTSTART;TZID=America-New York:19970905T090000
     RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR

     ==> (1997 9AM 9:00 AM EDT)September 5;October 3
         (1997 9AM 9:00 AM EST)November 7;Dec 5
         (1998 9AM 9:00 AM EST)January 2;February 6;March 6;April 3
         (1998 9AM EDT)MAY 9:00 AM EDT)May 1;June 5

   Monthly on the 1st Friday until 12/24/94: December 24, 1997:

     DTSTART;TZID=America-New York:19970905T090000
     RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;BYDAY=1FR

     ==> (1997 9AM 9:00 AM EDT)September 5;October 3
         (1997 9AM 9:00 AM EST)November 7;December 5

   Every other month on the 1st and last Sunday of the month for 10
   occurrences:

     DTSTART;TZID=America-New York:19970907T090000
     RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU

     ==> (1997 9AM 9:00 AM EDT)September 7,28
         (1997 9AM 9:00 AM EST)November 2,30
         (1998 9AM 9:00 AM EST)January 4,25;March 1,29
         (1998 9AM EDT)MAY 9:00 AM EDT)May 3,31

   Monthly on the second to last Monday of the month for 6 months:

     DTSTART;TZID=America-New York:19970922T090000
     RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO

     ==> (1997 9AM 9:00 AM EDT)September 22;October 20
         (1997 9AM 9:00 AM EST)November 17;December 22
         (1998 9AM 9:00 AM EST)January 19;February 16

   Monthly on the third to the last day of the month, forever:

     DTSTART;TZID=America-New York:19970928T090000
     RRULE:FREQ=MONTHLY;BYMONTHDAY=-3

     ==> (1997 9AM 9:00 AM EDT)September 28
         (1997 9AM 9:00 AM EST)October 29;November 28;December 29
         (1998 9AM 9:00 AM EST)January 29;February 26
     ...

   Monthly on the 2nd and 15th of the month for 10 occurrences:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15

     ==> (1997 9AM 9:00 AM EDT)September 2,15;October 2,15
         (1997 9AM 9:00 AM EST)November 2,15;December 2,15
         (1998 9AM 9:00 AM EST)January 2,15

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   Monthly on the first and last day of the month for 10 occurrences:

     DTSTART;TZID=America-New York:19970930T090000
     RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1

     ==> (1997 9AM 9:00 AM EDT)September 30;October 1
         (1997 9AM 9:00 AM EST)October 31;November 1,30;December 1,31
         (1998 9AM 9:00 AM EST)January 1,31;February 1

   Every 18 months on the 10th thru 15th of the month for 10
   occurrences:

     DTSTART;TZID=America-New York:19970910T090000
     RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;BYMONTHDAY=10,11,12,13,14,
      15

     ==> (1997 9AM 9:00 AM EDT)September 10,11,12,13,14,15
         (1999 9AM 9:00 AM EST)March 10,11,12,13

   Every Tuesday, every other month:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU

     ==> (1997 9AM 9:00 AM EDT)September 2,9,16,23,30
         (1997 9AM 9:00 AM EST)November 4,11,18,25
         (1998 9AM 9:00 AM EST)January 6,13,20,27;March 3,10,17,24,31
     ...

   Yearly in June and July for 10 occurrences:

     DTSTART;TZID=America-New York:19970610T090000
     RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7

     ==> (1997 9AM 9:00 AM EDT)June 10;July 10
         (1998 9AM 9:00 AM EDT)June 10;July 10
         (1999 9AM 9:00 AM EDT)June 10;July 10
         (2000 9AM 9:00 AM EDT)June 10;July 10
         (2001 9AM 9:00 AM EDT)June 10;July 10
     Note: Since none of the BYDAY, BYMONTHDAY or BYYEARDAY components
     are specified, the day is gotten from DTSTART

   Every other year on January, February, and March for 10 occurrences:

     DTSTART;TZID=America-New York:19970310T090000
     RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;BYMONTH=1,2,3

     ==> (1997 9AM 9:00 AM EST)March 10
         (1999 9AM 9:00 AM EST)January 10;February 10;March 10
         (2001 9AM 9:00 AM EST)January 10;February 10;March 10
         (2003 9AM 9:00 AM EST)January 10;February 10;March 10

   Every 3rd year on the 1st, 100th and 200th day for 10 occurrences:

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     DTSTART;TZID=America-New York:19970101T090000
     RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;BYYEARDAY=1,100,200

     ==> (1997 9AM 9:00 AM EST)January 1
         (1997 9AM 9:00 AM EDT)April 10;July 19
         (2000 9AM 9:00 AM EST)January 1
         (2000 9AM 9:00 AM EDT)April 9;July 18
         (2003 9AM 9:00 AM EST)January 1
         (2003 9AM 9:00 AM EDT)April 10;July 19
         (2006 9AM 9:00 AM EST)January 1

   Every 20th Monday of the year, forever:

     DTSTART;TZID=America-New York:19970519T090000
     RRULE:FREQ=YEARLY;BYDAY=20MO

     ==> (1997 9AM EDT)MAY 9:00 AM EDT)May 19
         (1998 9AM EDT)MAY 9:00 AM EDT)May 18
         (1999 9AM EDT)MAY 9:00 AM EDT)May 17
     ...

   Monday of Week No. 20, week number 20 (where the default start of the week is
   Monday), forever:

     DTSTART;TZID=America-New York:19970512T090000
     RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO

     ==> (1997 9AM EDT)MAY 9:00 AM EDT)May 12
         (1998 9AM EDT)MAY 9:00 AM EDT)May 11
         (1999 9AM EDT)MAY 9:00 AM EDT)May 17
     ...

   Every Thursday in March, forever:

     DTSTART;TZID=America-New York:19970313T090000
     RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH

     ==> (1997 9AM 9:00 AM EST)March 13,20,27
         (1998 9AM 9:00 AM EST)March 5,12,19,26
         (1999 9AM 9:00 AM EST)March 4,11,18,25
     ...

   Every Thursday, but only during summer months, June, July, and August, forever:

     DTSTART;TZID=America-New York:19970605T090000
     RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8

     ==> (1997 9AM 9:00 AM EDT)June 5,12,19,26;July 3,10,17,24,31;
                       August 7,14,21,28
         (1998 9AM 9:00 AM EDT)June 4,11,18,25;July 2,9,16,23,30;
                       August 6,13,20,27
         (1999 9AM 9:00 AM EDT)June 3,10,17,24;July 1,8,15,22,29;
                       August 5,12,19,26
     ...

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   Every Friday the 13th, forever:

     DTSTART;TZID=America-New York:19970902T090000
     EXDATE;TZID=America-New York:19970902T090000
     RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13

     ==> (1998 9AM 9:00 AM EST)February 13;March 13;November 13
         (1999 9AM 9:00 AM EDT)August 13
         (2000 9AM 9:00 AM EDT)October 13
     ...

   The first Saturday that follows the first Sunday of the month,
   forever:

     DTSTART;TZID=America-New York:19970913T090000
     RRULE:FREQ=MONTHLY;BYDAY=SA;BYMONTHDAY=7,8,9,10,11,12,13

     ==> (1997 9AM 9:00 AM EDT)September 13;October 11
         (1997 9AM 9:00 AM EST)November 8;December 13
         (1998 9AM 9:00 AM EST)January 10;February 7;March 7
         (1998 9AM 9:00 AM EDT)April 11;MAY 11;May 9;June 13...
     ...

   Every four years, the first Tuesday after a Monday in November,
   forever (U.S. Presidential Election day):

     DTSTART;TZID=America-New York:19961105T090000
     RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;BYDAY=TU;BYMONTHDAY=2,3,4,
      5,6,7,8

     ==> (1996 9AM 9:00 AM EST)November 5
         (2000 9AM 9:00 AM EST)November 7
         (2004 9AM 9:00 AM EST)November 2
     ...

   The 3rd instance into the month of one of Tuesday, Wednesday or
   Thursday, for the next 3 months:

     DTSTART;TZID=America-New York:19970904T090000
     RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;BYSETPOS=3

     ==> (1997 9AM 9:00 AM EDT)September 4;October 7
         (1997 9AM 9:00 AM EST)November 6

   The 2nd to last weekday of the month:

     DTSTART;TZID=America-New York:19970929T090000
     RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-2

     ==> (1997 9AM 9:00 AM EDT)September 29
         (1997 9AM 9:00 AM EST)October 30;November 27;December 30
         (1998 9AM 9:00 AM EST)January 29;February 26;March 30
     ...

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   Every 3 hours from 9AM 9:00 AM to 5PM 5:00 PM on a specific day:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE;TZID=America-New York:FREQ=HOURLY;INTERVAL=3;
      UNTIL=19970902T170000
     RRULE:FREQ=HOURLY;INTERVAL=3;UNTIL=19970902T170000Z

     ==> (September 2, 1997 EDT)09:00,12:00,15:00

   Every 15 minutes for 6 occurrences:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=MINUTELY;INTERVAL=15;COUNT=6

     ==> (September 2, 1997 EDT)09:00,09:15,09:30,09:45,10:00,10:15

   Every hour and a half for 4 occurrences:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4

     ==> (September 2, 1997 EDT)09:00,10:30;12:00;13:30

   Every 20 minutes from 9AM 9:00 AM to 4:40PM 4:40 PM every day:

     DTSTART;TZID=America-New York:19970902T090000
     RRULE:FREQ=DAILY;BYHOUR=9,10,11,12,13,14,15,16;BYMINUTE=0,20,40
     or
     RRULE:FREQ=MINUTELY;INTERVAL=20;BYHOUR=9,10,11,12,13,14,15,16

     ==> (September 2, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
                                ... 16:00,16:20,16:40
         (September 3 3, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
                               ...16:00,16:20,16:40
     ...

   An example where the days generated makes a difference because of
   WKST:

     DTSTART;TZID=America-New York:19970805T090000
     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO

     ==> (1997 EDT)Aug 5,10,19,24

     changing only WKST from MO to SU, yields different results...

     DTSTART;TZID=America-New York:19970805T090000
     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU
     ==> (1997 EDT)August 5,17,19,31

4.8.6   Alarm Component Properties

   The following properties specify alarm information in calendar
   components.

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4.8.6.1 Alarm Type Action

   Property Name: ALARM-TYPE ACTION

   Purpose: This property defines the type of alarm. action to be invoked when an alarm
   is triggered.

   Value Type: TEXT

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MUST be specified once within a "VALARM"
   calendar component.

   Description: Each "VALARM" calendar component is of has a particular
   type. type
   of action associated with it. This property specifies the alarm type. Only the "LANGUAGE"
   property parameter MAY be specified on this property. type of
   action

   Format Definition: The property is defined by the following notation:

     alarm-type

     action     = "ALARM-TYPE" [almtypparam] "ACTION" actionparam ":" [WSP] almtypvalue actionvalue CRLF

     almtypparam

     actionparam        = ";" [WSP] languageparm

     almtypvalue *(";" xparam)

     actionvalue        = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE"
                        / iana-token / x-name

   Example: The following are examples of this property in a "VALARM"
   calendar component:

     CATEGORIES:AUDIO,DISPLAY

     CATEGORIES:PROCEDURE

     ACTION:AUDIO

     ACTION:DISPLAY

     ACTION:PROCEDURE

4.8.6.2 Repeat Count

   Property Name: REPEAT

   Purpose: This property defines the number of time the alarm should be
   repeated, after the initial trigger.

   Value Type: INTEGER

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY only can be specified in a "VALARM" calendar
   component.

   Description: If the alarm triggers more than once, then this property
   MUST be specified; specified along with the "DURATION" property.

   No property parameter MAY be specified on this property.

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   Format Definition: The property is defined by the following notation:

     repeatcnt  = "REPEAT" repparam ":" [WSP] integer CRLF
     ;Default is "0", zero.

Dawson/Stenerson                   94            Expires September 1998

     repparam   = *(";" xparam)

   Example: The following is an example of this property for an alarm
   that repeats 4 additional times with a 5 minute delay after the
   initial triggering of the alarm.:

     REPEAT:4
     DURATION:PT5M

4.8.6.3 Trigger

   Property Name: TRIGGER

   Purpose: This property specifies when an alarm will trigger.

   Value Type: The default value type is DURATION. The value type MAY BE can be
   reset to a DATE-TIME value type. type, in which case the value MUST specify
   a UTC formatted DATE-TIME value.

   Property Parameters: Non-standard, value data type, time zone
   identifier or trigger relationship property parameters can be
   specified on this property. The trigger relationship property
   parameter MUST only be specified when the value type is DURATION.

   Conformance: This property MUST be specified within the "VALARM"
   calendar component.

   Description: Within the "VALARM" calendar component, this property
   defines when the alarm will trigger. The default value type is
   DURATION, specifying a relative time for the trigger of the alarm.
   The default duration is relative to the start of an event or to-do
   that the alarm is associated with. The duration can be explicitly set
   to trigger from either the end or the start of the associated event
   or to-do with the "RELATED" parameter. A value of START will set the
   alarm to trigger off the start of the associated event or to-do. A
   value of END will set the alarm to trigger off the end of the
   associated event or to-do.

   Either a positive or negative duration may be specified for the
   "TRIGGER" property. An alarm with a positive duration is triggered
   before
   after the associated start or end of the event or to-do. An alarm
   with a negative duration is triggered after before the associated start or
   end of the event or to-do.

   This

   The "RELATED" property parameter is not valid if the value type of
   the property is reset to DATE-TIME, in order to specify DATE-TIME (i.e., for an absolute trigger for the
   alarm. date and
   time alarm trigger). If a value type of DATE-TIME is specified, then
   the property value MUST be specified in the UTC time format. If an
   absolute trigger is specified on an alarm for a recurring event or

Dawson/Stenerson                  104             Expires November 1998
   to-do, then the alarm will only trigger for the specified absolute
   date/time, along with any specified repeating instances.

   If the trigger is set relative to START, then the "DTSTART" property
   must be present in the associated "VEVENT" or "VTODO" calendar
   component. If an alarm is specified for an event with the trigger set
   relative to the END, then the "DTEND" property or the "DSTART" and
   "DURATION' properties must be present in the associated "VEVENT"
   calendar component. If the alarm is specified for a to-do with a
   trigger set relative to the END, then either the "DUE" property or
   the "DSTART" and "DURATION' properties must be present in the
   associated "VTODO" calendar component.

Dawson/Stenerson                   95            Expires September 1998

   Alarms specified in an event or to-do that which is defined solely in terms of a
   DATE value type will be triggered relative to midnight 00:00:00 UTC on the
   day prior to the
   specified date. For example, if "DTSTART:19980205, then the a duration
   trigger will be relative to 19980204T240000Z.

   Only the "VALUE" and "TZID" property parameters and property-specific
   "RELATED" parameter MAY be specified on this property. The "TZID"
   property parameter MAY only be specified when the value type is DATE-
   TIME. to19980205T000000Z.

   Format Definition: The property is defined by the following notation:

     trigger    = "TRIGGER" (trigrel / trigabs)

     trigrel    = ([";" [WSP] [";" "VALUE" "=" "DURATION"]
                  ";" [WSP] "RELATED" "=" ("START" / "END"))
                   [";" trigrelparam] *(";" xparam)
                  ":" [WSP] (["+"] / "-")  duration

     trigabs    = (";" [WSP] ";" "VALUE" "=" "DATE-TIME" *(";" xparam)
                  ":" [WSP] date-time) date-time

   Example: A trigger set 15 minutes relative prior to the start of the event or
   to-do.

     TRIGGER:P15M

     TRIGGER:-P15M

   A trigger set 5 minutes relative to after the end of the event or to-do.

     TRIGGER;RELATED=END:P5M

   A trigger set to an absolute date/time.

     TRIGGER;VALUE=DATE-TIME:19980101T050000Z

4.8.7   Change Management Component Properties

   The following properties specify change management information in
   calendar components.

4.8.7.1 Date/Time Created

   Property Name: CREATED

   Purpose: This property specifies the date and time that the calendar
   information was created in by the calendar user agent. agent in the calendar
   store.

Dawson/Stenerson                  105             Expires November 1998
        Note: This is analogous to the creation date and time for a file
        in the file system.

   Value Type: DATE-TIME

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MAY can be specified once in any of the "VEVENT", "VTODO"
   and "VJOURNAL" calendar components. The property MAY only be specified once.

   Description: The date and time is a an UTC value.

   No property parameters MAY be specified on this property.

Dawson/Stenerson                   96            Expires September 1998

   Format Definition: The property is defined by the following notation:

     created    = "CREATED" creaparam ":" [WSP] date-time CRLF

     creaparam  = *(";" xparam)

   Example: The following is an example of this property:

     CREATED:19960329T133000Z

4.8.7.2 Date/Time Stamp

   Property Name: DTSTAMP

   Purpose: The property indicates the date/time that the instance of
   the iCalendar object was created.

   Value Type: DATE-TIME

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MUST be included in the "VEVENT", "VTODO",
   "VJOURNAL" and "VFREEBUSY" calendar components.

   Description: The value must be specified in the UTC time format.

   This property is also useful to protocols such as [IMIP] that have
   inherent latency issues with the delivery of content. This property
   will assist in the proper sequencing of messages containing iCalendar
   objects.

   This property is different than the "CREATED" and "LAST-MODIFIED"
   properties. These two properties are used to specify when the
   calendar service information was created and last modified. This is
   different than when the iCalendar object representation of the
   calendar service information was created or last modified.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     dtstamp    = "DTSTAMP" stmparam ":" [WSP] date-time CRLF

Dawson/Stenerson                  106             Expires November 1998
     stmparam   = *(";" xparam)

   Example:

     DTSTAMP:19971210T080000Z

4.8.7.3 Last Modified

   Property Name: LAST-MODIFIED

   Purpose: The property specifies the date and time that the
   information associated with the calendar component was last revised. revised
   in the calendar store.

        Note: This is analogous to the modification date and time for a
        file in the file system.

   Value Type: DATE-TIME

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: This property MAY can be specified in the "EVENT", "VTODO",
   "VJOURNAL" or "VFREEBUSY" and "VTIMEZONE" calendar components.

Dawson/Stenerson                   97            Expires September 1998

   Description: The property value MUST be specified in the UTC time
   format.

   No property parameters MAY be specified on this property.

   Format Definition: The property is defined by the following notation:

     last-mod   = "LAST-MODIFIED" lstparam ":" [WSP] date-time CRLF

     lstparam   = *(";" xparam)

   Example: The following is are examples of this property:

     LAST-MODIFIED:19960817T133000Z

4.8.7.4 Sequence Number

   Property Name: SEQUENCE

   Purpose: This property defines the revision sequence number of the
   calendar component used in within a request. sequence of revisions.

   Value Type: INTEGER integer

   Property Parameters: Non-standard property parameters can be
   specified on this property.

   Conformance: The property MAY only can be specified in a "VEVENT", "VTODO",
   "VJOURNAL" or "VFREEBUSY" calendar component.

   Description: This property is needed to properly handle the receipt
   and processing of

Dawson/Stenerson                  107             Expires November 1998
   Description: When a sequence of calendar components that have been
   delivered out of order. Such is the case for store-and-forward based
   transports. The first request component is created with a created, its sequence
   number of
   "0" (ASCII is zero (US-ASCII decimal 48). It is monotonically incremented
   by the "Organizer's" CUA each time the ORGANIZER or
   OWNER issues "Organizer" makes a
   significant revision to the request. The sequence number MUST be
   monotonically incremented when calendar component. When the "Organizer"
   makes changes to one of the following properties in a
   calendar component is changed: properties, the sequence number
   MUST be incremented:

     .  "DTSTART"

     .  "DTEND"

     .  "DUE"

     .  "RDATE"

     .  "RRULE"

     .  "EXDATE"

     .  "EXRULE"

   No

     .  "STATUS"

   In addition, changes made by the "Organizer" to other properties can
   also force the sequence number to be incremented. The "Organizer" CUA
   MUST increment the sequence number when ever it makes changes to
   properties in the calendar component that the "Organizer" deems will
   jeopardize the validity of the participation status of the
   "Attendees". For example, changing the location of a meeting from one
   locale to another distant locale could effectively impact the
   participation status of the "Attendees".

   The "Organizer" includes this property in an iCalendar object that it
   sends to an "Attendee" to specify the current version of the calendar
   component.

   The "Attendee" includes this property in an iCalendar object that it
   sends to the "Organizer" to specify the version of the calendar
   component that the "Attendee" is referring to.

   A change to the sequence number is not the mechanism that an
   "Organizer" uses to request a response from the "Attendees". The
   "RSVP" parameter MAY be specified on this property. the "ATTENDEE" property is used by the
   "Organizer" to indicate that a response from the "Attendees" is
   requested.

   Format Definition: The This property is defined by the following
   notation:

     seq = "SEQUENCE" seqparam ":" [WSP] integer CRLF
     ;Default
     ; Default is "0". "0"

     seqparam   = *(";" xparam)

Dawson/Stenerson                  108             Expires November 1998
   Example: The following is an example of this property:

     SEQUENCE:1

Dawson/Stenerson                   98            Expires September 1998 property for a calendar
   component that was just created by the "Organizer".

     SEQUENCE:0

   The following is an example of this property for a calendar component
   that has been revised two different times by the "Organizer".

     SEQUENCE:2

4.8.8   Miscellaneous Component Properties

   The following properties specify information about a number of
   miscellaneous features of calendar components.

4.8.8.1 Non-standard Properties

   Property Name: Any property name with a "X-" prefix

   Purpose: This class of property provides a framework for defining
   non-standard properties.

   Value Type: TEXT

   Property Parameters: Non-standard and language property parameters
   can be specified on this property.

   Conformance: This property MAY can be specified in any calendar
   component.

   Description: The MIME Calendaring and Scheduling Content Type
   provides a "standard mechanism for doing non-standard things". This
   extension support is provided for implementers to "push the envelope"
   on the existing version of the memo. Extension properties are
   specified by property and/or property parameter names that have the
   prefix text of "X-" (the two character sequence: LATIN CAPITAL LETTER
   X character followed by the HYPEN-MINUS character). It is recommended
   that vendors concatenate onto this sentinel another short prefix text
   to identify the vendor. This will facilitate readability of the
   extensions and minimize possible collision of names between different
   vendors. User agents that support this content type are expected to
   be able to parse the extension properties and property parameters but
   MAY
   can ignore them.

   At present, there is no registration authority for names of extension
   properties and property parameters. The data type for this property
   is TEXT. Optionally, the data type MAY can be any of the other valid data
   types.

   Any of the general property parameters MAY be specified on this
   property.

   Format Definition: The property is defined by the following notation:

     extension

     x-prop     = "X-" [vendorid] "-" text x-name *(";" [WSP] param) xparam) [";" languageparam] ":"
                  [WSP] value-list text CRLF
        ; Lines longer than 75 characters octets should be folded

     vendorid   = 3*char        ;Vendor identification prefix text

Dawson/Stenerson                  109             Expires November 1998
   Example: The following might be the ABC vendor's extension for an
   audio-clip form of subject property:

     X-ABC-MMSUBJ;TYPE=wave; VALUE=URI: http://load.noise.org/mysubj.wav

Dawson/Stenerson                   99            Expires September 1998

     X-ABC-MMSUBJ;X-ABC-MMSUBJTYPE=wave:http://load.noise.org/mysubj.wav

4.8.8.2 Request Status

   Property Name: REQUEST-STATUS

   Purpose: This property defines the status code returned for a
   scheduling request.

   Value Type: TEXT

   Property Parameters: Non-standard and language property parameters
   can be specified on this property.

   Conformance: The property MAY can be specified in a "VEVENT", "VTODO",
   "VJOURNAL" or and "VFREEBUSY" calendar component.

   Description: This property is used to return status code information
   related to the processing of an associated iCalendar object. The data
   type for this property is TEXT.

   The value consists of a short return status, a longer return status
   description, and optionally the offending data. The components of the
   value are separated by the SEMICOLON character (ASCII (US-ASCII decimal 59).

   The short return status is a PERIOD character (ASCII (US-ASCII decimal 46)
   separated 3-tuple of integers. For example, "3.1.1". The successive
   levels of integers provide for a successive level of status code
   granularity.

   The following are initial classes for the return status code.
   Individual iCalendar object methods will define specific return
   status codes for these classes. In addition, other classes for the
   return status code may be defined using the registration process
   defined later in this memo.

     |==============+===============================================|
     | Short Return | Longer Return Status Description              |
     | Status Code  |                                               |
     |==============+===============================================|
     |    1.xx      | Preliminary success. This class of status     |
     |              | of status code indicates that the request has |
     |              | request has been initially processed but that |
     |              | completion is pending.                        |
     |==============+===============================================|
     |    2.xx      | Successful. This class of status code         |
     |              | indicates that the request was completed      |
     |              | successfuly. However, the exact status code   |
     |              | MAY can indicate that a fallback has been taken.  |
     |==============+===============================================|
     |    3.xx      | Client Error. This class of status code       |

Dawson/Stenerson                  110             Expires November 1998
     |              | indicates that the request was not successful.|
     |              | The error is the result of either a syntax or |
     |              | a semantic error in the client formatted      |
     |              | request. Request should not be retried until  |
     |              | the condition in the request is corrected.    |
     |==============+===============================================|
     |    4.xx      | Scheduling Error. This class of status code   |
     |              | indicates that the request was not successful.|

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     |              | Some sort of error occurred within the        |
     |              | calendaring and scheduling service, not       |
     |              | directly related to the request itself.       |
     |==============+===============================================|

   Only the "LANGUAGE" property parameter MAY be specified on this
   property.

   Format Definition: The property is defined by the following notation:

     rstatus    = "REQUEST-STATUS" [rstatparam] rstatparam ":" [WSP]
                  statcode ";" [WSP] statdesc [";" [WSP] extdata]

     rstatparam = ";" [WSP] languageparm [";" languageparm]
                  *(";" xparam)

     statcode   = 1*DIGIT *("." 1*DIGIT)
     ;Hierarchical, numeric return status code

     statdesc   = text
     ;Textual status description

     extdata    = text
     ;Textual exception data. For example, the offending property
     ;name and value or complete property line.

   Example: The following are some possible examples of this property
   (Note: property.
   The BACKSLASH character escapement of COMMA and SEMICOLON separator characters in the property value
   are BACKSLASH character escaped because it has they appear in a  text value type): value.

     REQUEST-STATUS:2.0;Success

     REQUEST-STATUS:3.1;Invalid property value;DTSTART:96-Apr-01

     REQUEST-STATUS:2.8; Success\, repeating event ignored. Scheduled
      as a single event.;RRULE:FREQ=WEEKLY\;INTERVAL=2

     REQUEST-STATUS:4.1;Event conflict. Date/time is busy.

     REQUEST-STATUS:3.7;Invalid calendar user;ATTENDEE:
      MAILTO:jsmith@host.com

5  iCalendar Object Examples

   The following examples are provided as an informational source of
   illustrative iCalendar objects consistent with this content type.

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   The following example specifies a three day three-day conference that begins at
   8:00 AM EDT, September 18, 1996 and end at 6:00 PM EDT, September 20,
   1996.

     BEGIN:VCALENDAR
     PRODID:-//xyz Corp//NONSGML PDA Calendar Verson 1.0//EN
     VERSION:2.0
     BEGIN:VEVENT

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     DTSTAMP:19960704T120000Z
     UID:uid1@host.com
     ORGANIZER:MAILTO:jsmith@host.com
     DTSTART:19960918T143000Z
     DTEND:19960920T220000Z
     STATUS:CONFIRMED
     CATEGORIES:CONFERENCE
     SUMMARY:Networld+Interop Conference
     DESCRIPTION:Networld+Interop Conference
       and Exhibit\nAtlanta World Congress Center\n
      Atlanta, Georgia
     END:VEVENT
     END:VCALENDAR

   The following example specifies a group scheduled meeting that begin
   at 8:30 AM EST on March 12, 1998 and end at 9:30 AM EST on March 12,
   1998. The "Organizer" has scheduled the meeting with one or more
   calendar users in a group. A time zone specification for Eastern
   United States has been specified.

     BEGIN:VCALENDAR
     PRODID:-//RDU Software//NONSGML HandCal//EN
     VERSION:2.0
     BEGIN:VTIMEZONE
     TZID:Eastern US
     BEGIN:STANDARD
     DTSTART:19981025T020000
     RDATE:19981025T020000
     TZOFFSETFROM:-0400
     TZOFFSETTO:-0500
     TZNAME:EST
     END:STANDARD
     BEGIN:DAYLIGHT
     DTSTART:19990404T020000
     RRULE:19990404T020000
     RDATE:19990404T020000
     TZOFFSETFROM:-0500
     TZOFFSETTO:-0400
     TZNAME:EDT
     END:DAYLIGHT
     END:VTIMEZONE
     BEGIN:VEVENT
     DTSTAMP:19980309T231000Z
     UID:guid-1.host1.com
     ORGANIZER;ROLE=CHAIR:mrbig@host.com
     ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT;TYPE=GROUP:
     ORGANIZER;ROLE=CHAIR:MAILTO:mrbig@host.com
     ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT;CUTYPE=GROUP:
      MAILTO:employee-A@host.com

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     DESCRIPTION:Project XYZ Review Meeting
     CATEGORIES:MEETING
     CLASS:PUBLIC
     CREATED:19980309T130000Z
     SUMMARY:XYZ Project Review
     DTSTART;TZID=EST:19980312T083000
     DTEND;TZID=EST:19980312T0930
     DTSTART;TZID=US-Eastern:19980312T083000
     DTEND;TZID=US-Eastern:19980312T093000
     LOCATION:1CP Conference Room 4350

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      END:VEVENT
     END:VCALENDAR

   The following is an example of an iCalendar object passed in a MIME
   message with a single body part consisting of a "text/calendar"
   Content Type.

     TO:jsmith@host1.com
     FROM:jdoe@host1.com
     MIME-VERSION:1.0
     MESSAGE-ID:<id3@host1.com>
     CONTENT-TYPE:text/calendar

     BEGIN:VCALENDAR
     METHOD:xyz
     VERSION:2.0
     PRODID:-//ABC Corporation//NONSGML My Product//EN
     BEGIN:VEVENT
     DTSTAMP:19970324T1200Z
     SEQUENCE:0
     UID:uid3@host1.com
     ORGANIZER:jdoe@host1.com
     ORGANIZER:MAILTO:jdoe@host1.com
     ATTENDEE;RSVP=TRUE:MAILTO:jsmith@host1.com
     DTSTART:19970324T123000Z
     DTEND:19970324T210000Z
     CATEGORIES:MEETING,PROJECT
     CLASS:PUBLIC
     SUMMARY:Calendaring Interoperability Planning Meeting
     DESCRIPTION:Discuss how we can test c&s interoperability\n
      using iCalendar and other IETF standards.
     LOCATION:LDB Lobby
     ATTACH:file:///xyzCorp.com/conf/bkgrnd.ps
     END:VEVENT
     END:VCALENDAR

   The following is an example of a to-do due on April 15, 1998. An
   audio alarm has been specified to remind the calendar user at noon,
   the day before the to-do is expected to be completed and repeat
   hourly, four additional times. The to-do definition has been modified
   twice since it was initially created.

     BEGIN:VCALENDAR
     VERSION:2.0
     PRODID:-//ABC Corporation//NONSGML My Product//EN
     BEGIN:VTODO
     DTSTAMP:19980130T134500Z

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     SEQUENCE:2
     UID:uid4@host1.com
     ORGANIZER:unclesam@us.gov
     ATTENDEE;ATTSTAT=ACCEPTED;ATTSTAT=ACCEPTED:MAILTO:jqpublic@host.com
     ORGANIZER:MAILTO:unclesam@us.gov
     ATTENDEE;PARTSTAT=ACCEPTED:MAILTO:jqpublic@host.com
     DUE:19980415T235959
     STATUS:NEEDS-ACTION
     SUMMARY:Submit Income Taxes
     BEGIN:VALARM

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     ALARM-TYPE:AUDIO
     ACTION:AUDIO
     TRIGGER:19980403T120000
     ATTACH:http://host.com/pub/audio-files/ssbanner.wav
     REPEAT:4
     DURATION:PT1H
     END:VALARM
     END:VTODO
     END:VCALENDAR

   The following is an example of a journal entry.

     BEGIN:VCALENDAR
     VERSION:2.0
     PRODID:-//ABC Corporation//NONSGML My Product//EN
     BEGIN:VJOURNAL
     DTSTAMP:19970324T120000Z
     UID:uid5@host1.com
     ORGANIZER:MAILTO:jsmith@host.com
     STATUS:DRAFT
     CLASS:PUBLIC
     CATEGORY:Project Report, XYZ, Weekly Meeting
     DESCRIPTION:Project xyz Review Meeting Minutes\n
      Agenda\n1. Review of project version 1.0 requirements.\n2.
     Definition
      of project processes.\n3. Review of project schedule.\n
      Participants: John Smith, Jane Doe, Jim Dandy\n-It was
       decided that the requirements need to be signed off by
       product marketing.\n-Project processes were accepted.\n
      -Project schedule needs to account for scheduled holidays
       and employee vacation time. Check with HR for specific
       dates.\n-New schedule will be distributed by Friday.\n-
      Next weeks meeting is cancelled. No meeting until 3/23.
     END:VJOURNAL
     END:VCALENDAR

   The following is an example of published busy time information. The
   iCalendar object might be placed in the network resource
   www.host.com/calendar/busytime/jsmith.ifb.

     BEGIN:VCALENDAR
     VERSION:2.0
     PRODID:-//RDU Software//NONSGML HandCal//EN
     BEGIN:VFREEBUSY
     ATTENDEE:jsmith@host.com
     ORGANIZER:MAILTO:jsmith@host.com
     DTSTART:19980313T141711Z
     DTEND:19980410T141711Z

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     FREEBUSY:19980314T233000Z/19980315T003000Z
     FREEBUSY:19980316T153000Z/19980316T163000Z
     FREEBUSY:19980318T030000Z/19980318T040000Z
     URL:http://www.host.com/calendar/busytime/jsmith.ifb
     END:VFREEBUSY
     END:VCALENDAR

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6  Recommended Practices

   These recommended practices should be followed in order to assure
   consistent handling of the following cases for an iCalendar object.

   1.      Content lines longer than 75 character octets SHOULD be folded.

   2.      A calendar entry with a "DTSTART" property but no "DTEND" property
     - The event does not take up any time. It is intended to represent
     an event that is associated with a given calendar date and time of
     day, such as an anniversary. Since the event does not take up any
     time, it MUST NOT be used to record busy time no matter what the
     value for the "TRANSP" property.

   3.      When the "DTSTART" and "DTEND", for "VEVENT", "VJOURNAL" and
     "VFREEBUSY" calendar components, and "DTSTART" and "DUE", for
     "VTODO" calendar components, have the same value data type (e.g.,
     DATE-TIME), they should SHOULD specify values in the same time format
     (e.g., UTC time format).

   4.      A combination of "RRULE" and "RDATE" properties that produces more
     than one instance for a given date/time - Only one recurrence can
     occur on a given date/time interval. Just one instance for the
     date/time is recorded.

   5.      A particular iCalendar object method that specifies "ATTENDEE"
     properties with the "MEMBER" property parameter, for which the
     recipient has multiple memberships - Recipient should reply to
     only the first "MEMBER" property parameter value that it can
     match.

   6.      An implementation MAY can truncate a "SUMMARY" property value to 255
     characters.

   7.      If seconds of the minute are not supported by an implementation,
     then a value of "00" should be specified for the seconds component the seconds component
     in a time value.

   8.      If the value type parameter (VALUE=) contains an unknown value
     type, it should be treated as TEXT.

   9.      TZURL values SHOULD NOT be specified as a FILE URI type. This URI
     form can be useful within an organization, but is problematic in
     the Internet.

   10.       Some possible English values for CATEGORIES property include
     "ANNIVERSARY", "APPOINTMENT", "BUSINESS", "EDUCATION", "HOLIDAY",

Dawson/Stenerson                  115             Expires November 1998
     "MEETING", "MISCELLANEOUS", "NON-WORKING HOURS", "NOT IN OFFICE",
     "PERSONAL", "PHONE CALL", "SICK DAY", "SPECIAL OCCASION",
     "TRAVEL", "VACATION". Categories can be specified in any
     registered language.

   11.       Some possible English values for RESOURCES property include
     "CATERING", "CHAIRS", "COMPUTER PROJECTOR", "EASEL", "OVERHEAD
     PROJECTOR", "SPEAKER PHONE", "TABLE", "TV", "VCR", "VIDEO PHONE",
     "VEHICLE". Resources can be specified in a time value. any registered language.

7  Registration of Content Type Elements

   This section provide the process for registration of MIME Calendaring
   and Scheduling Content Type iCalendar object methods and new or
   modified properties.

7.1 Registration of New and Modified iCalendar Object Methods

   New MIME Calendaring and Scheduling Content Type iCalendar object
   methods are registered by the publication of an IETF Request for
   Comment (RFC). Changes to an iCalendar object method are registered
   by the publication of a revision of the RFC defining the method.

Dawson/Stenerson                  105            Expires September 1998

7.2 Registration of New Properties

   This section defines procedures by which new properties or enumerated
   property values for the MIME Calendaring and Scheduling Content Type
   can be registered with the IANA. Note that non-IANA Non-IANA properties MAY can be used by
   bilateral agreement, provided the associated properties names follow
   the "X-" convention.

   The procedures defined here are designed to allow public comment and
   review of new properties, while posing only a small impediment to the
   definition of new properties.

   Registration of a new property is accomplished by the following
   steps.

7.2.1   Define the property

   A property is defined by completing the following template.

     To: ietf-calendar@imc.org

     Subject: Registration of text/calendar MIME property XXX

     Property name:

     Property purpose:

     Property data value type(s):

     Property encoding:

     Property special notes (optional):

     Intended usage: (one of COMMON, LIMITED USE or OBSOLETE) parameter (s):

Dawson/Stenerson                  116             Expires November 1998
     Conformance:

     Description:

     Format definition:

     Examples:

   The meaning of each field in the template is as follows.

   Property name: The name of the property, as it will appear in the
   body of an text/calendar MIME Content-Type "property: value" line to
   the left of the colon ":".

   Property purpose: The purpose of the property (e.g., to indicate a
   delegate for the event or to-do, etc.). Give a short but clear
   description.

   Property data type(s): value type (s): Any of the valid data value types for the
   property value needs to be specified. The default data value type also
   needs to be specified. If a new data value type is specified, it needs to
   be declared in this section.

   Property special notes: parameter (s): Any of the valid property parameters for the
   property needs to be specified.

   Conformance: The calendar components that the property can appear in
   needs to be specified.

   Description: Any special notes about the property, how it is to be
   used, etc.

Dawson/Stenerson                  106            Expires September 1998

   Format definition: The ABNF for the property definition needs to be
   specified.

   Examples: One or more examples of instances of the property needs to
   be specified.

7.2.2   Post the Property definition

   The property description MUST be posted to the new property
   discussion list, ietf-calendar@imc.org.

7.2.3   Allow a comment period

   Discussion on the new property MUST be allowed to take place on the
   list for a minimum of two weeks. Consensus MUST be reached on the
   property before proceeding to the next step.

7.2.4   Submit the property for approval

   Once the two-week comment period has elapsed, and the proposer is
   convinced consensus has been reached on the property, the
   registration application should be submitted to the Method Reviewer

Dawson/Stenerson                  117             Expires November 1998
   for approval. The Method Reviewer is appointed to the Application
   Area Directors and MAY can either accept or reject the property
   registration. An accepted registration should be passed on by the
   Method Reviewer to the IANA for inclusion in the official IANA method
   registry. The registration MAY can be rejected for any of the following
   reasons. 1) Insufficient comment period; 2) Consensus not reached; 3)
   Technical deficiencies raised on the list or elsewhere have not been
   addressed. The Method Reviewer's decision to reject a property MAY can be
   appealed by the proposer to the IESG, or the objections raised can be
   addressed by the proposer and the property resubmitted.

7.3 Property Change Control

   Existing properties MAY can be changed using the same process by which
   they were registered.

        1.           Define the change

        2.           Post the change

        3.           Allow a comment period

        4.           Submit the property for approval

   Note that the original author or any other interested party MAY can
   propose a change to an existing property, but that such changes
   should only be proposed when there are serious omissions or errors in
   the published memo. The Method Reviewer MAY can object to a change if it
   is not backwards backward compatible, but is not required to do so.

   Property definitions can never be deleted from the IANA registry, but
   properties which are no longer believed to be useful can be declared
   OBSOLETE by a change to their "intended use" field.

8  References

   The following document documents are referred to within this memo.

Dawson/Stenerson                  107            Expires September 1998

   [ICMS] "Internet Calendaring Model Specification", Internet-Draft,
   July
   October 1997, ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-mod-
   03.txt. ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-
   mod-03.txt.

   [IMIP] "iCalendar Message-based Interoperability Protocol (IMIP)",
   Internet Draft, February April 1998, http://www.imc.org/draft-ietf-calsch-
   imip-05.txt.

   [ITIP] "iCalendar Transport-Independent Interoperability Protocol
   (iTIP) : Scheduling Events, Busy Time, To-dos and Journal Entries ",
   Internet-Draft, April 1998, http://www.imc.org/draft-ietf-calsch-
   imip-04.txt.
   itip-05.txt.

   [ISO 8601] ISO 8601, "Data elements and interchange formats_
   Information interchange--Representation of dates and times",
   International Organization for Standardization, June, 1988. This

Dawson/Stenerson                  118             Expires November 1998
   standard is also addressed by the Internet Draft document
   ftp://ds.internic.net/internet-drafts/draft-newman-datetime-00.txt.

   [ISO 9070] ISO/IEC 9070, "Information Technology_SGML Support
   Facilities--Registration Procedures for Public Text Owner
   Identifiers", Second Edition, International Organization for
   Standardization, April, April 1991.

   [ITIP] "iCalendar Transport-Independent Interoperability Protocol
   (iTIP) : Scheduling Events, Busy Time, To-dos and Journal Entries ",
   Internet-Draft, February 1998, http://www.imc.org/draft-ietf-calsch-
   itip-03.txt.

   [MIME DIR] Howes, T., Smith, M., "A MIME Content-Type for Directory
   Information", Internet-draft-ietf-asid-mime-direct-07.txt, November, November
   1997.

   [RFC 822] Crocker, D., "Standard for the Format of ARPA Internet Text
   Messages", STD 11, RFC 822, August 1982.

   [RFC 1738] Berners-Lee, T., Masinter, L., McCahill, M., "Uniform
   Resource Locators (URL)", RFC 1738, December 1994.

   [RFC 1766] Alvestrand, H., "Tags for the Identification of
   Languages", March 1995.

   [RFC 1872] Levinson, E., "The MIME Multipart/Related Content-type,"
   RFC 1872, December 1995.

   [RFC 1983] "Internet Users' Glossary", RFC 1983, August 1996.

   [RFC 2045] Freed, N., Borenstein, N., " Multipurpose Internet Mail
   Extensions (MIME) - Part One: Format of Internet Message Bodies", RFC
   2045, November 1996.

   [RFC 2046] Freed, N., Borenstein, N., " Multipurpose Internet Mail
   Extensions (MIME) - Part Two: Media Types", RFC 2046, November 1996.

   [RFC 2047] Moore, K., "Multipurpose Internet Mail Extensions (MIME) -
   Part Three: Message Header Extensions for Non-ASCII Text", RFC 2047,
   November 1996.

Dawson/Stenerson                  108            Expires September 1998

   [RFC 2048] Freed, N., J. Klensin, J. Postel, "Multipurpose Internet
   Mail Extensions (MIME) - Part Four: Registration Procedures", RFC
   2048, January 1997.

   [RFC 2111] "Content-ID and Message-ID Uniform Resource Locators", RFC
   2111, March 1997.

   [RFC 2119] "Key words for use in RFCs to Indicate Requirement
   Levels", RFC 2119, March 1997.

   [UTF-8]

   [RFC 2234] Crocker, D., Overell, P., "Augmented BNF for Syntax
   Specifications: ABNF", RFC 2234, November 1997.

   [RFC 2279] "UTF-8, a transformation format of Unicode and ISO
   10646",Internet-Draft, July,1996, ftp://ftp.ietf.org/internet-
   drafts/draft-yergeau-utf8-01.txt. 10646", RFC 2279,
   January 1998.

   [VCARD] Internet Mail Consortium, "vCard - The Electronic Business
   Card Version 2.1",  http://www.imc.org/pdi/vcard-21.txt, September
   18, 1996.

Dawson/Stenerson                  119             Expires November 1998
   [VCAL] Internet Mail Consortium, "vCalendar - The Electronic
   Calendaring and Scheduling Exchange Format",
   http://www.imc.org/pdi/vcal-10.txt, September 18, 1996.

   [XAPIA] "XAPIA CSA, Calendaring and Scheduling Application
   Programming Interface (CSA) Version 1.0", X.400 API Association,
   November 15, 1994.

9  Acknowledgments

   A hearty thanks to the IETF Calendaring and Scheduling Working Group
   and also the following individuals who have participated in the
   drafting, review and discussion of this memo:

   Roland Alden, Harald T. Alvestrand, Eric Berman, Denis Bigorgne, John
   Binici, Bill Bliss, Philippe Boucher, Steve Carter, Andre
   Courtemanche, Dave Crocker, David Curley, Alec Dun, John Evans, Ross
   Finlayson, Randell Flint, Ned Freed, Patrik Falstrom, Chuck
   Grandgent, Mark Handley, Steve Hanna, Paul B. Hill, Paul Hoffman,
   Ross Hopson, Mark Horton, Daryl Huff, Bruce Kahn, C. Harald Koch,
   Ryan Jansen, Don Lavange, Antoine Leca, Theodore Lorek, Steve
   Mansour, Skip Montanaro, Keith Moore, Cecil Murray, Chris Newman,
   John Noerenberg, Ralph Patterson, Pete Resnick, Keith Rhodes, Robert
   Ripberger, John Rose, Doug Royer, Andras Salamar, Ted Schuh, Vinod
   Seraphin, Derrick Shadel, Ken Shan, Andrew Shuman, Steve Silverberg,
   William P. Spencer, John Sun, Mark Towfiq, Yvonne Tso, Robert Visnov,
   James L. Weiner, Mike Weston, William Wyatt.

10 Author's Address

   The following address information is provided in a MIME-VCARD,
   Electronic Business Card, format.

   The authors of this draft are:

Dawson/Stenerson                  109            Expires September 1998

     BEGIN:VCARD
     VERSION:2.1
     FN:Frank Dawson
     ORG:Lotus Development Corporation
     ADR;WORK;POSTAL;PARCEL:;6544 Battleford Drive;
      Raleigh;NC;27613-3502;USA
     TEL;WORK;MSG:+1-919-676-9515
     TEL;WORK;FAX:+1-919-676-9564
     EMAIL;INTERNET;PREF:Frank_Dawson@Lotus.com
     EMAIL;INTERNET:fdawson@earthlink.net
     URL:http://home.earthlink.net/~fdawson
     END:VCARD

     BEGIN:VCARD
     VERSION:2.1
     FN:Derik Stenerson
     ORG:Microsoft Corporation
     ADR;WORK;POSTAL;PARCEL:;One Microsoft Way;
      Redmond;WA;98052-6399;USA

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     TEL;WORK;MSG:+1-425-936-5522
     TEL;WORK;FAX:+1-425-936-7329
     EMAIL;INTERNET:deriks@Microsoft.com
     END:VCARD

   The iCalendar object is a result of the work of the Internet
   Engineering Task Force Calendaring and Scheduling Working Group. The
   chairman of that working group is:

     BEGIN:VCARD
     VERSION:2.1
     FN:Anik Ganguly
     ORG:OnTime, Inc.
     ADR;WORK;POSTAL;PARCEL:10 Floor;21700 Northwestern Highway;
      Southfield;MI;48075;USA
     TEL;WORK;MSG:+1-248-559-5955
     TEL;WORK;FAX:+1-248-559-5034
     EMAIL;INTERNET:anik@ontime.com
     END:VCARD

11 Full Copyright Statement

   "Copyright (C) The Internet Society (date).  All Rights Reserved.

   This document and translations of it MAY may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implmentation MAY may be prepared, copied, published and
   distributed, in whole or in part, without restriction of any kind,
   provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself MAY may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process MUST be

Dawson/Stenerson                  110            Expires September 1998
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Dawson/Stenerson                  111                  121             Expires September November 1998