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Versions: 00 01 02 03 04 05 06 07 RFC 2447

Network Working Group                                Frank Dawson/Lotus
Internet Draft                                   Steve Mansour/Netscape
<draft-ietf-calsch-imip-07.txt>              Steve Silverberg/Microsoft
Expires six months after                             September 15, 1998


           iCalendar Message-Based Interoperability Protocol
                                 (iMIP)


Status of this Memo
This document 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 ftp.ietf.org (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).

Distribution of this document is unlimited.



Abstract
This document, [iMIP], specifies a binding from the iCalendar Transport-
independent Interoperability Protocol (iTIP) to Internet email-based
transports. Calendaring entries defined by the iCalendar Object Model
[iCAL] are composed using constructs from [RFC-822], [RFC-2045], [RFC-
2046], [RFC-2047], [RFC-2048] and [RFC-2049].

This document is based on the calendaring and scheduling model defined
by [ICMS].

This document is based on discussions within the Internet Engineering
Task Force (IETF) Calendaring and Scheduling (CALSCH) working group.
More information about the IETF CALSCH working group activities can be
found on the IMC web site at http://www.imc.org, the IETF web site at
http://www.ietf.org/html.charters/calsch-charter.html. Refer to the
references within this document for further information on how to access
these various documents.

Distribution of this document is unlimited. Comments and suggestions for
improvement should be sent to the authors.



Copyright (C) The Internet Society 1998. All Rights Reserved.




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Table of Contents

1 INTRODUCTION.........................................................3

 1.1 RELATED MEMOS ....................................................3
 1.2 FORMATTING CONVENTIONS ...........................................3
 1.3 TERMINOLOGY ......................................................4

2 MIME MESSAGE FORMAT BINDING..........................................4

 2.1 MIME MEDIA TYPE ..................................................4
 2.2 SECURITY .........................................................4
   2.2.1 Authorization ................................................5
   2.2.2 Authentication ...............................................5
   2.2.3 Confidentiality ..............................................5
 2.3 [RFC-822] ADDRESSES ..............................................5
 2.4 CONTENT TYPE .....................................................6
 2.5 CONTENT-TRANSFER-ENCODING ........................................7
 2.6 CONTENT-DISPOSITION ..............................................7

3 SECURITY CONSIDERATIONS..............................................7


4 EXAMPLES.............................................................8

 4.1 SINGLE COMPONENT WITH AN ATTACH PROPERTY .........................8
 4.2 USING MULTIPART ALTERNATIVE FOR LOW FIDELITY CLIENTS .............8
 4.3 SINGLE COMPONENT WITH AN ATTACH PROPERTY AND INLINE ATTACHMENT ...9
 4.4 MULTIPLE SIMILAR COMPONENTS .....................................10
 4.5 MULTIPLE MIXED COMPONENTS .......................................11
 4.6 DETAILED COMPONENTS WITH AN ATTACH PROPERTY .....................12

5 RECOMMENDED PRACTICES...............................................14

 5.1 USE OF CONTENT AND MESSAGE IDS ..................................14

6 BIBLIOGRAPHY........................................................14


7 AUTHORS ADDRESSES...................................................15


8 FULL COPYRIGHT STATEMENT............................................16











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1  Introduction

This binding document provides the transport specific information
necessary convey iCalendar Transport-independent Interoperability
Protocol (iTIP) over MIME as defined in [RFC-822] and [RFC-2045].


1.1 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 document, [iMIP], specifies an Internet email binding for iTIP.

[ICMS] - specifies a common terminology and abstract;

[iCAL] - specifies a core specification of objects, data types,
properties and property parameters;

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

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.


1.2 Formatting Conventions

The mechanisms defined in this memo are defined in prose. In order to
refer to elements of the calendaring and scheduling model, core object
or interoperability protocol defined in [ICMS], [iCAL] and [iTIP] some
formatting conventions have been used.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this
document are to be interpreted as described in [RFC-2119].

Calendaring and scheduling roles described 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 [iCAL] 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.



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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.

Properties defined by [iCAL] 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 [iCAL] 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.


1.3 Terminology

The email terms used in this memo are defined in [RFC-822] and [RFC-
2045]. The calendaring and scheduling terms used in this memo are
defined in [ICMS], [iCAL] and [iTIP].


2  MIME Message Format Binding

This section defines the message binding to the MIME electronic mail
transport.

The sections below refer to the "originator" and the "respondent" of an
iMIP message. Typically, the originator is the "Organizer" of an event.
The respondent is an "Attendee" of the event.

The [RFC-822] "Reply-To" header typically contains the email address of
the originator or respondent of an event. However, this cannot be
guaranteed as Mail User Agents (MUA) are not required to enforce iMIP
semantics.


2.1 MIME Media Type

A MIME entity containing content information formatted according to this
document will be referenced as a "text/calendar" content type. It is
assumed that this content type will be transported through a MIME
electronic mail transport.


2.2 Security

This section addresses several aspects of security including
Authentication, Authorization and Confidentiality. Authentication and
confidentiality can be achieved using [RFC-1847] that specifies the
Security Multiparts for MIME. This framework defines new content types
and subtypes of multipart: signed and encrypted. Each contains two body


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parts: one for the protected data and another for the control
information necessary to remove the protection.


2.2.1     Authorization

In [iTIP] messages, only the "Organizer" is authorized to modify or
cancel calendar entries they organize. That is, spoof@xyz.com is not
allowed to modify or cancel a meeting that was organized by
a@example.com. Furthermore, only the respondent has the authorization to
indicate their status to the "Organizer". That is, the "Organizer" must
ignore an [iTIP] message from spoof@xyz.com that declines a meeting
invitation for b@example.com.

Implementations of iMIP SHOULD verify the authenticity of the creator of
an iCalendar object before taking any action. The methods for doing this
are presented later in this document.

[RFC-1847] Message flow in iTIP supports someone working on behalf of a
"Calendar User" through use of the "sent-by" parameter that is
associated with the "ATTENDEE" and "ORGANIZER" properties. However,
there is no mechanism to verify whether or not a "Calendar User" has
authorized someone to work on their behalf. It is left to
implementations to provide mechanisms for the "Calendar Users" to make
that decision.


2.2.2     Authentication

Authentication can be performed using an implementation of [RFC-1847]
"multipart/signed" that supports public/private key certificates.
Authentication is possible only on messages that have been signed.
Authenticating an unsigned message may not be reliable.


2.2.3     Confidentiality

To ensure confidentiality using iMIP implementations should utilize
[RFC-1847]-compliant encryption. The protocol does not restrict a
"Calendar User Agent" (CUA) from forwarding iCalendar objects to other
users or agents.


2.3 [RFC-822] Addresses

The calendar address specified within the "ATTENDEE" property in an
iCalendar object MUST be a fully qualified, [RFC-822] address
specification for the corresponding "Organizer" or "Attendee" of the
"VEVENT" or "VTODO".

Because [iTIP] does not preclude "Attendees" from forwarding "VEVENTS"
or "VTODOS" to others, the [RFC-822] "Sender" value may not equal that
of the "Organizer". Additionally, the "Organizer" or  "Attendee" cannot
be reliably inferred by the [RFC-822] "Sender" or "Reply-to" values of


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an iMIP message.  The relevant address MUST be ascertained by opening
the "text/calendar" MIME body part and examining the "ATTENDEE" and
"ORGANIZER" properties.


2.4 Content Type

A MIME body part containing content information that conforms to this
document MUST have an [RFC-2045] "Content-Type" value of
"text/calendar". The [RFC-2045] "Content-Type" header field must also
include the type parameter "method". The value MUST be the same as the
value of the "METHOD" calendar property within the iCalendar object.
This means that a MIME message containing multiple iCalendar objects
with different method values must be further encapsulated with a
"multipart/mixed" MIME entity. This will allow each of the iCalendar
objects to be encapsulated within their own "text/calendar" MIME entity.

A "charset" parameter MUST be present if the iCalendar object contains
characters that are not part of the US-ASCII character set. [RFC-2046]
discusses the selection of an appropriate "charset" value.

The optional "component" parameter defines the iCalendar component type
contained within the iCalendar object.

The following is an example of this header field with a value that
indicates an event message.


        Content-Type:text/calendar; method=request; charset=UTF-8;
              component=vevent

The "text/calendar" content type allows for the scheduling message type
to be included in a MIME message with other content information (i.e.,
"multipart/mixed") or included in a MIME message with a clear-text,
human-readable form of the scheduling message (i.e.,
"multipart/alternative").

In order to permit the information in the scheduling message to be
understood by MIME user agents (UA) that do not support the
"text/calendar" content type, scheduling messages SHOULD be sent with an
alternative, human-readable form of the information.


2.5 Content-Transfer-Encoding

Note that the default character set for iCalendar objects is UTF-8. A
transfer encoding SHOULD be used for iCalendar objects containing any
characters that are not part of the US-ASCII character set.


2.6 Content-Disposition

The handling of a MIME part should be based on its [RFC-2045] "Content-
Type".  However, this is not guaranteed to work in all environments.


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Some environments handle MIME attachments based on their file type or
extension. To operate correctly in these environments, implementations
may wish to include a "Content-Disposition" property to define a file
name.



3  Security Considerations

The security threats that applications must address when implementing
iTIP are detailed in [iTIP].  Two spoofing threats are identified:
Spoofing the "Organizer", and Spoofing an "Attendee". To address these
threats, the originator of an iCalendar object must be authenticated by
a recipient.  Once authenticated, a determination can be made as to
whether or not the originator is authorized to perform the requested
operation. Compliant applications MUST support signing and encrypting
text/calendar attachments using a mechanism based on Security Multiparts
for MIME [RFC-1847] to facilitate the authentication the originator of
the iCalendar object. Implementations MAY provide a means for users to
disable signing and encrypting.  The steps are described below:

1. The iCalendar object MUST be signed by the "Organizer" sending an
update or the "Attendee" sending a reply.

2.  Using the [RFC-1847]-compliant security mechanism, determine who
signed the iCalendar object. This is the "signer". Note that the signer
is not necessarily the person sending an e-mail message since an e-mail
message can be forwarded.

3. Correlate the signer to an "ATTENDEE" property in the iCalendar
object.  If the signer cannot be correlated to an "ATTENDEE" property,
ignore the message.

4. Determine whether or not the "ATTENDEE" is authorized to perform the
operation as defined by [iTIP]. If the conditions are not met, ignore
the message.

5. If all the above conditions are met, the message can be processed.

To address the confidentiality security threats, signed iMIP messages
SHOULD be encrypted by a mechanism based on Security Multiparts for MIME
[RFC-1847].

It is possible to receive iMIP messages sent by someone working on
behalf of another "Calendar User". This is determined by examining the
"sent-by" parameter in the relevant "ORGANIZER" or "ATTENDEE" property.
[iCAL] and [iTIP] provide no mechanism to verify that a "Calendar User"
has authorized someone else to work on their behalf.  To address this
security issue, implementations MUST provide mechanisms for the
"Calendar Users" to make that decision before applying changes from
someone working on behalf of a "Calendar User".





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4  Examples


4.1 Single Component With An ATTACH Property

This minimal message shows how an iCalendar object references an
attachment. The attachment is accessible via its URL.


From: sman@netscape.com
To: stevesil@microsoft.com
Subject: Phone Conference
Mime-Version: 1.0
Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit

BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ORGANIZER:mailto:sman@netscape.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:sman@netscape.com
ATTENDEE;RSVP=YES:mailto:stevesil@microsoft.com
DTSTAMP:19970611T190000Z
DTSTART:19970701T210000Z
DTEND:19970701T230000Z
SUMMARY:Phone Conference
DESCRIPTION:Please review the attached document.
UID:calsvr.example.com-873970198738777
ATTACH:ftp://ftp.bar.com/pub/docs/foo.doc
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR


4.2 Using Multipart Alternative for Low Fidelity Clients

This example shows how a client can emit a multipart message that
includes both a plain text version as well as the full iCalendar object.
Clients that do not support text/calendar will still be capable of
rendering the plain text representation.

From: foo1@example.com
To: foo2@example.com
Subject: Phone Conference
Mime-Version: 1.0
Content-Type: multipart/alternative;boundary="01BD3665.3AF0D360"

--01BD3665.3AF0D360
Content-Type: text/plain;charset=us-ascii
Content-Transfer-Encoding: 7bit

This is an alternative representation of a TEXT/CALENDAR MIME Object


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When: 7/1/1997 10:00AM PDT - 7/1/97 10:30AM PDT
Where:
Organizer: foo1@example.com
Summary: Phone Conference

--01BD3665.3AF0D360
Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit

BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES;TYPE=INDIVIDUAL:mailto:foo2@example.com
DTSTAMP:19970611T190000Z
DTSTART:19970701T170000Z
DTEND:19970701T173000Z
SUMMARY:Phone Conference
UID:calsvr.example.com-8739701987387771
SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR

--01BD3665.3AF0D360


4.3 Single Component With An ATTACH Property and Inline Attachment

This example shows how a message containing an iCalendar object
references an attached document. The reference is made using a Content-
id (CID). Thus, the iCalendar object and the document are packaged in a
multipart/related encapsulation.


From: foo1@example.com
To: foo2@example.com
Subject: Phone Conference
Mime-Version: 1.0
Content-Type: multipart/related; boundary="boundary-example-1";
              type=text/calendar

--boundary-example-1

Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event.vcs"

BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST


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VERSION:2.0
BEGIN:VEVENT
ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES;TYPE=INDIVIDUAL:mailto:foo2@example.com
DTSTAMP:19970611T190000Z
DTSTART:19970701T180000Z
DTEND:19970701T183000Z
SUMMARY:Phone Conference
UID:calsvr.example.com-8739701987387771
ATTACH:cid:123456789@example.com
SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR

--boundary-example-1
Content-Type: application/msword; name="FieldReport.doc"
Content-Transfer-Encoding: base64
Content-Disposition: inline; filename="FieldReport.doc"
Content-ID: <123456789@example.com>

0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAABAAAARAAAAAAA
AAAAEAAAQAAAAAEAAAD+////AAAAAEUAAAD/////////////////////////////////
...

--boundary-example-1--

4.4 Multiple Similar Components

Multiple iCalendar components of the same type can be included in the
iCalendar object when the METHOD is the same for each component.


From: foo1@example.com
To: foo2@example.com
Subject: Summer Company Holidays
Mime-Version: 1.0
Content-Type:text/calendar; method=PUBLISH; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event.vcs"

BEGIN:VCALENDAR
PRODID:-//ACME/DESKTOPCALENDAR//EN
METHOD:PUBLISH
VERSION:2.0
BEGIN:VEVENT
ORGANIZER:MAILTO:FOO1@EXAMPLE.COM
DTSTAMP:19970611T150000Z
DTSTART:19970701T150000Z
DTEND:19970701T230000Z
SUMMARY:Company Picnic
DESCRIPTION:Food and drink will be provided
UID:CALSVR.EXAMPLE.COM-873970198738777-1


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SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
BEGIN:VEVENT
ORGANIZER:MAILTO:FOO1@EXAMPLE.COM
DTSTAMP:19970611T190000Z
DTSTART:19970715T150000Z
DTEND:19970715T230000Z
SUMMARY:Company Bowling Tournament
DESCRIPTION:We have 10 lanes reserved
UID:CALSVR.EXAMPLE.COM-873970198738777-2
SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR


4.5 Multiple Mixed Components

Different component types must be encapsulated in separate iCalendar
objects.


From: foo1@example.com
To: foo2@example.com
Subject: Phone Conference
Mime-Version: 1.0
Content-Type:multipart/mixed;boundary="--FEE3790DC7E35189CA67CE2C"

This is a multi-part message in MIME format.

----FEE3790DC7E35189CA67CE2C
Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event1.vcs"

BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VEVENT
ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES;TYPE=INDIVIDUAL:mailto:foo2@example.com
DTSTAMP:19970611T190000Z
DTSTART:19970701T210000Z
DTEND:19970701T230000Z
SUMMARY:Phone Conference
DESCRIPTION:Discuss what happened at the last meeting
UID:calsvr.example.com-8739701987387772
SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR


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----FEE3790DC7E35189CA67CE2C
Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding:7bit
Content-Disposition: attachment; filename="todo1.vcs"

BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST
VERSION:2.0
BEGIN:VTODO
DUE:19970701T090000-0700
ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES:mailto:foo2@example.com
SUMMARY:Phone Conference
DESCRIPTION:Discuss a new location for the company picnic
UID:calsvr.example.com-td-8739701987387773
SEQUENCE:0
STATUS:NEEDS ACTION
END:VEVENT
END:VCALENDAR

----FEE3790DC7E35189CA67CE2C

4.6 Detailed Components With An ATTACH Property

This example shows the format of a message containing a group meeting
between three individuals. The multipart/related encapsulation is used
because the iCalendar object contains an ATTACH property that uses a CID
to reference the attachment.

From: foo1@example.com
MIME-Version: 1.0
To: foo2@example.com,foo3@example.com
Subject: REQUEST - Phone Conference
Content-Type:multipart/related;boundary="--FEE3790DC7E35189CA67CE2C"

----FEE3790DC7E35189CA67CE2C
Content-Type: multipart/alternative;
              boundary="--00FEE3790DC7E35189CA67CE2C00"

----00FEE3790DC7E35189CA67CE2C00
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

When: 7/1/1997 10:00PM PDT- 7/1/97 10:30 PM PDT
Where:
Organizer: foo1@example.com
Summary: Let's discuss the attached document

----00FEE3790DC7E35189CA67CE2C00

Content-Type:text/calendar; method=REQUEST; charset=US-ASCII;


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                 Component=vevent
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event.vcs"

BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN
PROFILE:REQUEST
PROFILE-VERSION:1.0
VERSION:2.0
BEGIN:VEVENT
ORGANIZER:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:foo1@example.com
ATTENDEE;RSVP=YES;TYPE=INDIVIDUAL:mailto:foo2@example.com
ATTENDEE;RSVP=YES;TYPE=INDIVIDUAL:mailto:foo3@example.com
DTSTAMP:19970611T190000Z
DTSTART:19970621T170000Z
DTEND:199706211T173000Z
SUMMARY:Let's discuss the attached document
UID:calsvr.example.com-873970198738777-8aa
ATTACH:cid:calsvr.example.com-12345aaa
SEQUENCE:0
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR

----00FEE3790DC7E35189CA67CE2C00

----FEE3790DC7E35189CA67CE2C
Content-Type: application/msword; name="FieldReport.doc"
Content-Transfer-Encoding: base64
Content-Disposition: inline; filename="FieldReport.doc"
Content-ID: <calsvr.example.com-12345aaa>


R0lGODdhTAQZAJEAAFVVVd3d3e4AAP///ywAAAAATAQZAAAC/5yPOSLhD6OctNqLs94XqAG
4kiW5omm6sq27gvH8kzX9o1y+s73/g8MCofEovGITCoxKMbyCR16cNSq9YrNarfcrvdriIH
5LL5jE6rxc3G+v2cguf0uv2Oz+v38L7/DxgoOKjURnjIIbe3yNjo+AgZWYVIWWl5iZnJY6J.
..

----FEE3790DC7E35189CA67CE2C


5  Recommended Practices

This section outlines a series of recommended practices when using a
messaging transport to exchange iCalendar objects.


5.1 Use of Content and Message IDs

The [iCAL] specification makes frequent use of the URI for data types in
properties such as "DESCRIPTION", "ATTACH", "CONTACT" and others. Two
forms of URIs are Message ID (MID) and Content ID (CID). These are
defined in [RFC-2111]. Although [RFC-2111] allows referencing messages


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or MIME body parts in other MIME entities or stores, it is strongly
recommended that iMIP implementations include all referenced messages
and body parts in a single MIME entity. Simply put, if an iCalendar
object contains CID or MID references to other messages or body parts,
implementations should ensure that these messages and/or body parts are
transmitted with the iCalendar object. If they are not there is no
guarantee that the receiving "CU" will have the access or the
authorization to view those objects.

6  Bibliography

[CHST] Character Sets, ftp://ftp.isi.edu/in-
notes/iana/assignments/character-sets

[iCAL] "Internet Calendaring and Scheduling Core Object Specification -
iCalendar", Internet-Draft, July 1997, ftp://ftp.ietf.org/internet-
drafts/draft-ietf-calsch-ical-07.txt.

[ICMS] "Internet Calendaring Model Specification", Internet-Draft, July
1997, ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-mod-03.txt.

[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-04.txt.

 [RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", STD 11, RFC-822, August 1982.

[RFC-1847]. J. Galvin, S. Murphy, S. Crocker & N. Freed, "Security
Multiparts for MIME: Multipart/Signed and Multipart/Encrypted", RFC-
1847, October 1995.

 [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.

[RFC-2111] E. Levinson, "Content-ID and Message-ID Uniform Resource
Locators", RFC-2111, March 1997.







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                           September 15, 1998

7  Authors Addresses

The following address information is provided in a vCard v3.0,
Electronic Business Card, format.


BEGIN:VCARD
VERSION:3.0
N:Dawson;Frank
FN:Frank Dawson
ORG:Lotus Development Corporation
ADR;WORK;POSTAL;PARCEL:;;6544 Battleford
 Drive;Raleigh;NC;27613-3502;USA
TEL;WORK;MSG:+1-919-676-9515
TEL;WORK;FAX:+1-919-676-9564
EMAIL;INTERNET:fdawson@earthlink.net
URL:http://home.earthlink.net/~fdawson
END:VCARD

BEGIN:VCARD
VERSION:3.0
N:Mansour;Steve
FN:Steve Mansour
ORG:Netscape Communications Corporation
ADR;WORK;POSTAL;PARCEL:;;501 East Middlefield Road;Mountain
 View;CA;94043;USA
TEL;WORK;MSG:+1-650-937-2378
TEL;WORK;FAX:+1-650-937-2103
EMAIL;INTERNET:sman@netscape.com
END:VCARD

BEGIN:VCARD
VERSION:3.0
N:Silverberg;Steve
FN:Steve Silverberg
ORG:Microsoft Corporation
ADR;WORK;POSTAL;PARCEL:;;One Microsoft Way;
 Redmond;WA;98052-6399;USA
TEL;WORK;MSG:+1-425-936-9277
TEL;WORK;FAX:+1-425-936-8019
EMAIL;INTERNET:stevesil@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 chairmen of
that working group are:


BEGIN:VCARD
VERSION:3.0
N:Ganguly;Anik
FN:Anik Ganguly
ORG:OnTime, Inc.


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Internet DraftiCalendar Message-based Interoperability Protocol (iMIP)
                           September 15, 1998

ADR;WORK;POSTAL;PARCEL:10 Floor;;21700 Northwestern
 Highway;Southfield;MI;48075;USA
TEL;WORK;MSG:+1-810-559-5955
TEL;WORK;FAX:+1-810-559-5034
EMAIL;INTERNET:anik@ontime.com
END:VCARD

BEGIN:VCARD
VERSION:3.0
N:Moskowitz;Robert
FN:Robert Moskowitz
EMAIL;INTERNET:rgm-ietf@htt-consult.com
END:VCARD

8  Full Copyright Statement

"Copyright (C) The Internet Society (1998).  All Rights Reserved.

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 implementation 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.
















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