Network Working Group                               Frank Dawson, Lotus
Internet Draft                               Derik Stenerson, Microsoft
<draft-ietf-calsch-ical-04.txt>                        October 22,
<ietf-calsch-ical-05.txt>                             November 21, 1997
Expires Mary 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 also distribute working
   documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months. Internet-Drafts MAY 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 the current status of any Internet-Draft, please check the
   1id-abstracts.txt listing contained in the Internet-Drafts Shadow
   Directories on ds.internic.net (US East Coast), nic.nordu.net
   (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific
   Rim).

   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 a 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''. 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 and to-do 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
   or using HTTP. In addition, the content type is useful as an object

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   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. This memo is based on the
   calendaring and scheduling model defined in []. The document is also
   the basis for the calendaring and scheduling interoperability
   protocol defined in [ITIP].

   This memo also includes the format for defining 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.

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   Table of Contents

1.Introduction........................................................8
2.Basic

1. Introduction........................................................5
2. Basic Grammar and Conventions.......................................8 Conventions.......................................5
 2.1 Formatting Conventions...........................................9 Conventions ...........................................6
 2.2 Related Memos...................................................10
3.TEXT/CALENDAR Memos ....................................................7
3. TEXT/CALENDAR Registration Information.............................10
4.iCalendar Information..............................7
4. iCalendar Object Specification.....................................12 Specification......................................9
 4.1 Content Considerations..........................................13
  4.1.1Content Lines................................................13
  4.1.2List Considerations ...........................................9
  4.1.1 Content Lines ................................................10
  4.1.2 List and Field Separators....................................14
  4.1.3Multiple Values..............................................15
  4.1.4Binary Content...............................................15
  4.1.5Property Parameters..........................................15
  4.1.6Alternate Separators ....................................12
  4.1.3 Multiple Values ..............................................13
  4.1.4 Binary Content ...............................................13
  4.1.5 Property Parameters ..........................................13
  4.1.6 Alternate Text Representation................................16
  4.1.7Character Set................................................17
  4.1.8Language.....................................................17
  4.1.9Value Representation ................................14
  4.1.7 Character Set ................................................14
  4.1.8 Inline Encoding ..............................................15
  4.1.9 Language .....................................................15
  4.1.10 Value Data Types.............................................17 Types ............................................15
 4.2 iCalendar object................................................28 object ................................................25
 4.3 Property........................................................28 Property ........................................................26
 4.4 Calendar Components.............................................29
  4.4.1Event Component..............................................29
  4.4.2To-do Component..............................................31
  4.4.3Journal Component............................................31
  4.4.4Free/Busy Component..........................................32
  4.4.5Alarm Component..............................................33
  4.4.6Timezone Component...........................................34 Components .............................................26
  4.4.1 Event Component ..............................................26
  4.4.2 To-do Component ..............................................28
  4.4.3 Journal Component ............................................29
  4.4.4 Free/Busy Component ..........................................30
  4.4.5 Alarm Component ..............................................31
  4.4.6 Timezone Component ...........................................33
 4.5 Calendar Properties.............................................38
  4.5.1Calendar Scale...............................................38
  4.5.2Method.......................................................39
  4.5.3Product Identifier...........................................39
  4.5.4Source.......................................................40
  4.5.5Source Name..................................................40
  4.5.6Version......................................................41 Properties .............................................37
  4.5.1 Calendar Scale ...............................................37
  4.5.2 Method .......................................................37
  4.5.3 Product Identifier ...........................................38
  4.5.4 Source .......................................................38
  4.5.5 Source Name ..................................................39
  4.5.6 Version ......................................................39
 4.6 Component Properties............................................41
  4.6.1Attachment...................................................41
  4.6.2Attendee.....................................................42
  4.6.3Categories...................................................44
  4.6.4Classification...............................................45
  4.6.5Comment......................................................46
  4.6.6Contact......................................................46
  4.6.7Date/Time Completed..........................................47
  4.6.8Date/Time Created............................................47
  4.6.9Date/Time Due................................................47
  4.6.10..................................................Date/Time Properties ............................................40
  4.6.1 Attachment ...................................................40
  4.6.2 Attendee .....................................................40
  4.6.3 Categories ...................................................43
  4.6.4 Classification ...............................................44
  4.6.5 Comment ......................................................44
  4.6.6 Contact ......................................................45
  4.6.7 Date/Time Completed ..........................................45
  4.6.8 Date/Time Created ............................................46
  4.6.9 Date/Time Due ................................................46
  4.6.10 Date/Time End        48
  4.6.11................................................Date/Time ...............................................46
  4.6.11 Date/Time Stamp        48
  4.6.12................................................Date/Time .............................................47
  4.6.12 Date/Time Start        49
  4.6.13.......................................................Daylight        49
  4.6.14....................................................Description        50
  4.6.15.......................................................Duration        50
  4.6.16...........................................Exception .............................................47
  4.6.13 Daylight ....................................................48
  4.6.14 Description .................................................48
  4.6.15 Duration ....................................................49
  4.6.16 Exception Date/Times        51
  4.6.17.................................................Exception ........................................50
  4.6.17 Exception Rule        52
  4.6.18.................................................Free/Busy Time        52 ..............................................50

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  4.6.19............................................Geographic
  4.6.18 Free/Busy Time ..............................................51
  4.6.19 Geographic Position        54
  4.6.20..................................................Last .........................................52
  4.6.20 Last Modified        54
  4.6.21.......................................................Location        54
  4.6.22...............................................Percent ...............................................53
  4.6.21 Location ....................................................53
  4.6.22 Percent Complete        55
  4.6.23.......................................................Priority        56
  4.6.24..........................................Recurrence ............................................54
  4.6.23 Priority ....................................................54
  4.6.24 Recurrence Date/Times        56
  4.6.25..................................................Recurrence .......................................55
  4.6.25 Recurrence ID        57
  4.6.26................................................Recurrence ...............................................56
  4.6.26 Recurrence Rule        58
  4.6.27.....................................................Related .............................................57
  4.6.27 Related To        65
  4.6.28...................................................Repeat ..................................................64
  4.6.28 Repeat Count        66
  4.6.29.................................................Request ................................................65
  4.6.29 Request Status        66
  4.6.30......................................................Resources        68
  4.6.31................................................Sequence ..............................................66
  4.6.30 Resources ...................................................67
  4.6.31 Sequence Number        68
  4.6.32.........................................................Status        69
  4.6.33........................................................Summary        70
  4.6.34..............................................Time .............................................68
  4.6.32 Status ......................................................68
  4.6.33 Summary .....................................................69
  4.6.34 Time Transparency        70
  4.6.35.................................................Time ...........................................69
  4.6.35 Time Zone Name        71
  4.6.36...............................................Time ..............................................70
  4.6.36 Time Zone Offset        71
  4.6.37.......................................Uniform ............................................70
  4.6.37 Uniform Resource Locator        71
  4.6.38..............................................Unique ....................................70
  4.6.38 Unique Identifier        72
  4.6.39........................................Non-standard ...........................................71
  4.6.39 Non-standard Properties        73
5.Recommended Practices..............................................73
6.Registration .....................................72
5. Recommended Practices..............................................72
6. Registration of Content Type Elements..............................74 Elements..............................73
 6.1 Registration of New and Modified iCalendar object Methods.......74 Methods .......73
 6.2 Registration of New Properties..................................74
  6.2.1Define Properties ..................................73
  6.2.1 Define the property..........................................74
  6.2.2Post property ..........................................73
  6.2.2 Post the Property definition.................................75
  6.2.3Allow definition .................................74
  6.2.3 Allow a comment period.......................................75
  6.2.4Submit period .......................................74
  6.2.4 Submit the property for approval.............................75 approval .............................74
 6.3 Property Change Control.........................................76
7.File extension.....................................................76
8.Macintosh Control .........................................75
7. File extension.....................................................75
8. Macintosh File Type Code...........................................76
9.References.........................................................76 Code...........................................75
9. References.........................................................75
10. Acknowledgments..................................................78 Acknowledgments...................................................77
11. Copyright........................................................78
12. Author's Address.................................................78
13. Address..................................................77
12. iCalendar object Examples........................................79
14. Examples.........................................78
13. Full Copyright Statement.........................................82

1. Statement..........................................80

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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 groupware 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 or a Group Scheduling product.

   The calendaring and scheduling model implemented by this memo is
   defined in the [ICMS].

   The 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 definition of a calendaring and scheduling interoperability
   protocol is the subject of another memo [ITIP].

   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.

   The memo also includes a formal grammar for the content type to aid
   in 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", "MAY" and "OPTIONAL" in this
   document are to be interopreted interoperated as described in [RFC 2119].

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

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   The notation used in this memo is the augmented BNF notation of [RFC
   822]. 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. 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 that
        is not essential to the building of a conformant implementation
        of the specifications of this memo. The information is provided
        to highlight a particular feature or characteristic of the
        specifications.

   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. In order
   to refer to elements of the calendaring and scheduling model, model [ICMS],
   core object (this memo) or interoperability protocol defined [ITIP] in this memo, [ICMS] and
   [ITIP],
   memo 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] 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.

   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, quoted-strings of text,
   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

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   this memo are referred to with capitalized text, either alone or
   followed by the word "value".

2.2     Related Memos

   Implementers will need to For example, the "MINUTELY" value can

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   be familiar used with several 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;

   [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.

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.

   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

     Required parameters: method

     The "method" parameter is used to convey the iCalendar object
     method to which the calendaring and scheduling information
     pertains. It also is an identifier for the set of properties that
     the iCalendar object will consist 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

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     text/calendar content type MAY contain any set of properties

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     permitted by the Calendaring and Scheduling Core Object
     Specification.

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

     method     = <Identifier for any 1*(ALPHA / DIGIT / "-")
        ; IANA registered iCalendar object method> method

     Optional parameters: charset, component

     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.

     The "component" parameter conveys the type of iCalendar calendar
     component within the body part. If the iCalendar object contains
     more than one calendar component, then the components are specified
     as a comma-separated list of values.

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

        component       = "VEVENT" / "VTODO" / "VJOURNAL" / "VFREEBUSY"
                        / x-token x-name / iana-comp

        x-token = <The two characters "X-" or "x-" followed, with
                   no intervening white space, by any atom, where
                   atom is from section 3.3 of [RFC 822]>

        iana-comp = <A publicly defined extension component,
                     registered with IANA, as specified by this
                     document> iana-token

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

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

     Security 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 be constructed by
     someone other than the "Organizer" and sent to the "Attendees". In
     addition in this memo, an "Attendee" of a "VEVENT", "VTODO",
     "VJOURNAL" calendar component is the only person authorized to

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     update any parameter associated with their "ATTENDEE" property and
     send it to the "Organizer". An iCalendar object that maliciously
     changes the "ATTENDEE" parameters MAY be constructed by someone
     other than the real "Attendee" and sent to the "Organizer".

     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 be of type
     PROCEDURE and MAY have an attachment containing some sort of

Dawson/Stenerson                   8                   Expires MAY 1998
     executable program. Implementations that incorporate these types of
     alarms are subject to any virus or malicious attack that MAY occur
     as a result of executing the attachment.

     ATTACHMENTS - - An iCalendar object MAY include references to
     Uniform Resource Locators that MAY 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.

     Interoperability 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.

     Intended Usage: COMMON

     Published specification: This memo.

     Author/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 be used independent of such content

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   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 Considerations

   The iCalendar object consists of lines of text. This section defines
   how the content lines MUST be formatted.

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4.1.1   Content Lines

   The iCalendar object consists of individual lines of text, delimited
   by a line break, which is a CRLF sequence (ASCII decimal 13, followed
   by ASCII decimal 10). Line Lines of text should not be longer than 76
   characters, excluding the line break.

   Long lines of text can be split into a multiple line representations
   using a line "folding" technique. That is, a long line MAY be split
   at any point by inserting a CRLF immediately followed by a single
   LWSP
   linear white space character (i.e., SPACE, ASCII decimal 32 or HTAB,
   ASCII decimal 9). Any sequence of CRLF followed immediately by a
   single LWSP 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 long 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 LWSP linear white
   space character that immediately follows.

   An intentional formatted text line break MAY only be included in a
   property value by representing the line break with the character
   sequence of BACKSLASH (ASCII decimal 92), followed by a LATIN SMALL
   LETTER N (ASCII decimal 110) or a LATIN CAPITAL LETTER N (ASCII
   decimal 78), that is "\n" or "\N".

   For example a multiple line "DESCRIPTION" property value of:

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

   Could be represented as:

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     DESCRIPTION:Project_XYZ Final_Review\n
      Conference Room - 3B\nCome_Prepared.

   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 as defined by the following notation:

     contentline = name [";" [ws] paramlist] *(";" [WSP] param ) ":" [ws] value [WSP] value-list CRLF
     ;Folding permitted on content lines.
     ;Lines
        ; Lines longer than 75 characters should be less than 76 characters, excluding CRLF.

     LWSP folded

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     name       = SPACE iana-token / HTAB

     SPACE x-name

     x-name     = <ASCII Decimal 32>

     HTAB "X-" 1*(ALPHA / DIGIT / "-")
        ;Reservered for experimental use.

     param      = <ASCII Decimal 9>

     ws param-name "=" param-value *("," param-value)

     param-name = SPACE / HTAB

     name iana-token

     param-value = iana-name quoted-string / x-name    ;An iCalendar property

     iana-name text

     value-list = <One of the properties defined by this memo or
                   an IANA registered property, as defined value-struct *([FOLD] "," value-struct)
        ; permitted values are restricted by the
                   registration process in this memo.>

     x-name valuetype

     value-struct = <The two characters "X-" or "x-" followed, with no
                   intervening white space, value-elem *([FOLD] ";" value-elem)

     value-elem = folded-text / folded-b
        ; encoding determined by any atom. A non-standard
                   property name.>

     value encoding parameter

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

     text       = *SAFE-CHAR

     quoted-string = DQUOTE *(QSAFE-CHAR / date-time QUOTED-CHAR) DQUOTE

     folded-text = *([FOLD] (SAFE-CHAR / duration ":" / float DQUOTE / integer ESCAPED-CHAR))

     folded-base64 = *([FOLD] 4B-CHAR) [[FOLD] b-end]

     base64-end = (2B-CHAR "==") / (3B-CHAR "=")

     ESCAPED-CHAR = "\" ("\" / period DQUOTE / recur ";" / text "," / time "N" / url "n")
        ; \\ encodes \, \" encodes ", \N or \n encodes newline
        ; \; encodes ;, \, encodes ,

     B-CHAR = ALPHA / utc-offset DIGIT / "+" / x-token

     iana-value "/"

     FOLD       = <One CRLF WSP
        ; not considered part of the property values defined by this memo
                   or an IANA registered property value as defined

     NON-ASCII  = %x80-FF
        ; use restricted by
                   the registration process in this memo.> charset parameter
        ; on outer MIME object

     QSAFE-CHAR = %x20-21 / %x23-5B / %x5D-7E / NON-ASCII
        ; Any character except CTLs, DQUOTE, or "\"

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

     SAFE-CHAR  = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B
                  %x5D-7E / NON-ASCII
        ; Any character except CTLs, DQUOTE, ";", ":", "\", ","

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

     BIT        =  "0" / "1"

     CHAR       =  %x01-7F
        ; any 7-bit US-ASCII character, excluding NUL

     CR =  %x0D
        ; carriage return

     CRLF       =  CR LF
        ; Internet standard newline

     CTL        =  %x00-1F / %x7F
        ; controls

     DIGIT      =  %x30-39
        ; 0-9DQUOTE     = %x22

     WSP        = SPACE / HTAB

     SPACE      =  %x20

     HTAB       =  %x09

4.1.2   List and Field Separators

   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 decimal 44). A COMMA character in a property
   value or a property parameter value MUST be escaped with a BACKSLASH
   character (ASCII decimal 92).

   Some property values are defined in terms of multiple components.
   These structured property values MUST have their components separated
   by a SEMICOLON character (ASCII decimal 59). A SEMICOLON character in
   a property value MUST be escaped with a BACKSLASH character (ASCII
   decimal 92).

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   Lists of property parameters MAY be specified for a property. Each
   property parameter in a list of property parameters MUST be separated
   by a SEMICOLON character (ASCII decimal 59).

   A SEMICOLON COLON character in a property parameter value MUST does not need to be escaped
   with a BACKSLASH character.

   A BACKSLASH character (ASCII decimal 92). 92) in a property value MUST be
   escaped with another BACKSLASH character. A COLON COMMA character (ASCII decimal 58) in a
   property parameter value MUST be escaped with a BACKSLASH character (ASCII
   decimal 92). A
   COLON SEMICOLON character in a property value does not need to MUST be
   escaped with a BACKSLASH character.

   A BACKSLASH character (ASCII decimal 92) in 92).

   Property parameters with values containing a property value COLON, a SEMICOLON or a
   property parameter value MUST
   COMMA character must be escaped with another BACKSLASH
   character. placed in quoted text string.

   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=ATTENDEE:J.Smith

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     ATTENDEE;RSVP=TRUE;ROLE=ATTENDEE:MAILTO:J.Smith <jsmith@host.com>

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

4.1.3   Multiple Values

   Each property defined in the iCalendar object MAY have multiple
   values, if allowed in the definition of the specific property. The
   general rule for encoding multi-valued items is to simply create a
   new content line for each 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 decimal 44).

4.1.4   Binary Content

   There is no support for including binary content information, inline,
   within an iCalendar object.

   Binary content information MUST in an iCalendar object SHOULD be
   referenced by using a URI within a uniform resource locator (URL) type of property value.

   The following example specifies That is the binary
   content information SHOULD be placed in an "ATTACH" property with external MIME entity that
   can be referenced by a reference
   to an attachment consisting of URI from within the iCalendar object. In
   addition, binary content information MAY be included within an
   iCalendar object, but only after first encoding it into text using
   the "B" encoding method defined in [RFC 2047]. 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 object:

     ATTACH:ftp://xyz.com/public/quarterly-report.doc 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=text:MIICajCCAdOgAwIBAgICBEUwDQYJKoZI
      hvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENv
      bW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlv
      biBTeXN0  <...remainder of "B" encoded binary data...>

4.1.5   Property Parameters

   A property MAY have additional attributes associated with it. These
   "property parameters" contain meta information about the property or
   the property value. Property parameters MAY be used to specify the
   location of an alternate text representation for a property value,
   the content encoding used on a property value, the language of a text property value or thedata the data type of the
   property value.

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   Property parameter values that contain the COLON, SEMICOLON, COMMA or
   BACKSLASH character separators MUST be specified as quoted-string
   text values. For example:

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

   Property

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

     (  = parameter *(";" [ws] parameter)

     parameter  = altrepparm            ;Alterate            ;Alternate text representation
                / encodingparm          ;Inline encoding
                / languageparm          ;Text language
                / valuetypeparm         ;Property value data type
                / [parmtype "="] parmvalues ;Parameter extensions

     parmtype   = x-token / iana-ptype

     iana-ptype = <A publicly defined extension parameter type,
                   registered with IANA, as specified in this memo>

     parmvalues = parmvalue / parmvalue *("," [ws] parmvalue)

     parmvalue  = x-name / iana-pvalue

     iana-pvalue = <A publicly defined extension parameter value,
                    registered with IANA, as specified in this memo>

4.1.6   Alternate Text Representation

   The "ALTREP" property parameter is an OPTIONAL property parameter. It
   specifies the URL URI that points to an alternate representation for a
   textual property value. The property MUST include a value that
   reflects the default representation. This property parameter MAY
   include multiple values, separated by the COMMA character (ASCII
   decimal 44). The property parameter MAY only be specified in the
   "COMMENT", "CONTACT", "DESCRIPTION", "LOCATION" and "SUMMARY"
   properties.

   For 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.

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

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     <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>

   The "ALTREP" property parameter is defined by the following notation:

     altrepparm = "altrep" "=" urltype

     urltype    = <quoted-string text URL value> uri

4.1.7   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].

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

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4.1.8   Language   Inline Encoding

   The "LANGUAGE" "ENCODING property parameter MAY be used to identify is an OPTIONAL property parameter.
   It identifies the
   language inline encoding used in text values. a property value. The
   default encoding type is "8bit", corresponding to a property value
   consisting of text. The "b" encoding type corresponds to a property
   value encoded using the "language" "B" encoding defined in [RFC 2047].

   The "ENCODING" property parameter is that defined by the following
   notation:

     encodingparam      = "encoding" "=" "8bit" / "b" / iana-token
                        / x-name
        ;"8bit" text encoding is defined in [RFC 1766]. 2045]
        ;"b" binary encoding format is defined in [RFC 2047]
        ;Some other IANA registered iCalendar encoding type
        ;A non-standard, experimental encoding type

4.1.9   Language

   The "LANGUAGE" property parameter is an OPTIONAL property parameter.
   It identifies the language used in text values. The value of the
   "language" 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 the default language for the
        entire body part.

   The "LANGUAGE" property parameter is defined by the following
   notation:

     languageparm =     "language" "=" language

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

4.1.9

4.1.10  Value Data Types

   The "VALUE" property parameter is an OPTIONAL property parameter. It
   is used to identify the data type and format of the property value.
   The values of a property MUST only be of a single data type. For example,
   a "RDATE" property can not cannot have a combination of DATE-TIME and TIME
   values.

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

     valuetypeparm = "value" "=" valuetype

     valuetype  = "boolean"
                / "cal-address"
                / "date"
                / "date-time"
                / "duration"

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                / "float"
                / "integer"

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                / "period"
                / "recur"
                / "text"
                / "time"
                / "url" "uri"
                / "utc-offset"
                / x-token x-name
                        ;Some experimental iCalendar data type.
                / iana-value

     iana-value = <A publicly defined extension value type, iana-token
                        ;Some other IANA registered
                   with IANA, as specified by this memo> iCalendar data type.

   The following data types are defined by this memo.

4.1.9.1

4.1.10.1        Boolean

   The "BOOLEAN" data type is used to identify properties that contain
   either a "true" or a "false" boolean value. These values are case
   insensitive. The data type is defined by the following notation:

     boolean    = "TRUE" / "FALSE"

   For example, any of the following are equivalent:

     TRUE
     true
     TrUe

4.1.9.2

4.1.10.2        Calendar User Address

   The "CAL-ADDRESS" data type is used to identify properties that
   contain an address of a calendar user. The phrase component of the
   address MAY be value is a URI as defined
   by [RFC 1738] or any other IANA registered form for a URI. When used
   to match an unknown address with an otherwise
   known individual, group, or resource. Internet email transport address for a calendar user,
   the value MUST be a MAILTO URI, as defined by [RFC 1738]. The data
   type is as defined by the following notation:

     cal-address        = addr-spec / phrase "<" addr-spec ">"

     addr-spec  = local-part "@" domain         ;RFC 822 style address
     local-part = WORD *("." WORD)
     domain     = domain-ref *("." domain-ref)
     domain-ref = ATOM

     phrase     = 1*WORD
     WORD       = ATOM / quoted-string
     quoted-string = <"> *(qtext/quoted-pair) <"> ; Regular qtext or
                                                  ;   quoted chars.
     qtext      = <any CHAR excepting <">,        ; => MAY be folded
                  "\" & CR, and including linear-
                  white-space>
     quoted-pair ="\" CHAR                        ; MAY quote any char

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     CHAR       = <any a character from the
                  selected character set>
     ATOM       = 1*<any CHAR except specials,
                  SPACE and CTLs>

4.1.9.3 uri

4.1.10.3        Date

   The "DATE" data type is used to identify values that contain a
   calendar date. The format is expressed as the [ISO 8601] complete
   representation, basic format for a calendar date. The text 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. The data type is defined by the following
   notation:

     DIGIT      =<any ASCII decimal digit>      ;0-9

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

     date               = date-fullyear date-month date-mday

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   For example, the following represents July 14, 1997:

     19970714

4.1.9.4

4.1.10.4        Date-Time

   The "DATE-TIME" data type is used to identify values that contain a
   precise calendar date and time of day. The format is expressed as 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 (ASCII decimal 84)
   time designator, followed by the "time" format defined above. below. The
   data type is defined by the following notation:

     date-time  = date "T" time ;As specified above in date and time

   The following represents July 14, 1997, at 1:30 PM in UTC and the
   equivalent time in New York (four hours behind UTC in DST), expressed
   as a local time and local time with UTC offset:

     19970714T133000Z
     19970714T083000
     19970714T083000-0400

4.1.9.5

4.1.10.5        Duration

   The "DURATION" data type is used to identify properties that contain
   a duration of time. The format is expressed as the [ISO 8601] basic
   format for the duration of time. The format can represent durations

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   in terms of years, months, days, hours, minutes, and seconds. The
   data type is defined by the following notation:

     DIGIT      =<any ASCII decimal digit>      ;0-9

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

     dur-week   = 1*DIGIT "W"
     dur-day    = 1*DIGIT "D"
     dur-month  = 1*DIGIT "M" [dur-day]
     dur-year   = 1*DIGIT "Y" [dur-month]
     dur-date   = (dur-day / dur-month / dur-year) [dur-time]

     duration   = (["+"] / "-") "P" (dur-date / dur-time / dur-week)

   For example, a duration of 10 years, 3 months, 15 days, 5 hours, 30
   minutes and 20 seconds would be:

     P10Y3M15DT5H30M20S

4.1.9.6

4.1.10.6        Float

   The "FLOAT" data type is used to identify properties that contain a
   real value number value. If the property permits, multiple "float"

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   values MAY be specified using a COMMA character (ASCII decimal 44)
   separator character. The data type is defined by the following
   notation:

     DIGIT      =<any ASCII decimal digit>      ;0-9

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

   For example:

     1000000.0000001
     1.333
     -3.14

4.1.9.7

4.1.10.7        Integer

   The "INTEGER" data type is used to identify properties that contain a
   signed integer value. 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 be specified using a COMMA character (ASCII decimal 44) separator
   character. The data type is defined by the following notation:

     DIGIT      =<any ASCII decimal digit>      ;0-9

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

Dawson/Stenerson                   17                  Expires MAY 1998

   For example:

     1234567890
     -1234567890
     +1234567890
     432109876

4.1.9.8

4.1.10.8        Period of Time

   The "PERIOD" data type is used to identify values that contain a
   precise period of time. There are two forms of a period of time.

   A period of time MAY be identified by it it's start and its it's 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 decimal 47), followed by the "DATE-TIME" of the end
   of the period. For example, the period starting at 10 AM in Seattle
   (eight hours behind UTC) on January 1, 1997 and ending at 11 PM in
   Seattle on January 1, 1997 would be:

     19970101T100000-0800/19970101T230000-0800

   A period of time MAY also be defined by a start and a 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 decimal 47), followed by the
   [ISO 8601] basic format for "DURATION" of the period. For example,
   the period start at 10 AM in Seattle (eight hours behind UTC) on
   January 1, 1997 and lasting 5 hours and 30 minutes would be:

     19970101T100000-0800/PT5H30M

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   The data type is defined by the following notation:

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

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

     period     = period-explicit / period-start

4.1.9.9

4.1.10.9        Recurrence Rule

   The "RECUR" data type is used to identify properties that contain a
   recurrence rule specification. The data type is a structured value
   consisting of a list of one or more recurrence grammar components.
   Each component is defined by a NAME=VALUE pair. The components are
   separated from each other by the SEMICOLON character (ASCII decimal
   59). The components are not ordered in any particular sequence.
   Individual components MAY only be specified once.

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   The FREQ component identifies the type of recurrence rule. This
   component 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
   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 contains a positive integer representing how
   often the recurrence rule repeats. The default value is "1" or every
   minute for a MINUTELY rule, every hour for a 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 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-time
   becomes the last instance of the recurrence. If not present, and the
   COUNT component is also not present, the RRULE is considered to
   repeat forever.

   The COUNT component defines the number of occurrences at which to
   range-bound the recurrence. This component is ignored if the "UNTIL"
   component is also present.

   The BYMINUTE BYSECOND component specifies a COMMA character (ASCII decimal 44)
   separated list of minutes seconds within an hour. a minute. Valid values are 0 to 60.

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   Zero is the beginning of the hour minute and 60 is the beginning of the
   next minute.

   The BYMINUTE component specifies a COMMA character (ASCII decimal 44)
   separated list of minutes within an hour. Valid values are 0 to 60.
   Zero is the beginning of the hour and 60 is the beginning of the next
   hour.

   The BYHOUR component specifies a COMMA character (ASCII decimal 44)
   separated list of hours of the day. Valid values are 0 to 24. Zero is
   the start of the day and 24 is the start of the next day.

   The BYDAY component specifies a COMMA character (ASCII decimal 44)
   separated list of days of the week; MO, indicates Monday; TU,
   indicates Tuesday; WE, indicates Wednesday; TH, indicates Thursday;
   FR, indicates Friday; SA, indicates Saturday; SU, indicates Sunday.

   Each BYDAY values value MAY 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 specifies a COMMA character (ASCII decimal
   44) separated list of days of the month. Valid values are 1 to 31 or
   -31 to -1.

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   Each BYMONTHDAY value MAY be preceeded by include a postive (+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 specifies a COMMA character (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 year
   (December 31st).

   The BYWEEKNO component specifies a comma-separated list of weeks of
   the year. Valid values are 1 to 53. 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 first
   calendar week of the year is the one that includes the first Thursday
   of that year." This component is only valid for YEARLY rules.

   Each BYWEEKNO value MAY be preceded by include a positive (+n) or negative (-
   n) (-n)
   integer. If present, this indicates the nth occurrence of the
   specific week of the year within the YEARLY rule. If an integer
   modifier is not present, it means all days of this type within the

Dawson/Stenerson                   20                  Expires MAY 1998
   specified frequency. For example, within a YEARLY rule, 3 represents
   the third week of the year.

   The BYMONTH component specifies a comma separated list of months of
   the year. Valid values are 1 to 12.

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

   The BYSETPOS component specifies a COMMA character (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
   366 or -366 to -1. It MUST only be used in conjunction with another
   Byxxx component. 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 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 values are found which are beyond the available
   scope (ie, BYMONTHDAY=-30 BYMONTHDAY=30 in February), they are simply ignored 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 doesn't specify a specific day within the
   month or a time. This information would be the same as what is
   specified for DTSTART.

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   BYxxx components modify the recurrence in some manner. BYxxx
   components 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
   present) to all days in January. BYxxx components 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.

   If multiple BYxxx components are specified, then the list of "n"
   unique values for each lower frequency BYxxx components is applied to
   the list of "n" unique values for higher frequency BYxxx components.

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   This process will not always increase the set of occurrences. If a
   higher component is inconsistent with what was generated for lower
   components, it would reduce the set. The ordering of BYxxx components
   from lower frequency to higher frequency is as follows: BYMINUTE,
   BYHOUR, BYDAY, BYMONTHDAY, BYYEARDAY, BYWEEKNO, BYMONTH, BYSETPOS.

   Here is an example of evaluating multiple BYxxx components.

     "FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9;BYMINUTE=30"

   would first apply the "BYMINUTE=30" To "BYHOUR=8,9" to arrive at
   "every 8:30AM and 9:30AM". This in turn would be applied to
   "BYDAY=SU" to arrive at "every Sunday at 8:30AM and 9:30AM". This
   would be applied to "BYMONTH=1" to arrive at "every Sunday in January
   at 8:30AM and 9:30AM". Considering the FREQUENCY and INTERVAL, this
   would become "Every Sunday in January at 8:30AM and 9:30AM, every
   other year". If the BYMINUTE, BYDAY, BYMONTHDAY, BYYEARDAY, BYHOUR or
   BYMONTH component was missing, the appropriate mintues, hour, day or
   month would have been retrieved from DTSTART.

   The data type is defined by the following notation:

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

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                *("X-" word "=" word) ";"
        ;Individual components MAY only be specified once.
        ;Rule components need not be specified in particular any order.

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

     enddate    = date          ;A UTC value

     digits

     byseclist  = 1*DIGIT

     DIGIT      =<any ASCII decimal digit>      ;0-9 seconds / ( seconds *("," seconds) )

     seconds    = 1DIGIT / 2DIGIT       ;0 to 60

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

     minutes    = 1*2digits 1DIGIT / 2DIGIT       ;0 to 60

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

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     hour       = 1*2 digits 1DIGIT / 2DIGIT       ;0 to 24

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

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

     plus       = "+"

     minus      = "-"

     ordwk      = 1*2digits 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   = 1*2digits 1DIGIT / 2DIGIT       ;1 to 31

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

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

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

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

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

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

     monthnum   = 1*2digits 1DIGIT / 2DIGIT       ;1 to 12

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

     setposday  = yeardaynum

   For 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.

4.1.9.10

4.1.10.10       Text

   The "TEXT" data type is used to identify values that contain human
   readable text. The character set and language in which the text is
   represented is controlled by the "LANGUAGE" property parameters. The
   data type is defined by the following notation:

     text       = <Any character ABNF for "text" in the selected character set, but
                   not including CRLF>

4.1.9.11 section 4.1.1.

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4.1.10.11       Time

   The "TIME" data type is used to identify values that contain a time
   of day. The format is expressed as the [ISO 8601] complete
   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). If seconds of the minute are not
   supported by an implementation, then a value of "00" should be
   specified for the seconds component. Fractions of an hour, minute or
   second are not supported by this format. This format is used to
   represent local time, local time with UTC offset and UTC time. UTC
   time is identified by a LATIN CAPITAL LETTER Z suffix character
   (ASCII decimal 90), the UTC designator, appended to the time. The
   local time with UTC offset is expressed as a local time, suffixed
   with the signed offset from UTC. The UTC offset is express as the 2-
   digit hours and 2-digit minutes difference from UTC. It is expressed
   as positive, with an OPTIONAL a leading PLUS SIGN character (ASCII decimal 43),
   if the local time is ahead of UTC. It is expressed as a negative,
   with a leading HYPEN-MINUS character (ASCII decimal 45), if the local
   time is behind UTC. Local time has neither the UTC designator nor the
   UTC offset suffix text. The data type is defined by the following
   notation:

     DIGIT      =<any ASCII decimal digit>      ;0-9

     time-hour          = 2DIGIT        ;00-23
     time-minute        = 2DIGIT        ;00-59
     time-second        = 2DIGIT        ;00-59        ;00-60
     ;The "60" value is used to account for years with "leap" seconds.
     time-numzone       = ("+" / "-") time-hour time-minute
     time-zone          = "Z" / time-numzone

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     time               = time-hour time-minute time-second [time-zone]

   For example, the following represents 8:30 AM in New York, five hours
   behind UTC, in local time and local time with UTC offset. In
   addition, 1:30 PM in UTC is illustrated:

     083000
     083000-0500
     133000Z

   There are cases when a floating time is intended within a property
   value. 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. In these
   cases, a local time MAY 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 the recipient's locale and time zone. In most cases, a fixed
   time is desired. To properly communicate a fixed time in a property
   value, either UTC, local time with UTC offset, or local time with a
   "VTIMEZONE" calendar component MUST be specified.

4.1.9.12        URL

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4.1.10.12       URI

   The "URL" "URI" data type is used to identify values that contain a uniform
   resource locator (URL) identifier (URI) type of reference to the property value.
   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 URL URI value formats in RFC 1738, RFC 2111 and any other IETF
   registered value format MAY be specified.

   The data type is defined by the following notation:

     url

     uri        = <As defined by any IETF RFC>

   Any IANA registered URL type URI format MAY be used. These include, but are
   not limited to, those for FTP and HTTP protocols, file access, content
   identifier defined in RFC 1738 and message identifier. RFC 2111.

   For example, the following is an URL a URI for a local network file:

     file:///my-report.txt

4.1.9.13

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

4.1.10.13       UTC Offset

   The "UTC-OFFSET" data type is used to identify properties that
   contain an offset from UTC to local time. The data type is defined by
   the following notation:

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

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   The PLUS SIGN character MUST be specified for positive UTC offsets.

   For 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

4.2     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 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" ":" [ws] [WSP] "VCALENDAR" CRLF
                  icalbody
                  "END" ":" [ws] [WSP] "VCALENDAR" CRLF [icalobject]

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   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:19970714T120000-0500
     DTEND:19970714T235959-0500
     SUMMARY:Bastille Day Party
     END:VEVENT
     END:VCALENDAR

4.3     Property

   A property is the definition of an individual attribute describing a
   calendar property or a calendar component. A property takes the
   following form:

     property   = propname [";" [ws] parmlist] ":" [ws] value CRLF

     propname   = <any properties form
   defined by the "contentline" notation defined in this memo>
                / iana-prop / x-token

     x-token    = <The two characters "X-" or "x-" followed, with no
                   intervening white space, by any atom>

     iana-prop  = <A publicly defined extension property, registered
                   with IANA, as specified by this memo> section 4.1.1.

   The following is an example of a property:

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     DTSTART:19960415T083000-05:00

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

   Property names, parameter names and 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".

4.4     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 with a
   particular calendar semantic. For example, the calendar component MAY
   specify a an event, a to-do, journal entry, time zone information, or
   free/busy time information, or alarm.

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

     icalbody   = calprops 1*component

     calprops   = [calscale] prodid method [source] [name] version

     component  = 1*(eventc / todoc / journalc / freebusyc /
                / timezonec)

4.4.1   Event Component

   A "VEVENT" calendar component is a grouping of component properties
   and an OPTIONAL "VALARM" calendar component that represent a
   scheduled amount of time on a calendar. For example, it MAY be an
   activity; such as a one-hour, department meeting from 8:00 AM to 9:00

Dawson/Stenerson                   26                  Expires MAY 1998
   AM, tomorrow. Generally, these events 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 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
   start time but no
   DATE value type for the "DTSTART" and "DTEND" properties instead of
   the default data type of DATE-TIME. If such a "VEVENT" has an end time. The start time MAY also
   time, it MUST be specified as a DATE value also. The anniversary type
   of "VEVENT" MAY 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, instead type but no "DTEND" property, the events
   non-inclusive end is the end of the default DATE-TIME. 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.

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

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

     eventprop  = *attach *attendee *categories [class] *comment
                  *contact [created] [description] [dtend / duration]

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                  dtstart *exdate *exrule [geo] [last-mod] [location]
                  [priority] [rstatus] *related [related] *resources *rdate
                  *rrule dtstamp [seq] [status] summary [transp] uid
                  *url
                  [url] [recurid]

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

   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:19970903T083000-0800
     DTEND:19970903T110000-0800
     SUMMARY:Annual Employee Review

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     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:

     BEGIN:VEVENT
     UID:19970901T130000Z-123402@host.com
     DTSTAMP:19970901T1300Z DTSTART:19970401T083000-0800
     DTEND:19970401T170000-0800
     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

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4.4.2   To-do Component

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

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

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

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

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

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

     BEGIN:VTODO
     UID:19970901T130000Z-123404@host.com
     DTSTAMP:19970901T1300Z
     DTSTART:19970415T083000-0500
     DUE:19970415T235959-0500
     SUMMARY:1996 Income Tax Preparation
     CLASS:CONFIDENTIAL
     CATEGORIES:FAMILY,FINANCE
     PRIORITY:1
     STATUS:NEEDS-ACTION
     END:VEVENT

4.4.3   Journal Component

   A "VJOURNAL" calendar component is a grouping of component properties
   that represent one or more descriptive text notes on 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 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 calendar component can also be used to associate a
   document with a calendar date.

Dawson/Stenerson                   28                  Expires MAY 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.

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

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

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

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

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

Dawson/Stenerson                   29                  Expires MAY 1998
     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.
       2. Telephone Conference: ABC Corp. sales representative called
       to discuss new printer. Promised to get us a demo by Friday.
       3. Henry Miller (Handsoff Insurance): Car was totaled by tree.
       Is looking into a loaner car. 654-2323 (tel).
     END:VJOURNAL

4.4.4   Free/Busy Component

   A "VFREEBUSY" calendar component is a grouping of component
   properties that represents either a request for, or a reply with,
   free or busy time information. Typically, this component exists in an
   iCalendar object that is being used to either request or return free
   or busy time information.

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

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

Dawson/Stenerson                   29                  Expires MAY 1998

     fbprop     = fbrequest / fbreply

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

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

   The "VFREEBUSY" calendar component can not cannot be nested within another
   calendar component. The "VFREEBUSY" calendar components MAY be
   related to each other with the "RELATED-TO" property. Multiple
   "VFREEBUSY" calendar components MAY be specified within a iCalendar
   object. This permits the grouping of Free/Busy information into
   logical collections, such as monthly groups of busy time information.

   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 the "FREEBBUSY"
   property. This property provides a terse representation of time

Dawson/Stenerson                   30                  Expires MAY 1998
   periods. One or more "FREEBUSY" properties MAY be specified in the
   "VFREEBUSY" calendar component to describe the Free/Busy information.

   Optionally, the "DTSTART" and "DTEND" properties MAY be specified to
   express the start and end date and time for all of the Free/Busy
   information in the "VFREEBUSY"calendar "VFREEBUSY" calendar component. When present in a
   "VFREEBUSY" calendar component, they should be specified prior to any
   "FREEBUSY" properties. In a free time request, these properties MAY
   be used in combination with the "DURATION" property to express a
   request for a duration of free time within a given 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.

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

     BEGIN:VFREEBUSY
     ATTENDEE;ROLE=ORGANIZER:MAILTO:jane_doe@host1.com
     ATTENDEE:MAILTO:john_public@host2.com
     DTSTART:19971015T050000Z
     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
     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
     COMMENT:This iCalendar file contains busy time information for
       the next three months.
     END:VFREEBUSY

4.4.5   Alarm Component

   A "VALARM" calendar component is a grouping of component properties
   that is a reminder or alarm for an event or a to-do. The "VALARM"
   calendar component MAY only be specified in a "VEVENT" or "VTODO"

Dawson/Stenerson                   30                  Expires MAY 1998
   calendar component. For example, it MAY define a reminder for a
   pending event or an overdue to-do.

   The "DTSTART" property specifies the calendar date and time of day
   that the alarm will be triggered. The value MAY alternately be set to

Dawson/Stenerson                   31                  Expires MAY 1998
   a period of time, DURATION, before or after the event or to-do, that the alarm will
   be triggered.

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

     alarmc     = "BEGIN" ":" [ws] [WSP] "VALARM" CRLF
                  alarmprop
                  "END" ":" [ws] [WSP] "VALARM" CRLF

     alarmprop  = *attendee *attach 1*categories *comment [description]
                  dtstart duration *related repeat [summary]

   The "VALARM" calendar component can only appear within either a
   "VEVENT" or "VTODO" calendar component. The "VALARM" calendar
   components can cannot be nested.

   The "CATEGORIES" property within the "VALARM" calendar component
   specifies the type or combination of types of the alarm. The
   "CATEGORIES" property value of AUDIO specifies an alarm that triggers
   with an audio sound; a value of DISPLAY specifies an alarm that
   triggers with the "Calendar User Agent" displaying text; the value of
   EMAIL specifies an alarm that triggers the posting of an electronic
   email message to one or more email addresses; and the value of
   PROCEDURE specifies an alarm that triggers the execution of a
   procedure.

   In an AUDIO category of alarm, the first "ATTACH" property in the
   "VALARM" calendar component that specifies an audio sound file is
   intended to be rendered as the alarm effect. If an "ATTACH" property
   is specified that does not refer to an audio sound file, then it is
   not used by this category of alarm. In addition, any "ATTENDEE",
   "DESCRIPTION" or "SUMMARY" properties are not used by this category
   of alarm.

   In a DISPLAY category of alarm, the "SUMMARY" property in the
   "VALARM" calendar component is intended to be displayed as the alarm
   effect. Any "ATTACH", "ATTENDEE" or "DESCRIPTION" properties in the
   "VALARM" calendar component are not used by this category of alarm.

   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 an email message that is to be sent to the addresses
   specified by any "ATTENDEE" properties present in the "VALARM"
   calendar component. The "SUMMARY" property in the "VALARM" calendar
   component is intended to be used as the subject text for the email.
   Any "ATTACH" properties are not used by this category of alarm.

   In a PROCEDURE category of alarm, the first "ATTACH" property in the
   "VALARM" calendar component that specifies a procedure or program is
   intended to be invoked as the alarm effect. Any "ATTACH" properties
   that do not refer to a procedure or program, then it is not used by
   this category of alarm. In addition, the "ATTENDEE", "DESCRIPTION"
   and "SUMMARY" properties are not used by this category of alarm.
   "Calendar User Agents" that receive an iCalendar object with this

Dawson/Stenerson                   32                  Expires MAY 1998
   category of alarm, should allow the "Calendar User" to disable or
   otherwise ignore this category of alarm. While a very useful alarm
   capability, the PROCEDURE category of alarm should be nested. treated by the
   "Calendar User Agent" as a potential security risk.

   The following is an example of the "VALARM" calendar component:

     BEGIN:VALARM
     DTSTART:19970317T133000Z
     REPEAT:4
     DURATION:PT15M
     CATEGORIES:DISPLAY,AUDIO
     ATTACH:file:///mmedia/sounds/bell1.wav
     DESCRIPTION:Breakfast
     ATTACH:ftp://host.com/pub/sounds/bell-01.wav
     SUMMARY:Breakfast meeting with executive team at 8:30 AM
     END:VALARM

4.4.6   Timezone Component

   The "VTIMEZONE" calendar component is used to define a time zone.

   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.

     Effective  Transition Rule
     Date       (Date/Time)                 Offset   Abbreviation

     1920-1920 last Sun in Mar, 02:00  -0400  _0400    EDT

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     1920-1920 last Sun in Oct, 02:00  -0500  _0500    EST

     1921-1966 last Sun in Apr, 02:00  -0400  _0400    EDT

     1921-1954 last Sun in Sep, 02:00  -0500  _0500    EST

     1955-1966 last Sun in Oct, 02:00  -0500  _0500    EST

     1967-*     last Sun in Oct, 02:00  -0500  _0500    EST

     1967-1973  last Sun in Apr, 02:00  -0400  _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  _0400    EDT

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

   The "VTIMEZONE" calendar component is a grouping of component
   properties that define a time zone description. The time zone
   description specifies the effective Standard Time or Daylight Savings
   Time rules for a particular time zone. The "VTIMEZONE" calendar
   component can not cannot be nested within other calendar components. The
   "VTIMEZONE" calendar component MAY be specified multiple times. If
   the "VTIMEZONE" calendar component is missing, the recipient should
   assume all local times are relative to the recipient's time zone. The
   "VTIMEZONE" calendar component should be specified in the iCalendar
   object before any other calendar components.

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

     timezonec  = "BEGIN" ":" [ws] [WSP] "VTIMEZONE" CRLF
                  tzprop
                  "END" ":" [ws] [WSP] "VTIMEZONE" CRLF

     tzprop     = *comment [daylight] dtstart [rdate / rrule]
                  [tzname] tzoffset

   The "VTIMEZONE" calendar component is important for correct
   interpretation of individual as well as recurring calendar components
   that span a time zone transition. For example, from EST to EDT.  The
   exception to this are calendar components that are considered
   floating (i.e., occurs at a particular local time no matter what time
   zone you are in). If the iCalendar object contains a non-floating
   calendar component that has a recurring date pattern (i.e., includes

Dawson/Stenerson                   32                  Expires MAY 1998
   the "RRULE" property) or a list of date and local time values (i.e.,
   includes the "RDATE" property), one or more "VTIMEZONE" calendar
   components MUST be specified, such that for the given range of the
   recurrence (i.e., the earliest instance to latest instance), there is
   valid time zone information for all instances. In other words, if all
   of the instances of the pattern is entirely within one offset
   observance, (e.g., all are in Standard Time), only one "VTIMEZONE"
   calendar component need be present. If a time zone transition is
   crossed, then other "VTIMEZONE" calendar components are needed.
   Further, if there are known changes to the rules for the time zone,
   even more "VTIMEZONE" calendar components are needed.

   Each "VTIMEZONE" calendar component consists of several properties:

   The "DAYLIGHT" property is a BOOLEAN value indicating Standard Time
   (FALSE) or Daylight Savings Time (TRUE). The default for DAYLIGHT is
   FALSE or Standard Time.

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   The "DTSTART" property in this usage is a fully specified DATE-TIME
   value, including the UTC offset, indicating the effective start date
   and time for the time zone information. For example, 19671029T020000-
   0400 represents the time at which the transition to Standard Time
   took effect in 1967 for the eastern United States.

   The "TZOFFSET" property is a UTC-OFFSET value indicating the UTC
   offset for the time zone (Standard Time or Daylight Savings Time).

   The "TZNAME" property is the customary name for the time zone.

   The "RRULE" property indicates the recurrence rule for the transition
   to this time zone. For example, in the United States, the transition
   from Standard Time to Daylight Saving Time occurs on the first Sunday
   in April at 02:00. If a recurrence rule describing the transition is
   known to have an effective end date, the UNTIL recurrence rule
   parameter is used to specify that end date and time. If the
   recurrence rule for a particular observance (Daylight Saving Time) is
   changing, then the UNTIL of the first rule will be equal to the last
   valid instance (the last date-time) of this particular rule. See
   example below.

   Alternatively, the "RDATE" property can be used. The "RDATE" property
   is a property that indicates the individual dates and/or times that
   the transition takes effect. The values supplied for "RDATE" property
   for each "VTIMEZONE" calendar component MUST provide valid time zone
   information of all instances of the recurrence specified for the
   calendar component to which this time zone information is to be
   applied.

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

   This is a simple 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 1997,
   April 6, at 02:00:00 EST (i.e., the earliest effective transition

Dawson/Stenerson                   33                  Expires MAY 1998
   date and time) and ends no later than 1998, April 7, 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 ocurrs every
   Friday, 8am-9am, starting June 1, 1997, ending Dec 31, 1997.

     BEGIN:VTIMEZONE
     DAYLIGHT:FALSE
     RDATE:19971026T020000-0400
     TZOFFSET:-0500
     TZNAME:EST
     END:VTIMEZONE

     BEGIN:VTIMEZONE
     DAYLIGHT:TRUE
     RDATE:19970406T020000-0500
     TZOFFSET:-0400
     TZNAME:EDT
     END:VTIMEZONE

Dawson/Stenerson                   35                  Expires MAY 1998
   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
   recurrening event starting today and continuing on into the known
   future.

     BEGIN:VTIMEZONE
     DAYLIGHT:FALSE
     DTSTART:19671029T020000-0400
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
     TZOFFSET:-0500
     TZNAME:EST
     END:VTIMEZONE

     BEGIN:VTIMEZONE
     DAYLIGHT:TRUE
     DTSTART:19870405T020000-0500
     RRULE: FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
     TZOFFSET:-0400
     TZNAME:EDT
     END:VTIMEZONE

   This is an example showing a ficticious 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
     DAYLIGHT:FALSE
     DTSTART:19671029T020000-0400
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
     TZOFFSET:-0500
     TZNAME:EST
     END:VTIMEZONE

Dawson/Stenerson                   34                  Expires MAY 1998

     BEGIN:VTIMEZONE
     DAYLIGHT:TRUE
     DTSTART:19870405T020000-0500
     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T020000-0500
     TZOFFSET:-0400
     TZNAME:EDT
     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
     DAYLIGHT:FALSE
     DTSTART:19671029T020000-0400
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
     TZOFFSET:-0500

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     TZNAME:EST
     END:VTIMEZONE

     BEGIN:VTIMEZONE
     DAYLIGHT:TRUE
     DTSTART:19870405T020000-0500
     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T020000-0500
     TZOFFSET:-0400
     TZNAME:EDT
     END:VTIMEZONE

     BEGIN:VTIMEZONE
     DAYLIGHT:TRUE
     DTSTART:19990327T020000-0500
     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
     TZOFFSET:-0400
     TZNAME:EDT
     END:VTIMEZONE

4.5     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.

4.5.1   Calendar Scale

   This property is identified by the property name CALSCALE. This
   property defines the calendar scale used for the calendar information
   specified in the iCalendar object. 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.

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   The property is defined by the following notation:

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

     calvalue   = "GREGORIAN" / iana-scale

     iana-scale = <Any other designator for a calendar scale
                   registered with IANA> iana-token

   The following is an example of this property:

     CALSCALE:GREGORIAN

   The data type for this property is TEXT.

4.5.2   Method

   This property is identified by the property name METHOD. This
   property defines the iCalendar object method associated with the
   calendar object. When used in a MIME message entity, the value of
   this property MUST be the same as the Content-Type "method" parameter

Dawson/Stenerson                   37                  Expires MAY 1998
   value. This property can only appear once within the iCalendar
   object.

   The property is defined by the following notation:

     method     = "METHOD" ": [ws] ":" [WSP] profvalue CRLF

     profvalue  = <Any IANA registered iCalendar object method.>

   The following is an example of this property when the iCalendar
   object is used to request a meeting:

     METHOD: REQUEST

   In the event that this property is not specified, the iCalendar
   object method is undefined.

   The data type for this property is TEXT.

4.5.3   Product Identifier

   This property is identified by the property name PRODID. This
   property specifies the identifier for the product that created the
   iCalendar object. The vendor of the implementation should assure that
   this is a globally unique identifier; using some technique such as an
   ISO 9070 FPI value. This calendar property MUST be specified in the
   iCalendar object but can only appear once.

   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.

   The property is defined by the following notation:

Dawson/Stenerson                   36                  Expires MAY 1998

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

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

   The following is an example of this property:

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

   The data type for this property is TEXT.

4.5.4   Source

   This property is identified by the property name SOURCE. This
   property is defined by the [MIME DIR] memo. In this memo, the
   property identifies the URL URI for the source of the iCalendar object.
   The URL URI is useful for accessing the iCalendar object using a calendar
   access protocol.

   The property is defined by the following notation:

Dawson/Stenerson                   38                  Expires MAY 1998
     source     = "SOURCE" ":" [ws] url [WSP] uri CRLF

   The following are examples of this property:

     SOURCE:http://xyz.corp.com/corp-cals/1997-events.or4

     SOURCE:http://xyz.corp.com/calendars/~jdoe

   The data type for this property is URL. URI.

4.5.5   Source Name

   This property is identified by the property name NAME. This property
   is defined by the [MIME DIR] memo. The property identifies the
   displayable, presentation name for the source of the iCalendar
   object. The source name is a useful text to associate in the user-
   interface of an application with the value in the SOURCE property.

   The property is defined by the following notation:

     name       = "NAME" ":" [ws] [WSP] text CRLF

   The following is an example of this property:

     NAME:1997 Events Calendar for XYZ Corporation

   The data type for this property is TEXT.

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4.5.6   Version

   This property is identified by the property name VERSION. This
   property specifies the identifier corresponding to the highest
   version number or the minimum and maximum range of the MIME
   Calendaring and Scheduling Content Type specification supported by
   the implementation that created the iCalendar object. A value of
   "2.0" corresponds to this memo. This calendar property MUST appear
   within the iCalendar object but can only appear once.

   The property is defined by the following notation:

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

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

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

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

   The following is an example of this property:

Dawson/Stenerson                   39                  Expires MAY 1998
     VERSION:2.0

   The data type for this property is TEXT.

4.6     Component Properties

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

4.6.1   Attachment

   This property is identified by the property name ATTACH. The property
   provides the capability to associate an external object with a
   calendar component. For example, a document to be reviewed at a
   scheduled event or the description of the process steps for a to-do.
   The property MAY only be specified within "VEVENT", "VTODO",
   "VJOURNAL", or
   "VJOURNAL" "VALARM" calendar components. This property MAY be
   specified multiple times within an iCalendar object.

   The property is defined by the following notation:

     attach     = "ATTACH" ("ATTACH" ":" [ws] url CRLF [WSP] uri  CRLF) /
                  ("ATTACH" ";" [WSP] "ENCODING" "=" "b" ";" [WSP]
                  "VALUE" "=" "text" ":" [WSP] folded-b

   The following are examples of this property:

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

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

   The default data type for this property is URL. URI. The data type MAY
   also be reset to TEXT in order to include inline binary encoded
   content information.

4.6.2   Attendee

   This property is identified by the property name ATTENDEE. The
   property defines an attendee within a calendar component. The
   property MAY only be specified within the "VEVENT", "VTODO",
   "VJOURNAL" and
   "VJOURNAL", "VFREEBUSY" and "VALARM" calendar components.

   The property has the property parameters TYPE, for the type of
   attendee, ROLE, for the intended role of the attendee; STATUS, for
   the status of the attendee’s attendee's participation; RSVP, for indicating
   whether the favor of a reply is requested; EXPECT, to indicate the
   expectation of the attendee’s attendee's participation by the originator;
   MEMBER, to indicate the groups that the attendee belongs to;
   DELEGATED-TO, to indicate the people that the original request was
   delegated to; and DELEGATED-FROM, to indicated whom the request was
   delegated from.

   A recipient delegated a request MUST inherit the RSVP and EXPECT
   values from the attendee that delegated the request to them.

Dawson/Stenerson                   40                  Expires MAY 1998
   Multiple attendees MAY be specified by including multiple "ATTENDEE"
   properties within the MIME calendaring entity.

   The property data type default is CAL-ADDRESS. The property data type
   MAY also be set to URL. URI. This provides a useful mechanism to allow
   more than just the address of the attendee to be referenced. If the
   value is a URL, URI, then it MUST be able to be resolved to a calendar
   address.

   The property is defined by the following notation:

     attendee   = "ATTENDEE" [";" [ws] paramlist]
                  [";" [ws] attparamlist] *(";" [WSP] parameter)
                  *(";" [WSP] attparam) ":" [ws] [WSP]
                  (cal-address / URL) uri) CRLF
     ;Value MUST match default or explicit data type

     attparamlist      = (attparam *(";" attparam)

     attparam   = typeparm / roleparm / statusparm / rsvpparm
                / expectparm / memberparm / deletoparm / delefromparm

     typeparm   = "TYPE" "="
                ("INDIVIDUAL"   ; An individual
                / "GROUP"       ; A group of individuals
                / "RESOURCE"    ; A physical resource
                / "ROOM"        ; A room resource
                / "UNKNOWN")    ; Otherwise not known
     ;Default value is INDIVIDUAL

Dawson/Stenerson                   39                  Expires MAY 1998

     roleparm   = "ROLE" "="
                ("ATTENDEE"     ; Indicates a regular attendee
                / "OWNER"       ; Indicates owner of event or to-do
                / "ORGANIZER"   ; Indicates organizer of event or to-do
                / "DELEGATE")   ; Indicates delegate to event or to-do
     ;Default is ATTENDEE

     statusparm = "STATUS" "="
                ("NEEDS-ACTION" ; Indicates event or to-do needs action
                / "ACCEPTED"    ; Indicates event or to-do accepted
                / "DECLINED"    ; Indicates event or to-do not accepted
                / "TENTATIVE"   ; Indicates event or to-do tentatively
                ; accepted. Status MAY change in the future.
                / "COMPLETED"   ; Indicates to-do was completed.
                ; COMPLETED property has date/time completed.
                / "IN-PROCESS"  ;Indicates to-do is in the process of
                ; being completed.
                / "DELEGATED"   ; Indicateds Indicates event or to-do delegated
                ; to another ATTENDEE
                / "CANCELLED")  ; Indicates event or to-do cancelled for
                                ; ATTENDEE
     ;Default is NEEDS-ACTION

     rsvpparm   = "RSVP" "="
                  ("TRUE"               ; Indicates response requested
                / "FALSE")              ; Indicates no response needed
     ;Default is FALSE

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     expectparm = "EXPECT" "="
                ("FYI"          ; Indicates request is for your info
                / "REQUIRE"     ; Indicates presence is required
                / "REQUEST")    ; Indicates presence is requested
     ;Default is FYI

     memberparm = "MEMBER" "=" cal-address *("," [WSP] cal-address)
     ; Indicates a group or mailing list

     deletoparm = "DELEGATED-TO" "=" cal-address *("," [WSP]
                  cal-address)
     ; Indicates who the request is delegated to

     delefromparm = "DELEGATED-FROM" "=" cal-address *("," [WSP]
                    cal-address)
     ;Indicates who the request is delegated from

   The following are examples of this property’s property's use for a to-do:

     ATTENDEE;ROLE=OWNER;STATUS=COMPLETED:jsmith@host1.com
     ATTENDEE;MEMBER=DEV-GROUP@host2.com:joecool@host2.com
     ATTENDEE;DELEGATED-FROM=immud@host3.com:ildoit@host1.com

     ATTENDEE;ROLE=OWNER;STATUS=COMPLETED: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:

     ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:John

     ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED: MAILTO:John Smith
      <jsmith@host1.com>
     ATTENDEE;ROLE=ATTENDEE;STATUS=TENTATIVE:Henry
     ATTENDEE;ROLE=ATTENDEE;STATUS=TENTATIVE:MAILTO:Henry Cabot

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      <hcabot@host2.com>
     ATTENDEE;ROLE=DELEGATE;STATUS=ACCEPTED:Jane
     ATTENDEE;ROLE=DELEGATE;STATUS=ACCEPTED:MAILTOJane Doe
      <jdoe@host1.com>

   The following is an example of this property with the value specified
   as an URL URI reference to a vCard that contains the information about
   the attendee:

     ATTENDEE;ROLE=ATTENDEE;STATUS=ACCEPTED;VALUE=URL:

     ATTENDEE;ROLE=ATTENDEE;STATUS=ACCEPTED;VALUE=URI:
      http://www.xyz.com/~myvcard.vcf

   The following is an example of this property with "delegatee"
   and"delegator" and
   "delegator" information for an event:

     ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:John

     ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:MAILTO:John Smith
      <jsmith@host1.com>

     ATTENDEE;ROLE=DELEGATE;STATUS=TENTATIVE;DELEGATED-FROM=
      iamboss@host2.com:Henry
      "MAILTO:iamboss@host2.com":MAILTO:Henry Cabot<hcabot@host2.com>

     ATTENDEE;ROLE=ATTENDEE;STATUS=DELEGATED;DELEGATED-TO=
      hcabot@host2.com=iamboss(The
      "MAILTO:hcabot@host2.com:MAILTO:iamboss(The Big Cheese)@host2.com
     ATTENDEE;ROLE=DELEGATE;STATUS=ACCEPTED:Jane

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     ATTENDEE;ROLE=DELEGATE;STATUS=ACCEPTED:MAILTO:Jane Doe
      <jdoe@host1.com>

   The default data type for this property is CAL-ADDRESS. The data type
   MAY be reset to URL; URI; in which case the value is a location or message
   that contains the information that is to be used to specify the
   attendee address.

4.6.3   Categories

   This property is identified by the property name CATEGORIES. This
   property defines the categories for a calendar component. The
   property MAY be specified within the "VEVENT", "VTODO" or "VJOURNAL"
   calendar component with an arbitrary text value. In the "VALARM"
   calendar component the property MUST be specified to declare the
   alarm category. More than one category MAY be specified as a list of
   categories separated by the COMMA character (ASCII decimal 44).

   The properties is defined by the following notation:

     categories = "CATEGORIES" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP]
                  catvalue CRLF

     catvalue   = cat1value *["," [ws] [WSP] cat1value]
                / cat2value *["," [ws] [WSP] cat2value]

     cat1value  = "ANNIVERSARY" / "APPOINTMENT" / "BUSINESS"
                / "EDUCATION" / "HOLIDAY" / "MEETING" / "MISCELLANEOUS"
                / "NON-WORKING HOURS" / "NOT IN OFFICE" / "PERSONAL"
                / "PHONE CALL"  / "SICK DAY" / "SPECIAL OCCASION"
                / "TRAVEL" / "VACATION" / word
     ;Used only in "VEVENT", "VTODO" and "VJOURNAL" calendar components.

     cat2value  = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE"
                / x-token iana-token / iana-word x-name
     ;Used only in "VALARM" calendar component.

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   The following are examples of this property in a "VEVENT", "VTODO" or
   "VJOURNAL" calendar component:

     CATEGORIES:APPOINTMENT,EDUCATION

     CATEGORIES:MEETING

   The following are examples of this property in a "VALARM" calendar
   component:

     CATEGORIES:AUDIO,DISPLAY

     CATEGORIES:PROCEDURE

   The data type for this property is TEXT.

Dawson/Stenerson                   43                  Expires MAY 1998

4.6.4   Classification

   This property is identified by the property name CLASS. This property
   defines the access classification for a calendar component. The
   property MAY only be specified in a "VEVENT", "VTODO" or "VJOURNAL"
   calendar component. The property MAY only be specified once.

   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 can not cannot be completely defined by this memo
   alone. Additionally, due to the "blind" nature of most exchange
   processes using this memo, these access classifications can not cannot serve
   as an enforcement statement for a system receiving an iCalendar
   object .
   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.

   The property is defined by the following notation:

     class      = "CLASS" [";" [ws] paramlist] ":" [ws] [WSP] classvalue CRLF

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

   The following is an example of this property:

     CLASS:PUBLIC

   The data type for this property is TEXT.

Dawson/Stenerson                   42                  Expires MAY 1998

4.6.5   Comment

   This property is identified by the property name COMMENT. This
   property specifies non-processing information intended to provide a
   comment to the calendar user. The property MAY be specified in any of
   the calendar components. The property MAY be specified multiple
   times.

   The property is defined by the following notation:

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

   The following is an example of this property:

     COMMENT:The meeting really needs to include both ourselves
       and the customer.  We can’t can't hold this  meeting without them

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       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.

4.6.6   Contact

   This property is defined by the property name CONTACT. The property
   is used to represent contact information or alternately a reference
   to contact information associated with the calendar component. The
   property MAY only be specified in the "VEVENT", "VTODO" and
   "VJOURNAL" calendar components. The property value consists of
   textual contact information. Alternately, the value type for the
   property can be reset such that the property references the URL URI to
   the contact information.

   The property is defined by the following notation:

     contact    = "CONTACT" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP]
                  text / url uri CRLF

   The following is an example of this property referencing textual
   contact information:

     CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

   The following is an example of this property referencing a LDAP URL URI
   to a directory entry containing the contact information:

   CONTACT;VALUE=URL:"ldap://host.com:6666/o=3DABC%20Industries,
     c=3DUS??(cn=3DBJim%20Dolittle)"

   CONTACT;VALUE=URI:ldap://host.com:6666/o=3DABC%20Industries\,
     c=3DUS??(cn=3DBJim%20Dolittle)

   The following is an example of this property referencing a MIME body
   part containing the contact information, such as a vCard embedded in
   a [MIME-DIR] content-type:

     CONTACT;VALUE=URL:<part3.msg970930T083000SILVER@host.com>

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     CONTACT;VALUE=URI:<part3.msg970930T083000SILVER@host.com>

   The default data type for this property is TEXT. The data type MAY be
   reset to URL URI in order to specify a reference to the contact
   information.

4.6.7   Date/Time Completed

   This property is identified by the property name COMPLETED. This
   property defines the date and time that a to-do was actually
   completed. The property MAY be specified once in a "VTODO" component.
   The date and time is an UTC value.

   The property is defined by the following notation:

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

   The following is an example of this property:

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     COMPLETED:19960401T235959Z

   The data type for this property is DATE-TIME.

4.6.8   Date/Time Created

   This property is identified by the property name CREATED. This
   property specifies the date and time that the calendar information
   was created by the Organizer. The property MAY be specified in any of
   the calendar components. The property MAY only be specified once. The
   date and time is an UTC value.

   The property is defined by the following notation:

     created    = "CREATED" ":" [ws] [WSP] date-time CRLF

   The following is an example of this property:

     CREATED:19960329T133000Z

   The data type for this property is DATE-TIME.

4.6.9   Date/Time Due

   This property is identified by the property name DUE. This property
   defines the date and time that a to-do is expected to be completed.
   The time can either be in local time, local time with UTC offset or
   UTC time. The property MAY only be specified in a "VTODO" calendar
   component and only once. The value MUST be a date/time after the
   DTSTART value, if specified.

   The property is defined by the following notation:

     due        = "DUE" ":" [ws] [WSP] date-time CRLF

   The following is an example of this property:

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     DUE:19960401T235959Z

   The type for this property is DATE-TIME.

4.6.10  Date/Time End

   This property is identified by the property name DTEND. This property
   MAY be specified within the "VEVENT", "VFREEBUSY", and "VTIMEZONE"
   calendar components.

   Within the "VEVENT" calendar component, this property defines the end
   date and time for the event. The property is REQUIRED in "VEVENT"
   calendar components. The time can either be in local time, local time
   with UTC offset or UTC time. The local time is only to be used to
   specify date and time values that do not need to be fixed. A
   recipient MUST assume their own time zone for data and time values

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   that do not include time zone information. 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 in local time with UTC offset or UTC time. The
   value MUST be later in time than the value of the "DTSTART" property.

   The property is defined by the following notation:

     dtend      = "DTEND" ":" [ws] [WSP] date-time CRLF

   The following is an example of this property:

     DTEND:19960401T235959Z

   The data type for this property is DATE-TIME.

4.6.11  Date/Time Stamp

   This property is identified by the property name DTSTAMP. This
   property specifies an UTC date/time stamp. The property indicates the
   date/time that the iCalendar object instance was created. This
   property MUST be included in "VEVENT", "VTODO", "VJOURNAL" and
   "VFREEBUSY" calendar components to permit the recipient to know when
   the iCalendar object was created.

   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.

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   The property is defined by the following notation:

     dtstamp    = "DTSTAMP" ":" [ws] [WSP] date-time CRLF

   The value type for this property is DATE-TIME. The value MUST be a
   UTC date/time value.

4.6.12  Date/Time Start

   This property is identified by the property name DTSTART. This
   property MAY be specified within the "VEVENT", "VTODO", "VFREEBUSY",
   and "VTIMEZONE" calendar components.

   Within the "VEVENT" calendar component, this property defines the
   start date and time for the event. The property is REQUIRED in
   "VEVENT" calendar components. The time can either be in local time,

Dawson/Stenerson                   47                  Expires MAY 1998
   local time with UTC offset or UTC time. The local time is only to be
   used to specify date and time values that do not need to be fixed. A
   recipient MUST assume their own time zone for data and time values
   that do not include time zone information. Events MAY 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 local time with UTC offset or 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 "VTIMEZONE" calendar components. The time
   MUST be specified as a UTC time.

   The property is defined by the following notation:

     dtstart    = "DTSTART" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP] (date-time
                / date) CRLF

   The following is an example of this property:

     DTSTART:19960401T235959-0600

   The default data type for this property is DATE-TIME. The data type
   MAY be overridden to be DATE.

4.6.13  Daylight

   This property is identified by the property name DAYLIGHT. This
   property MAY only be specified in a "VTIMEZONE" calendar component.
   This property specifies whether Daylight Saving Time (i.e., value is
   TRUE) or Standard Time (i.e., value is FALSE) is in effect for the
   time zone. The default value is FALSE or Standard Time.

   The property is defined by the following notation:

Dawson/Stenerson                   46                  Expires MAY 1998

     daylight   = "DAYLIGHT" ":" [ws] [WSP] boolean CRLF
     ;Default value is FALSE

   The following is an example of this property:

     DAYLIGHT:TRUE              ;Specifies DST in effect in time zone

   The data type for this property is BOOLEAN.

4.6.14  Description

   This property is identified by the property name DESCRIPTION. This
   property provides a more complete description of the calendar
   component, than that provided by the "SUMMARY" property. The property
   MAY be specified in the "VEVENT", "VTODO" and "VJOURNAL" calendar

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   components. The property MAY be specified multiple times only within
   a "VJOURNAL" calendar component.

   The property is defined by the following notation:

     Description

     description        = "DESCRIPTION" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP]
                          text CRLF

   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 editor's proof today.

   The data type for this property is TEXT.

4.6.15  Duration

   This property is identified by the property name DURATION. The
   property specifies a duration of time. The property MAY be specified
   in a "VEVENT" calendar component in order to specify a duration of
   the event, instead of an explicit end date/time. The property MAY be
   specified in a "VTODO" calendar component in order to specify a
   duration for the to-do. The property MAY be specified in a
   "VFREEBUSY" calendar component in order to specify the amount of free
   time being requested. The property MAY be specified in an "VALARM"
   calendar component in order to specify the period between repeating
   alarms.

   The property is defined by the following notation:

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     duration   = "DURATION" ":" [ws] [WSP] duration CRLF

   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

   The data type for this property is DURATION.

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4.6.16  Exception Date/Times

   This property is identified by the property name EXDATE. This
   property defines the list of date/time exceptions for a recurring
   "VEVENT", "VTODO" or "VJOURNAL" calendar component. The times can
   either be in local time, local time with UTC offset or UTC time.

   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 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 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 "EXDATE" property MAY 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".

   The property is defined by the following notation:

     exdate     = "EXDATE" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP] [date-time /
                  date] *("," [ws] [WSP] date-time/date) CRLF
     ;Values MUST match the specified value type.

   The following is an example of this property:

     EXDATE:19960402T010000Z,19960403T010000Z,19960404T010000Z

   The data type for this property is DATE-TIME. The data type MAY be
   reset to DATE.

Dawson/Stenerson                   48                  Expires MAY 1998

4.6.17  Exception Rule

   This property is identified by the property name EXRULE. This
   property defines a rule or repeating pattern for an exception to a
   recurrence set. This property MAY only be specified in the "VEVENT",
   "VTODO" or "VJOURNAL" calendar components.

   The exception rule, if specified, is used in computing the recurrence
   set. The recurrence set is the complete set of recurrence instances

Dawson/Stenerson                   50                  Expires MAY 1998
   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 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 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".

   The property is defined by the following notation:

     exrule     = "EXRULE" [";" [ws] paramlist] ":" [ws] [WSP] recur CRLF

   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.

4.6.18  Free/Busy Time

   This property is identified by the property name FREEBUSY. The
   property defines one or more free or busy time intervals. These time
   periods MAY be specified as either a start and end date-time or a
   start date-time and duration.

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   The date and time is either local time with UTC offset or a UTC
   value.

   The "FREEBUSY" property MAY include the "TYPE" property parameter to
   specify whether the information defines a free or busy time interval.

Dawson/Stenerson                   51                  Expires MAY 1998
   The default "TYPE" property parameter value is BUSY. The property MAY
   also include the "STATUS" 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 - - or busy time that has been tentatively
   scheduled. The default "STATUS" property parameter value is BUSY. The
   property is defined by the following notation:

     freebusy   = "FREEBUSY" *(";" [WSP] parameter) [";" [ws] paramlist] [";" [ws] [WSP]
                  fbparmlist] ":" [ws] [WSP] fbvalue CRLF

     fbparmlist = fbparam *(";" [ws] [WSP] fbparam)

     fbparam    = fbtype / fbstatus

     fbtype     = "TYPE" "=" ("FREE" or "BUSY")
     ;Default is BUSY

     fbstatus   = "STATUS" "="
                  "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 tentatively
                                ;scheduled interval.
     ;Default is BUSY

     fbvalue    = period *["," [ws] [WSP] period]
     ;Value MUST match default or explicit data type

   The following are some examples of this property:

     FREEBUSY;STATUS=UNAVAILABLE:19970308T160000Z/PT8H30M

     FREEBUSY;TYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H

   "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 specify more than one value, separated by
   the COMMA character (ASCII decimal 44). In such cases, the "FREEBUSY"
   property values should all be of the same "STATUS" property parameter
   type (e.g., all values of a particular "STATUS" listed together in a
   single property).

   The data type for this property is PERIOD.

Dawson/Stenerson                   50                  Expires MAY 1998

4.6.19  Geographic Position

   This property is identified by the property name GEO. This property
   specifies information related to the global position for a "VEVENT"
   or "VTODO" calendar component. The property value specifies latitude
   and longitude, in that order (i.e., "LAT LON" ordering). The

Dawson/Stenerson                   52                  Expires MAY 1998
   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.

   The property is defined by the following notation:

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

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

   The following is an example of this property:

     GEO:37.386013;-122.082932

   The default data type for this property is FLOAT.

4.6.20  Last Modified

   This property is identified by the property name LAST-MODIFIED. The
   property specifies the date and time that the calendar information
   was last revised. This property MAY be specified in the "VEVENT",
   "VTODO", "VJOURNAL" or "VFREEBUSY" calendar components. The data and
   time MUST be a UTC value.

   The property is defined by the following notation:

     last-mod   = "LAST-MODIFIED" ":" [ws] [WSP] date-time CRLF

   The following is are examples of this property:

     LAST-MODIFIED:19960817T133000Z

   The data type for this property is DATE-TIME.

4.6.21  Location

   This property is identified by the property name LOCATION. The
   property defines the intended location for the "VEVENT" or "VTODO"

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   calendar component. The property MAY only be specified within a
   "VEVENT" or "VTODO" calendar component.

   The property is defined by the following notation:

     location   = "LOCATION [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP] locavalue
                  CRLF

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     locavalue  = text / url uri    ;The value MUST be the same type as the
                                ;default or explicit data type.

   The following are some examples of this property:

     LOCATION:Conference Room - F123, Bldg. 002

     LOCATION;VALUE=URL:http://www.xyzcorp.com/~jsmith.vcf

     LOCATION;VALUE=URI:http://www.xyzcorp.com/~jsmith.vcf

   The default data type for this property is TEXT. The data type MAY be
   reset to URL. URI. In the case of the data type being URL, URI, the property
   value MAY reference a vCard object. This provides a useful mechanism
   to specify a location in terms of its electronic business card.

4.6.22  Percent Complete

   This property is identified by the property name PERCENT-COMPLETE.
   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. The
   property MAY only be specified once and within a "VTODO" calendar
   component. The property value is an 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.

   The property is defined by the following notation:

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

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

     PERCENT-COMPLETE:39

   The data type for this property is INTEGER.

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4.6.23  Priority

   This property is identified by the property name PRIORITY. The
   property defines the priority for event or to-do. The property MAY
   only be specified within a "VEVENT" or "VTODO" calendar component.
   The value is an integer. A value of zero (ASCII decimal 48) specifies
   an undefined priority. A value of one (ASCII decimal 49) is the
   highest priority. A value of two (ASCII decimal 50) is the second
   highest priority. Subsequent numbers specify a decreasing ordinal
   priority.

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   The property is specified by the following notation:

     priority   = "PRIORITY" ":" [ws] [WSP] integer CRLF
     ;Default is zero

   The following is an example of this property:

     PRIORITY:2

   The data type for this property is INTEGER.

4.6.24  Recurrence Date/Times

   This property is identified by the property name RDATE. This property
   defines the list of date/times for a recurrence set. The property MAY
   only appear within the "VEVENT", "VTODO", "VJOURNAL" or "VTIMEZONE"
   calendar components. This property MAY 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 times can either be in local time, local time with UTC
   offset or UTC based time. If local time is used, the "VTIMEZONE"
   calendar component MUST be included in the iCalendar object,
   otherwise the local time value will be interpreted relative to the
   time zone of the recipient. The period values for "RDATE" property
   are specified using a specific start and a specific end basic format
   (period-explicit) or the period with a specific start and a specific
   duration basic format (period-start).

   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 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

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   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 property is defined by the following notation:

     rdate      = "RDATE" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP] rdvalue
                  *("," [ws] [WSP] rdvalue) CRLF

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     rdvalue    = date-time / date / period
     ;Value MUST match the specified data type

   The following are examples of this property:

     RDATE:19970714T083000-0400

     RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z,
      19960404T010000Z/PT3H

     RDATE;VALUE=DATE:19970101,19970120,19970217,19970421
      19970526,19970704,19970901,19971014,19971128,19971129,19971225

   The default data type for this property is DATE-TIME. The data type
   MAY be reset to DATE or PERIOD.

4.6.25  Recurrence ID

   This property is identified by the property name RECURRENCE-ID. This
   property identifies is used in conjunction with the "UID" 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.

   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.

   The time of day component for the value MUST be either an UTC or a
   local time with UTC offset time format, unless the original calendar
   object was expressed as a "floating" calendar object; that is in
   local time with no time zone calendar component specified. If the
   value of the "DTSTART" property is a DATE type value, then the value
   MUST be the calendar date for the recurrence instance.

   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"
   property to identify a particular instance of a recurring event, to-
   do or journal.

   The property is defined by the following notation:

     recurid    = "RECURRENCE-ID" *(";" [WSP] parameter)
                  [";" [ws] [WSP] rangeparm] [";" [ws]
                  paramlist] ":" [ws] [WSP] [date-time / date]

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        ;Value must match value type.

     rangeparm  = "RANGE" "=" ("THISANDPRIOR" / "THISANDFUTURE")

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   The default value for the range parameter is the single recurrence
   instance only.

   The following are examples of this property:

     RECURRENCE-ID:19960401T235959Z

     RECURRENCE-ID;RANGE=THISANDFUTURE:19960120T120000Z

   This default data type for this property is DATE-TIME. The data type
   MAY be reset to DATE.

4.6.26  Recurrence Rule

   This property is identified by the property name RRULE. This property
   defines a rule or repeating pattern for a recurring events, to-dos,
   or time zone definitions. The property MAY be specified in the
   "VEVENT", "VTODO", "VJOURNAL" or "VTIMEZONE" calendar components. The
   data type for this property is RECUR.

   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 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.

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   This property is defined by the following notation:

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     rrule      = "RRULE" [";" [ws] paramlist] ":" [ws] [WSP] recur CRLF

   Examples of this property include the following. All examples assume
   the Eastern United States time zone.

   Daily for 10 occurrences:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=DAILY;COUNT=10

     ==> (1997 9AM EDT)September 2-11

   Daily until 12/24/97:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=DAILY;UNTIL=19971224T000000Z

     ==> (1997 9AM EDT)September 2-30;October 1-25
         (1997 9AM EST)October 26-31;November 1-30;December 1-24 1-23

   Every other day - forever:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=DAILY;INTERVAL=2
     ==> (1997 9AM EDT)September2,4,6,8...24,26,28,30;
          October 2,4,6...20,22,24
         (1997 9AM EST)October 26,28,30;November 1,3,5,7...25,27,29;
          Dec 1,3,...

   Every 10 days, 5 occurrences:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5

     ==> (1997 9AM EDT)September 2,12,22;October 2,12

   Everyday in January, for 3 years:

     DTSTART:19980101T090000-0400
     RRULE:FREQ=YEARLY;UNTIL:20000131T090000-0400;BYMONTH=1;BYDAY=SU,
      MO,TU,WE,TH,FR,SA
     or
     RRULE:FREQ=DAILY;UNTIL:20000131T090000-0400;BYMONTH=1

     ==> (1998 9AM EDT)January 1-31
         (1999 9AM EDT)January 1-31
         (2000 9AM EDT)January 1-31

   Weekly for 10 occurrences

     DTSTART:19970902T090000-0400
     RRULE:FREQ=WEEKLY;COUNT=10

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     ==> (1997 9AM EDT)September 2,9,16,23,30;October 7,14,21

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         (1997 9AM EST)October 28;November 4

   Weekly until 12/24/94

     DTSTART:19970902T090000-0400
     RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z

     ==> (1997 9AM EDT)September 2,9,16,23,30;October 7,14,21
         (1997 9AM EST)October 28;November 4,11,18,25;
                       December 2,9,16,23,24 2,9,16,23

   Every other week - forever:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU

     ==> (1997 9AM EDT)September 2,16,30;October 14
         (1997 9AM EST)October 28;November 11,25;December 9,23
         (1998 9AM EST)January 6,20;February
     ...

   Weekly on Tuesday and Thursday for 5 weeks:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=WEEKLY;UNTIL=19971007T000000-0400;WKST=SU;BYDAY=TU,TH
     or
     RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH

     ==> (1997 9AM 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, but
   starting on Tuesday, 9/2/97:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000-0400;WKST=SU;
      BYDAY=MO,WE,FR
     ==> (1997 9AM EDT)September 2,3,5,15,17,19,29;October 1,3,13,15,17
         (1997 9AM EST)October 27,29,31;November 10,12,14,24,26,28;
                       December 8,10,12,22,24 8,10,12,22

   Every other week on Tuesday and Thursday, for 8 occurrences:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH

     ==> (1997 9AM EDT)September 2,4,16,18,30;October 2,14,16

   Monthly on the 1st Friday for ten occurrences:

     DTSTART:19970905T090000-0400
     RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR

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     ==> (1997 9AM EDT)September 5;October 3

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         (1997 9AM EST)November 7;Dec 5
         (1998 9AM EST)January 2;February 6;March 6;April 3
         (1998 9AM EDT)MAY 1;June 5

   Monthly on the 1st Friday until 12/24/94:

     DTSTART:19970905T090000-0400
     RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;BYDAY=1FR

     ==> (1997 9AM EDT)September 5;October 3
         (1997 9AM EST)November 7;December 5

   Every other month on the 1st and last Sunday of the month for 10
   occurrences:

     DTSTART:19970907T090000-0400
     RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU

     ==> (1997 9AM EDT)September 7,28
         (1997 9AM EST)November 2,30
         (1998 9AM EST)January 4,25;March 1,29
         (1998 9AM EDT)MAY 3,31

   Monthly on the second to last Monday of the month for 6 months:

     DTSTART:19970922T090000-0400
     RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO

     ==> (1997 9AM EDT)September 22;October 20
         (1997 9AM EST)November 17;December 22
         (1998 9AM EST)January 19;February 16

   Monthly on the third to the last day of the month, forever:

     DTSTART:19970928T090000-0400
     RRULE:FREQ=MONTHLY;BYMONTHDAY=-3

     ==> (1997 9AM EDT)September 28
         (1997 9AM EST)October 29;November 28;December 29
         (1998 9AM EDT)January EST)January 29;February 26
     ...

   Monthly on the 2nd and 15th of the month for 10 occurrences:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15

     ==> (1997 9AM EDT)September 2,15;October 2,15
         (1997 9AM EST)November 2,15;December 2,15
         (1998 9AM EST)January 2,15

   Monthly on the first and last day of the month for 10 occurrences:

     DTSTART:19970930T090000-0400

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     DTSTART:19970930T090000-0400
     RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1

     ==> (1997 9AM EDT)September 30;October 1
         (1997 9AM EST)October 31;November 1,30;December 1,31
         (1998 9AM EST)January 1,31;February 1

   Every 18 months on the 10th thru 15th of the month for 10
   occurrences:

     DTSTART:19970910T090000-0400
     RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;BYMONTHDAY=10,11,12,13,14,
      15

     ==> (1997 9AM EDT)September 10,11,12,13,14,15
         (1999 9AM EST)March 10,11,12,13

   Every Tuesday, every other month:

     DTSTART:19970902T090000-0400
     RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU

     ==> (1997 9AM EDT)September 2,9,16,23,30
         (1997 9AM EST)November 4,11,18,25
         (1998 9AM EST)January 6,13,20,27;March 3,10,17,24,31
     ...

   Yearly in June and July for 10 occurrences:

     DTSTART:19970610T090000-0400
     RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7

     ==> (1997 9AM EDT)June 10;July 10
         (1998 9AM EDT)June 10;July 10
         (1999 9AM EDT)June 10;July 10
         (2000 9AM EDT)June 10;July 10
         (2001 9AM 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:19970310T090000-0400
     RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;BYMONTH=1,2,3

     ==> (1997 9AM EST)March 10
         (1999 9AM EST)January 10;February 10;March 10
         (2001 9AM EST)January 10;February 10;March 10
         (2003 9AM EST)January 10;February 10;March 10

   Every 3rd year on the 1st, 100th and 200th day for 10 occurrences:

     DTSTART:19970101T090000-0400
     RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;BYYEARDAY=1,100,200

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     ==> (1997 9AM EST)January 1
         (1997 9AM EDT)April 10;July 19
         (2000 9AM EST)January 1
         (2000 9AM EDT)April 9;July 18
         (2003 9AM EST)January 1
         (2003 9AM EDT)April 10;July 19
         (2006 9AM EST)January 1

   Every 20th Monday of the year, forever:

     DTSTART:19970519T090000-0400
     RRULE:FREQ=YEARLY;BYDAY=20MO

     ==> (1997 9AM EDT)MAY 19
         (1998 9AM EDT)MAY 18
         (1999 9AM EDT)MAY 17
     ...

   Monday of Week No. 20, forever:

     DTSTART:19970512T090000-0400
     RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO

     ==> (1997 9AM EDT)MAY 12
         (1998 9AM EDT)MAY 11
         (1999 9AM EDT)MAY 17
     ...

   Every Thursday in March, forever:

     DTSTART:19970313T090000-0400
     RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH

     ==> (1997 9AM EST)March 13,20,27
         (1998 9AM EST)March 5,12,19,26
         (1999 9AM EST)March 4,11,18,25
     ...

   Every Thursday, but only during summer months, forever:

     DTSTART:19970605T090000-0400
     RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8

     ==> (1997 9AM EDT)June 5,12,19,26;July 3,10,17,24,31;
                       August 7,14,21,28
         (1998 9AM EDT)June 4,11,18,25;July 2,9,16,23,30;
                       August 6,13,20,27
         (1999 9AM EDT)June 3,10,17,24;July 1,8,15,22,29;
                       August 5,12,19,26
     ...

   Every Friday the 13th, forever:

     DTSTART:19970902T090000-0400

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     DTSTART:19970902T090000-0400
     EXDATE:19970902T090000-0400
     RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13

     ==> (1998 9AM EST)February 13;March 13;November 13
         (1999 9AM EDT)August 13
         (2000 9AM EDT)October 13
     ...

   The first Saturday that follows the first Sunday of the month,
   forever:

     DTSTART:19970913T090000-0400
     RRULE:FREQ=MONTHLY;BYDAY=SA;BYMONTHDAY=7,8,9,10,11,12,13

     ==> (1997 9AM EDT)September 13;October 11
         (1997 9AM EST)November 8;December 13
         (1998 9AM EST)January 10;February 7;March 7
         (1998 9AM EDT)April 11;MAY 9;June 13...
     ...

   Every four years, the first Tuesday after a Monday in November,
   forever (U.S. Presidential Election day):

     DTSTART:19961105T090000-0400
     RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;BYDAY=TU;BYMONTHDAY=2,3,4,
      5,6,7,8

     ==> (1996 9AM EST)November 5
         (2000 9AM EST)November 7
         (2004 9AM EST)November 2
     ...

   The 3rd instance into the month of one of Tuesday, Wednesday or
   Thursday, for the next 3 months:

     DTSTART:19970904T090000-0400
     RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;BYSETPOS=3

     ==> (1997 9AM EDT)September 4;October 7
         (1997 9AM EST)November 5 6

   The 2nd to last weekday of the month:

     DTSTART:19970929T090000-0400
     RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-2

     ==> (1997 9AM EDT)September 29
         (1997 9AM EST)October 30;November 27;December 30
         (1998 9AM EST)January 29;February 26;March 30
     ...

   Every 3 hours from 9AM to 5PM on a specific day:

     DTSTART:19970902T090000-0400

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     DTSTART:19970902T090000-0400
     RRULE:FREQ=HOURLY;INTERVAL=3;UNTIL=19970902T170000-0400

     ==> (September 2, 1997 EDT)09:00,12:00,15:00

   Every 15 minutes for 6 occurrences:

     DTSTART:19970902T090000-0400
     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:19970902T090000-0400
     RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4

     ==> (September 2, 1997 EDT)09:00,10:30;12:00;13:30

   Every 20 minutes from 9AM to 4:40PM every day:

     DTSTART:19970902T090000-0400
     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 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:19970805T090000-0400
     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 reults...

     DTSTART:19970805T090000-0400
     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU
     ==> (1997 EDT)August 5,17,19,31

4.6.27  Related To

   This property is identified by the property name RELATED-TO. The
   property is used to represent relationships a relationship or references reference between one
   calendar component and another. The property MAY only be specified
   once in the "VEVENT", "VTODO", "VJOURNAL" or "VFREEBUSY" calendar
   components. The property value consists of the persistent, globally
   unique

Dawson/Stenerson                   62                  Expires MAY 1998 identifier of another calendar component. This value would be
   represented in a calendar component by the "UID" property. The

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   By default, the property value always points to another calendar component
   that has a
   "parent" PARENT relationship to the referencing object.

   A linked The
   "RELTYPE" property parameter is used to either explicitly state the
   default PARENT relationship can be specified by type to the referenced calendar component
   or to override the default PARENT relationship type and specify
   either a series of components CHILD or SIBLING relationship. The PARENT relationship
   indicates that
   each, in turn, refer to their parent the calendar component is a subordinate of the
   referenced calendar component. A group The CHILD relationship
   can be specified by indicates that
   the calendar component is a number superior of components the referenced calendar
   component. The SIBLING relationship indicates that all refer to one
   common parent the calendar
   component is a peer of the referenced calendar component.

   Changes to a calendar component referenced by this property MAY have
   an implied impact to 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. 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.

   The property is defined by the following notation:

     related    = "RELATED-TO" [";" [ws] paramlist] [WSP] relparam) ":" [ws] [WSP] uid CRLF

     relparam   = "RELTYPE" "="
                  "PARENT"      ; Parent relationship. Default.
                / "CHILD"       ; Child relationship.
                / "SIBLING"     ; Sibling relationship.

   The following is an example of this property:

     RELATED-TO:<jsmith.part7.19960817T083000.xyzMail@host3.com>

     RELATED-TO:<19960401-080045-4000F192713-0052@host1.com>

   The data type for this property is UID.

4.6.28  Repeat Count

   This property is identified by the property name REPEAT. This
   property defines the number of repetitions for an alarm. time the alarm should be repeated,
   after the initial trigger.

   The property is defined by the following notation:

     repeatcnt  = "REPEAT" ":" [ws] [WSP] integer CRLF
     ;Default is "1". "0", zero.

   The following is an example of this property:

     REPEAT:4

   The data type for the property is INTEGER.

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4.6.29  Request Status

   This property is identified by the property name REQUEST-STATUS. This
   property defines the status code returned for a scheduling request.
   This property is used to return status code information related to

Dawson/Stenerson                   63                  Expires MAY 1998
   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 decimal 59).

   The short return status is a PERIOD character (ASCII decimal xx)
   separated set of integers. For example, "3.1.1". The successive
   levels of integers provide for a successive level of status code
   granularity.

   The property is defined by the following notation:

     Rstatus

     rstatus    = "REQUEST-STATUS" *(";" [WSP] parameter) ":" [ws] [WSP]
                  statcode ";" [ws] [WSP] statdesc [";" [ws] [WSP] extdata]

     Statcode

     statcode   = 1*DIGIT *("." 1*DIGIT)
     ;Hierarchical, numeric return status code

     Statdesc

     statdesc   = *WORD text
     ;Textual status description

     Extdata

     extdata    = *WORD text
     ;Textual exception data. For example, the offending property
     ;name and value or complete property line.

   The following are some possible examples of this property (Note: The
   BACKSLASH character escapement of separator characters in a property
   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\:
      jsmith@host.com user;ATTENDEE:
      MAILTO:jsmith@host.com

   The following are valid classes for the return status code.
   Individual iCalendar object methods will define specific return
   status codes for these classes.

     |==============+===============================================|
     | Short Return | Longer Return Status Description              |

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     | 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 |

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     |              | completion is pending.                        |
     |==============+===============================================|
     |    2.xx      | Successful. This class of status code         |
     |              | indicates that the request was completed      |
     |              | successfuly. However, the exact status code   |
     |              | MAY indicate that a fallback has been taken.  |
     |==============+===============================================|
     |    3.xx      | Client Error. This class of status code       |
     |              | 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.|
     |              | Some sort of error occurred within the        |
     |              | calendaring and scheduling service, not       |
     |              | directly related to the request itself.       |
     |==============+===============================================|

4.6.30  Resources

   This property is identified by the property name RESOURCES. This
   property defines the equipment or resources needed for the event or
   to-do. The property value is an arbitrary text. The property MAY only
   be specified in the "VEVENT" or "VTODO" calendar component. More than
   one resource MAY be specified as a list of resources separated by the
   COMMA character (ASCII decimal 44).

   The property is defined by the following notation:

     resource   = "RESOURCES" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP]
                  resvalist CRLF

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

     resvalue   = "CATERING" / "CHAIRS" / "COMPUTER PROJECTOR"
                / "EASEL" / "OVERHEAD PROJECTOR" / "SPEAKER PHONE"
                / "TABLE" / "TV" / "VCR" / "VIDEO PHONE" / "VEHICLE"
                / word

   The following is an example of this property:

     RESOURCES:EASEL,PROJECTOR,VCR

   The data type for this property is TEXT.

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4.6.31  Sequence Number

   This property is identified by the property name SEQUENCE. This
   property defines the revision sequence of the calendar component used
   in a request. The property MAY only be specified in a "VEVENT",

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   "VTODO", "VJOURNAL" or "VFREEBUSY" calendar component. This property
   is needed to properly handle the receipt and processing of 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 is
   created with a sequence number of "0" (ASCII decimal 48). It is
   incremented each time the ORGANIZER or OWNER issues a revision to the
   request. The sequence number MUST be monotonically incremented when
   one of the following properties in a calendar component is changed:

     ·

     .  "DTSTART"
     ·
     .  "DTEND"
     ·
     .  "DUE"
     ·
     .  "RDATE"
     ·
     .  "RRULE"
     ·
     .  "EXDATE"
     ·
     .  "EXRULE"

   The property is defined by the following notation:

     sequence   = "SEQUENCE" ":" [ws] [WSP] integer CRLF
     ;Default is "0".

   The following is an example of this property:

     SEQUENCE:1

   The data type for this property is INTEGER.

4.6.32  Status

   This property is identified by the property name STATUS. This
   property defines the orignator's view of the overall status for the
   calendar component. This property MAY only be specified in the
   "VEVENT", "VTODO", "VJOURNAL" calendar components. The property is
   used to specify the originator's view of the general consensus for
   the event or the to-do. In addition, when specified in a group
   scheduled to-do the property is used to specify the originator's view
   of the completion status for the to-do. The property MAY also specify
   whether the event or to-do has been cancelled.

   The property is defined by the following notation:

     status     = "STATUS" [";" [ws] paramlist] ":" [ws] [WSP] statvalue CRLF

     statvalue  = "NEEDS-ACTION"        ;Indicates to-do needs action.
                / "COMPLETED"           ;Indicates to-do completed.
                / "IN-PROCESS"          ;Indicates to-do in process of
                                        ;being completed.
                / "TENTATIVE"           ;Indicates event or to-do is

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                                        ;tentative.
                / "CONFIRMED"           ;Indicates event or to-do is
                                        ;definite.

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                / "CANCELLED"           ;Indicates event or to-do was
                                        ;cancelled.

   The following is an example of this property:

     STATUS:TENTATIVE

   The data type for this property is TEXT.

4.6.33  Summary

   This property is identified by the property name SUMMARY. This
   property defines a short summary or subject for the calendar
   component. The property MUST be specified in the "VEVENT", "VTODO"
   and "VJOURNAL" calendar components. In addition, it MAY appear in the
   "VALARM" calendar component.

   The property is defined by the following notation:

     summary    = "SUMMARY" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP] text CRLF

   The following is an example of this property:

     SUMMARY:Department Party

   The data type for this property is TEXT.

4.6.34  Time Transparency

   This property is identified by the property name TRANSP. This
   property defines whether an event is transparent or not to busy time
   searches. This property MAY only be specified in a "VEVENT" calendar
   component.

   The property is specified by the following notation:

     transp     = "TRANSP" [";" [ws] paramlist] ":" [ws] [WSP] transvalue CRLF

     transvalue = "OPAQUE"      ;Blocks or opaque on busy time searches.
                / "TRANSPARENT" ;Transparent on busy time searches.

        ;Default value is OPAQUE

   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

Dawson/Stenerson                   67                   69                  Expires MAY 1998
     TRANSP:OPAQUE

   The data type for this property is TEXT.

4.6.35  Time Zone Name

   This property is identified by the property name TZNAME. This
   property specifies the customary designation for a time zone
   description. This property MAY only be specified in the "VTIMEZONE"
   calendar component.

   This property is defined by the following notation:

     tzname     = "TZNAME" [";" [ws] paramlist] *(";" [WSP] parameter) ":" [ws] [WSP] text CRLF

   The following are examples of this property:

     TZNAME: EST

     TZNAME: PDT

   The data type for this property is TEXT.

4.6.36  Time Zone Offset

   This property is identified by the property name TZOFFSET. This
   property specifies the offset from UTC for a time zone. This property
   MAY 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.

   The property is defined by the following notation:

     tzoffset   = "TZOFFSET" ":" [ws] [WSP] utc-offset CRLF

   The following are examples of this property:

     TZOFFSET:-0500

     TZOFFSET:+0530

   The data type for this property is UTC-OFFSET.

4.6.37  Uniform Resource Locator

   This property is identified by the property name URL. This property
   defines a Uniform Resource Locator (URL) associated with the
   iCalendar object. This property MAY be specified once in the
   "VEVENT", "VTODO", "VJOURNAL", "VFREEBUSY", "VJOURNAL" and "VALARM" "VFREEBUSY" calendar components.

   The property is defined by the following notation:

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     url        = "URL" ":" [ws] url [WSP] uri CRLF

   The following is an example of this property:

     URL:http://abc.com/pub/calendars/jsmith/mytime.or3

   The data type for this property is URL. URI.

4.6.38  Unique Identifier

   This property is identified by the property name UID. This property
   defines the persistent, globally unique identifier for the calendar
   component. The property MUST be specified in the "VEVENT", "VTODO"
   and "VTODO",
   "VJOURNAL" and "VFREEBUSY" calendar components.

   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
   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
   identifier can guarantee the uniqueness of the left hand side within
   the scope of that domain.

   This identifier is created by the calendar system that generates an
   iCalendar object. The identifier is represented as a text value. This is the method for correlating scheduling messages with the
   referenced
   event, to-do, "VEVENT", "VTODO", or journal. "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.

   The property is defined by the following notation:

     uid        = "UID" ":" [ws] [WSP] text CRLF

   The following is an example of this property:

     UID:19960401T080045Z-4000F192713-0052@host1.com

   This property is an important method for group scheduling
   applications to match requests with later replies, modifications or

Dawson/Stenerson                   71                  Expires MAY 1998
   deletion requests. Calendaring and scheduling applications MUST
   generate this property in "VEVENT", "VTODO" and "VJOURNAL" calendar

Dawson/Stenerson                   69                  Expires MAY 1998
   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.

   The data type for this property is TEXT.

4.6.39  Non-standard Properties

   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 ignore them.

   The property is defined by the following notation:

     extension  = "X-" [vendorid] "-" word [";" [ws] paramlist] *(";" [WSP] param) ":" [ws]
                  value
                  [WSP] value-list CRLF
        ; Lines longer than 75 characters should be folded

     vendorid   = 3*char        ;Vendor identification prefix text

   The following might be the ABC vendor’s vendor's extension for an audio-clip
   form of subject property:

     X-ABC-MMSUBJ;TYPE=WAVE; VALUE=URL:

     X-ABC-MMSUBJ;TYPE=wave; VALUE=URI: http://load.noise.org/mysubj.wav

   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 be any of the other valid data
   types.

5.      Recommended Practices

   These recommended practices should be followed in order to assure
   consistent handling of the following cases for an iCalendar object.

   1.      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

Dawson/Stenerson                   72                  Expires MAY 1998
     time, it MUST NOT be used to record busy time no matter what the
     value for the "TRANSP" property.

Dawson/Stenerson                   70                  Expires MAY 1998

   2.      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 specify values in the same time format
     (e.g., local time with UTC offset).

   3.      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.

   4.      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.      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.

6.1     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.

6.2     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 properties MAY 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.

6.2.1   Define the property

   A property is defined by completing the following template.

     To: ietf-calendar@imc.org

Dawson/Stenerson                   73                  Expires MAY 1998
     Subject: Registration of text/calendar MIME property XXX

Dawson/Stenerson                   71                  Expires MAY 1998

     Property name:

     Property purpose:

     Property data type(s):

     Property encoding:

     Property special notes (optional):

     Intended usage: (one of COMMON, LIMITED USE or OBSOLETE)

   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): Any of the valid data types for the property
   value needs to be specified. The default data type also needs to be
   specified. If a new data type is specified, it needs to be declared
   in this section.

   Property encoding: The encodings permitted for the property value.
   This description MUST be precise and MUST NOT violate the general
   encoding rules defined in this memo.

   Property special notes: Any special notes about the property, how it
   is to be used, etc.

6.2.2   Post the Property definition

   The property description MUST be posted to the new property
   discussion list, ietf-calendar@imc.org.

6.2.3   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.

6.2.4   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
   for approval. The Method Reviewer is appointed to the Application
   Area Directors and MAY either accept or reject the property
   registration. An accepted registration should be passed on by the

Dawson/Stenerson                   72                  Expires MAY 1998
   Method Reviewer to the IANA for inclusion in the official IANA method
   registry. The registration MAY be rejected for any of the following
   reasons. 1) Insufficient comment period; 2) Consensus not reached; 3)

Dawson/Stenerson                   74                  Expires MAY 1998
   Technical deficiencies raised on the list or elsewhere have not been
   addressed. The Method Reviewer's decision to reject a property MAY be
   appealed by the proposer to the IESG, or the objections raised can be
   addressed by the proposer and the property resubmitted.

6.3     Property Change Control

   Existing properties MAY 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
   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 object to a change if it
   is not backwards 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.

7.      File extension

   The file extension of "vcs" is to be used to designate a file
   containing calendaring and scheduling information consistent with
   this MIME content type.

8.      Macintosh File Type Code

   The file type code of "vcal" 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.

9.      References

   The following document are referred to within this memo.

   [ICMS] "Internet Calendaring Model Specification", Internet-Draft,
   July 1997, ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-mod-
   00.txt.

Dawson/Stenerson                   73                  Expires MAY 1998
   03.txt.

   [IMIP] "iCalendar Message-based Interoperability Protocol (IMIP)",
   Internet Draft, October 1997, http://www.imc.org/draft-ietf-calsch-
   imip-02.txt.
   imip-03.txt.

Dawson/Stenerson                   75                  Expires MAY 1998
   [ISO 8601] ISO 8601, "Data elements and interchange formats-                                                              -                                                               - formats_
   Information interchange--Representation of dates and times",
   International Organization for Standardization, June, 1988. This
   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 Technology_SGML Support
   Facilities--Registration Procedures for Public Text Owner
   Identifiers", Second Edition, International Organization for
   Standardization, April, 1991.

   [ITIP] "iCalendar Transport-Independent Interoperability Protocol
   (iTIP) : Scheduling Events, Busy Time, To-dos and Journal Entries ",
   Internet-Draft, October 1997, http://www.imc.org/draft-ietf-calsch-
   itip-01.txt.
   itip-02.txt.

   [MIME DIR] Howes, T., Smith, M., "A MIME Content-Type for Directory
   Information", Internet-draft-ietf-asid-mime-direct-06.txt, July, Internet-draft-ietf-asid-mime-direct-07.txt, 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.

   [RFC1983]

   [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.

   [RFC 2048] Freed, N., J. Klensin, J. Postel, "Multipurpose Internet
   Mail Extensions (MIME) - Part Four: Registration Procedures", RFC
   2048, January 1997.

Dawson/Stenerson                   74                  Expires MAY 1998
   [RFC2119]

   [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.

Dawson/Stenerson                   76                  Expires MAY 1998
   [UTF-8] "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.

   [VCARD] Internet Mail Consortium, "vCard - The Electronic Business
   Card Version 2.1", http://www.versit.com/pdi/vcard-21.txt, September
   18, 1996.

   [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.

10.     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, Bruce Kahn, C. Harald Koch, Ryan Jansen,
   Don Lavange, 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.

11.     Copyright

12.     Author's Address

   The following address information is provided in a MIME-VCARD,
   Electronic Business Card, format.

   The authors of this draft are:

     BEGIN:VCARD
     FN:Frank Dawson
     ORG:Lotus Development Corporation
     ADR;WORK;POSTAL;PARCEL:;;6544
     ADR;WORK;POSTAL;PARCEL:;6544 Battleford Drive;

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      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

Dawson/Stenerson                   77                  Expires MAY 1998
     BEGIN:VCARD
     FN:Derik Stenerson
     ORG:Microsoft Corporation
     ADR;WORK;POSTAL;PARCEL:;;One
     ADR;WORK;POSTAL;PARCEL:;One Microsoft Way;
      Redmond;WA;98052-6399;USA
     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
     FN:Anik Ganguly
     ORG:OnTime, Inc.
     ADR;WORK;POSTAL;PARCEL:10 Floor;;21700 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

13.

12.     iCalendar object Examples

   The following examples are provided as an informational source of
   illustrative iCalendar objects consistent with this content type.

   The following iCalendar object is specified as the content of a MIME
   message. The example demonstrates a possible meeting request between
   the originator and recipient of the message.

     TO:jsmith@host1.com
     FROM:jdoe@host1.com
     MIME-VERSION:1.0
     MESSAGE-ID:<id1@host1.com>
     CONTENT-TYPE:text/calendar;method=request

     BEGIN:VCALENDAR
     METHOD:REQUEST
     PRODID:-//xyz Corp//NONSGML PDA Calendar Verson 1.0//EN
     VERSION:2.0
     BEGIN:VEVENT

Dawson/Stenerson                   76                  Expires MAY 1998
     DTSTAMP:19960704T120000Z
     DTSTART:19960918T143000Z
     DTEND:19960920T220000Z
     CATEGORIES:CONFERENCE,PROJECT
     SUMMARY:Networld+Interop Conference
     DESCRIPTION:Networld+Interop Conference
       and Exhibit\nAtlanta World Congress Center\n
     Atlanta, Georgia

Dawson/Stenerson                   78                  Expires MAY 1998
     END:VEVENT
     END:VCALENDAR

   The following example message issues a meeting request that does not
   require any reply. The message is sent as a singular "text/calendar"
   content type, body part.

     From: jsmith@host1.com
     To: ietf-calendar@imc.org
     Subject: First IETF-Calendar Working Group Meeting
     MIME-Version: 1.0
     Message-ID: <id2@host1.com>
     Content-Type: text/calendar;method=request

     BEGIN:VCALENDAR
     METHOD:REQUEST
     PRODID:-//RDU Software//NONSGML HandCal//EN
     VERSION:2.0
     BEGIN:VEVENT
     DTSTAMP:19961022T133000Z
     ATTENDEE;EXPECT=REQUEST:ietf-calendar@imc.org
     ATTENDEE;EXPECT=REQUEST:MAILTO:ietf-calendar@imc.org
     DESCRIPTION:First IETF-Calendaring and Scheduling Working Group
       Meeting
     CATEGORIES:MEETING
     CLASS:PUBLIC
     CREATED:19961022T083000
     SUMMARY:IETF Calendaring Working Group Meeting
     DTSTART:19961210T210000Z
     DTEND:19961210T220000Z
     LOCATION:San Jose, CA - Fairmont Hotel
     UID:guid-1.host1.com
     END:VEVENT
     END:VCALENDAR

   The following is an example of a MIME message with a single body part
   consisting of a text/calendar content type. The message specifies a
   meeting request between the originator and recipient of the message.

     TO:jsmith@host1.com
     FROM:jdoe@host1.com
     MIME-VERSION:1.0
     MESSAGE-ID:<id3@host1.com>
     CONTENT-TYPE:text/calendar;method=request

Dawson/Stenerson                   77                  Expires MAY 1998

     BEGIN:VCALENDAR
     METHOD:REQUEST
     VERSION:2.0
     PRODID:-//ABC Corporation//NONSGML My Product//EN
     BEGIN:VEVENT
     DTSTAMP:19970324T1200Z
     SEQUENCE:0
     UID:19970324T080045Z-4000F192713-0052@host1.com
     ATTENDEE;EXPECT=REQUEST:jsmith@host1.com
     ATTENDEE;EXPECT=REQUEST:MAILTO:jsmith@host1.com
     DTSTART:19970324T123000Z

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     DTEND:19970324T210000Z
     CATEGORIES:CONFERENCE,PROJECT
     CLASS:PUBLIC
     SUMMARY:Calendaring Interop Conference
     DESCRIPTION:Calendaring Interop Conference and Exhibit\n
      Atlanta, Georgia
     LOCATION:Atlanta World Congress Center
     ATTACH;VALUE=URL:file:///xyzCorp.com/conf/bkgrnd.ps
     ATTACH;VALUE=URI:file:///xyzCorp.com/conf/bkgrnd.ps
     END:VEVENT
     END:VCALENDAR

   Example of a reply to the above request, accepting the meeting.

     TO:jdoe@host1.com
     FROM:jsmith@host1.com
     MIME-VERSION:1.0
     MESSAGE-ID:<id4@host1.com>
     CONTENT-TYPE:text/calendar;method=reply

     BEGIN:VCALENDAR
     METHOD:REPLY
     VERSION:2.0
     PRODID:-//ABC Corporation//NONSGML My Product//EN
     BEGIN:VEVENT
     DTSTAMP:19970324T120000Z
     SEQUENCE:0
     UID:19970324T080045Z-4000F192713-0052@host1.com
     ATTENDEE;STATUS=ACCEPTED;EXPECT=REQUEST:jsmith@host1.com
     ATTENDEE;STATUS=ACCEPTED;EXPECT=REQUEST:MAILTO:jsmith@host1.com
     END:VEVENT
     END:VCALENDAR

   An example of a meeting cancelation:

     TO:jsmith@host1.com
     FROM:jdoe@host1.com
     MIME-VERSION:1.0
     MESSAGE-ID:<id5@host1.com>
     CONTENT-TYPE:text/calendar;method=cancel

     BEGIN:VCALENDAR
     METHOD:CANCEL
     VERSION:2.0
     PRODID:-//ABC Corporation//NONSGML My Product//EN
     BEGIN:VEVENT

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     DTSTAMP:19970324T120000Z
     UID:19970324T080045Z-4000F192713-0052@host1.com
     END:VEVENT
     END:VCALENDAR

14.

13.     Full Copyright Statement

   "Copyright (C) The Internet Society (date).  All Rights Reserved.

Dawson/Stenerson                   80                  Expires MAY 1998
   This document and translations of it MAY be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implmentation 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 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
   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                   79                   81                  Expires MAY 1998