[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 RFC 3458

Network Working Group                                           E. Burger
Internet Draft                                         SnowShore Networks
Document: draft-ietf-vpim-hint-01.txt                          E. Candell
Category: Standards Track                        Comverse Network Systems
Expires May 2001                                                 C. Eliot
                                                    Microsoft Corporation
                                                                 G. Klyne
                                                     Content Technologies
                                                        November 24, 2000


                   Message Context for Internet Mail

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026 [1].

   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 and may be updated, replaced, or obsoleted by other documents
   at any time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt .

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html .

   This document is a work product of the IETF Voice Profile for
   Internet Mail (vpim) Work Group.  The URL for the VPIM website is
   <http://www.vpim.org>.


   1. Abstract

   This memo describes a new RFC822 message header, "Message-Context".
   This header provides information about the context and presentation
   characteristics of a message.

   A receiving user agent (UA) may use this information as a hint to
   optimally present the message.







                           Expires 5/13/01                    [Page 1]

                  Message Context for Internet Mail      November 2000

Table of Contents

1. ABSTRACT...........................................................1
2. INTRODUCTION.......................................................3
3. CONVENTIONS USED IN THIS DOCUMENT..................................3
4. MOTIVATION.........................................................4
5. FUNCTIONAL REQUIREMENTS............................................5
6. DETERMINING THE MESSAGE CONTEXT....................................6
7. MESSAGE-CONTEXT REFERENCE FIELD....................................6
7.1. Message-Context Syntax...........................................7
7.2. message-context-class Syntax.....................................7
7.2.1. voice-message..................................................7
7.2.2. fax-message....................................................7
7.2.3. video-message..................................................7
7.2.4. short-message..................................................7
7.2.5. mail-message...................................................8
7.2.6. none...........................................................8
8. SECURITY CONSIDERATIONS............................................8
9. IANA CONSIDERATIONS................................................8
9.1. Message-Context Registration.....................................8
9.2. Primary Context Class Registrations..............................9
9.2.1. Registration Template..........................................9
9.2.2. voice-message.................................................10
9.2.3. fax-message...................................................11
9.2.4. video-message.................................................11
9.2.5. short-message.................................................12
9.2.6. video-message.................................................13
9.2.7. mail-message..................................................13
9.2.8. video-message.................................................14
9.2.9. none..........................................................14
10. APPENDIX: SOME MESSAGING SCENARIOS...............................15
10.1. Internet e-mail................................................15
10.2. Short text messaging service...................................16
10.3. Facsimile......................................................16
10.4. Voice mail.....................................................17
10.5. Multimedia message.............................................17
11. REFERENCES.......................................................18
12. ACKNOWLEDGMENTS..................................................18
13. AUTHOR'S ADDRESSES...............................................19
14. FULL COPYRIGHT STATEMENT.........................................20








Burger et. al.             Expires 5/24/01                    [Page 2]

                  Message Context for Internet Mail      November 2000

   2. Introduction

   This document describes a mechanism to allow senders of a multi-part
   Internet mail message to convey presentational information of the
   message as a whole.  This information specifies the context of the
   message.  With this information, the user agent (UA) can optimally
   present the message to the user in the context she expects.

   In this document, the "message context" is the context the user
   expects to interact with the message.  For example, a message may be
   e-mail, voice mail, fax mail, etc.  A smart UA may have specialized
   behavior based on the context of the message.

   This document specifies a RFC 822 header called "Message-Context".
   The mechanism is in some ways similar to the use of the Content-
   Disposition MIME entity described in [2].  Content-Disposition gives
   clues to the receiving User Agent (UA) for how to display a given
   body part.  Message-Context gives clues to the receiving UA for the
   context of the message display as a whole.  This allows the
   receiving UA to present the message in a meaningful and helpful way
   to the recipient.

   Typical uses for this mechanism include:
   o    Selecting a special viewer for a given message.
   o    Selecting an icon indicating the kind of message in a displayed
        list of messages.
   o    Arraigning messages in an inbox display.
   o    Filtering messages the UA presents when the user has limited
        access.


   3. Conventions used in this document

   This document refers generically to the sender of a message in the
   masculine (he/him/his) and the recipient of the message in the
   feminine (she/her/hers).  This convention is purely for convenience
   and makes no assumption about the gender of a message sender or
   recipient.

   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 [3].

   FORMATTING NOTE: Notes, such at this one, provide additional
   nonessential information that the reader may skip without missing
   anything essential.  The primary purpose of these non-essential
   notes is to convey information about the rationale of this document,
   or to place this document in the proper historical or evolutionary
   context.  Readers whose sole purpose is to construct a conformant
   implementation may skip such information.  However, it may be of use
   to those who wish to understand why we made certain design choices.


Burger et. al.             Expires 5/24/01                    [Page 3]

                  Message Context for Internet Mail      November 2000


   4. Motivation

   Multimedia messaging systems receive messages that a UA may present
   in variety of ways.  For example, traditional e-mail uses simple
   text messages that the recipient displays and edits.  One UA may
   automatically print Fax images.  Another UA may play voice messages
   through a telephone handset.  Likewise, a receiving desktop computer
   may process or present documents transferred over e-mail using a
   local application.  Emerging and future developments may deliver
   other forms of information that have their own characteristics for
   user presentation, such as video messages and short text messages.

   An often-requested characteristic for multimedia messaging systems
   is to collect received messages in a "universal inbox", and to offer
   them to the user as a combined list.

   In the context of "unified messaging", different message contexts
   may have different implied semantics.  For example, some users may
   perceive voicemail to have an implicit assumption of urgency.  Thus
   they may wish to gather them together and process them before other
   messages.  This results in the end-user receiving agent needing to
   be able to identify voicemail and distinguish it from other
   messages.

   The uses of this kind of presentation characteristic for each
   message is multi-fold:

   o    Display an indication to the user (e.g., by a suitably
        evocative icon along with other summary fields),

   o    Auto-forward a given message type into another messaging
        environment (e.g., short text to a mobile short message
        service),

   o    Prioritize and group messages in an inbox display list,

   o    Suggest appropriate default handling for presentation,

   o    Suggest appropriate default handling for reply, forward, etc.,
        and

   o    Filter the message list for presentation via limited-capability
        user interfaces (e.g., there is no point in offering images
        when the user is connected by a voice-only telephone user
        interface).

   A problem faced by multimedia messaging systems is that it is not
   always easy to decide the context of a received message.  For
   example, consider the following scenarios.



Burger et. al.             Expires 5/24/01                    [Page 4]

                  Message Context for Internet Mail      November 2000

   o    A message that contains audio and image data:  Is this a fax
        message that happens to have some voice commentary?  Is it a
        voice message that is accompanied by some supplementary
        diagrams?  Is it a fully multimedia message, in which all parts
        are expected to carry equal significance?

   o    A message containing text and audio data:  Is this e-mail with
        an MP3 music attachment?  Is it a voice message that happens to
        have been generated with an initial text header for the benefit
        of non-voice-enabled e-mail receivers?

   The message context does relate to the message media content.
   However, it is not the same thing.  As shown above, the media type
   used in a message is not sufficient to indicate the message context.
   One cannot determine a priori which media types to use in
   alternative (gateway) message.  Also, what if the user cares about
   distinguishing traditional e-mail text from SMS messages?  They are
   both the same media type, text, but they have different user
   contexts.


   5. Functional Requirements

   The goals stated above lead to the following functional
   requirements.

   For receivers:
   o    Identify a message as belonging to a message class.

   o    Incorrect or invalid message classification must not result in
        failure to transfer or inability to present a message.


   For senders:
   o    Specify message classes by the originating user's choice of
        authoring tool or simple user interaction.


   For both:
   o    Specify a well-defined set of message classes to make
        interoperability between mail user agents (UAs) possible.

   o    Message classification information has to be interpretable in
        reasonable fashion by many different user agent systems.

   o    The mechanism should be extensible to allow for the
        introduction of new kinds of messages.






Burger et. al.             Expires 5/24/01                    [Page 5]

                  Message Context for Internet Mail      November 2000

   6. Determining the Message Context

   One method of indicating the interpretation context of a message is
   to examine the media types in the message.  However, this requires
   the UA to scan the entire message before it can make this
   determination.  This approach is particularly burdensome for the
   multi-media mail situation, as voice and especially video mail
   objects are quite large.

   We considered indicating the message context by registering a
   multipart/* MIME subtype (Content-Type).  For example, the VPIM Work
   Group has registered multipart/voice-message to indicate that a
   message is primarily voice mail [4].  However, multipart/voice-
   message is identical in syntax to multipart/mixed.  The only
   difference is that VPIM mail transfer agents and user agents
   recognize that they can perform special handling of the message
   based on it being a voice mail message.  Moreover, Content-Type
   refers to a given MIME body part, not to the message as a whole.

   We wish to avoid scanning the entire message.  In addition, we wish
   to avoid having to create multiple aliases for multipart/mixed every
   time someone identifies a new primary content type.  Multiple
   aliases for multipart/mixed are not desirable as they remove the
   possibility for specifying a message as multipart/alternate,
   multipart/parallel, or multipart/encrypted, for example.

   Since the message context is an attribute of the entire message, it
   is logical to define a new top-level (RFC 822 [5]) message
   attribute.  To this end, this document introduces the message
   attribute "Message-Context".

   The values for Message-Context MUST be either IANA registered values
   or experimental, X- tokens.  This ensures that user agents from
   different vendors will interoperate and perform in a uniform manner
   without an undue burden on the vendors.

   Message-Context only serves to identify the message context.  It
   does not provide any indication of content that the UA must be
   capable of delivering.  It does not imply any message disposition or
   delivery notification.  There is a related effort to define Critical
   Content of Internet Mail [6] that one might use to perform these
   tasks.

   Message-Context is only an indicator.  One can conceive of goofy
   situations, such as a message marked "voice-message" but without an
   audio body part.  In this case, the fact that the contents of a
   message don't match its context MUST NOT generate an error report or
   fail to deliver or process the message.


   7. Message-Context Reference Field


Burger et. al.             Expires 5/24/01                    [Page 6]

                  Message Context for Internet Mail      November 2000

   The Message-Context reference field is a top-level header inserted
   by the sending UA to indicate the context of the message.

  7.1. Message-Context Syntax

   The syntax of the Message-Context field, formatted according to the
   ABNF [7] is as follows.  Note that "Message-Context" is case
   insensitive, per RFC 822.

        "Message-Context" ":" message-context-class CRLF

  7.2. message-context-class Syntax

   The message-context-class indicates the context of the message.
   This is an IANA registered value.  Current values for message-
   context-class are as follows.

        message-context-class =  1 *( [ "voice-message"]
                                      [ "fax-message" ]
                                      [ "video-message" ]
                                      [ "short-message" ]
                                      [ "mail-message" ]
                                      [ "none" ]
                                      extension-type )

        extension-type = token   ; Defined and registered per Section 8
                       / x-token ; Experimental, private use

        token = <syntax as defined by [8],
                 but not starting with the characters "X-" or "x-">

        x-token = <syntax as defined by [8] for private use>

     7.2.1. voice-message

   The voice-message class states the message is a voice message.

     7.2.2. fax-message

   The fax-message class states the message is a facsimile message.

     7.2.3. video-message

   The video-message class states the message is a video message.

     7.2.4. short-message

   The short-message class states the message is a short text message,
   such as a short text message service (SMS) message or text pager
   message.



Burger et. al.             Expires 5/24/01                    [Page 7]

                  Message Context for Internet Mail      November 2000

     7.2.5. mail-message

   The mail-message class states the message is a normal internet mail
   message, with or without attachments.

     7.2.6. none

   The none class states there is no context information for this
   message.  This class is functionally identical to the mail-message
   class.

   If a message has no Message-Context reference field, "none" MUST be
   the default value.


   8. Security Considerations

   The intention for this header is to indicate message context only.
   One can imagine someone creating an "Application" Message-Context.
   A poorly designed user agent could blindly execute a mailed program
   based on the Message-Context.  Don't do that!

   One can envision a denial of service attack by bombing a receiver
   with a message that has a Message-Context that doesn't fit the
   profile of the actual body parts.  This is why the receiver MUST
   consider the Message-Context to be a hint only.  The receiver SHOULD
   NOT rely on the Message-Context exclusively for presentation
   processing.


   9. IANA Considerations

   Following the policies outlined in [9] as "Specification Required",
   IANA assigns values for Message-Context.

  9.1. Message-Context Registration

   To: ietf-types@iana.org
   Subject: Registration of New Top-Level Header Field Message-Context

   Header name:
   Message-Context

   Required parameters:
   Single 7bit text value

   Parameter value:
   The parameter value specifies the message context for the message.

   Security considerations:
   The intention for this header is to indicate media content type
   only.  One can imagine one creating an "Application" primary content

Burger et. al.             Expires 5/24/01                    [Page 8]

                  Message Context for Internet Mail      November 2000

   type, and have a poorly designed user agent blindly execute a mailed
   program.

   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   Mail
   VPIM
   FPIM

   Additional information: none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON


  9.2. Primary Context Class Registrations

     9.2.1. Registration Template

   NOTE: Is ietf-types the appropriate address?  Do we need to set up
   another address with IANA?

   NOTE: What is the appropriate discussion list to socialize new tags
   on?  Is it imc822?

   In the following template, a pipe symbol, "|", precedes instructions
   or other helpful material.  Be sure to replace "<classname>" with
   the class name you are defining.


   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class <classname>

   Message-Context class name:
   <classname>

   Summary of the message class:
       | Include a short (no longer than 4 lines) description or summary
       | Examples:
       |   "Palmtop devices have a 320x160 pixel display, so we can..."
       |   "Color fax is so different than black & white that..."

   Security considerations:
       | Describe issues related to security.  Examples include privacy
       | concerns, denial of service concerns, malicious behavior, etc.



Burger et. al.             Expires 5/24/01                    [Page 9]

                  Message Context for Internet Mail      November 2000

   Interoperability considerations:
       | Describe issues with existing RFC's or BCP's, if any.

   Published specification:
       | List the document(s) that define the context this
       | class represents
   NOTE: Since classes are pretty straight-forward, can we use the
   registration mechanism for including a full description of the class
   behavior?

   Applications that use this context class:
       | List known applications that use this context class
   NOTE: Do we need to include the Applications enumeration?

   Additional information:
       | Any other relevant information that might be useful, such
       | as related class definitions, etc.

   Person & email address to contact for further information:
       | Name & e-mail!

   Intended usage:
       | pick one of COMMON, LIMITED USE, or OBSOLETE

     9.2.2. voice-message

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class voice-message

   Message-Context class name:
   voice-message

   Security considerations:
   none

   Interoperability considerations:
   User agents declaring the primary context to be voice-message SHOULD
   conform to VPIMv2.

   Published specification:
   draft-ietf-vpim-hint-01.txt
   RFC 2421, Voice Profile for Internet Mail - version 2

   Applications that use this context class:
   VPIM

   Additional information:
   none





Burger et. al.             Expires 5/24/01                   [Page 10]

                  Message Context for Internet Mail      November 2000

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON


     9.2.3. fax-message

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class fax-message

   Message-Context class name:
   fax-message

   Security considerations:
   none

   Interoperability considerations:
   none

   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   FPIM

   Additional information:
   none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON


     9.2.4. video-message

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class video-message

   Message-Context class name:
   voice-message

   Security considerations:
   none

   Interoperability considerations:
   none



Burger et. al.             Expires 5/24/01                   [Page 11]

                  Message Context for Internet Mail      November 2000

   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   VPIM, FPIM

   Additional information:
   none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON


     9.2.5. short-message

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class short-message

   Message-Context class name:
   short-message

   Security considerations:
   none

   Interoperability considerations:
   none

   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   Mail
   VPIM
   FPIM

   Additional information:
   none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON







Burger et. al.             Expires 5/24/01                   [Page 12]

                  Message Context for Internet Mail      November 2000

     9.2.6. video-message

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class video-message

   Message-Context class name:
   voice-message

   Security considerations:
   none

   Interoperability considerations:
   none

   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   VPIM, FPIM

   Additional information:
   none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON


     9.2.7. mail-message

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class mail-message

   Message-Context class name:
   mail-message

   Security considerations:
   none

   Interoperability considerations:
   none

   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   Mail
   VPIM
   FPIM


Burger et. al.             Expires 5/24/01                   [Page 13]

                  Message Context for Internet Mail      November 2000

   Additional information:
   none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON

     9.2.8. video-message

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class video-message

   Message-Context class name:
   voice-message

   Security considerations:
   none

   Interoperability considerations:
   none

   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   VPIM, FPIM

   Additional information:
   none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON


     9.2.9. none

   To: ietf-types@iana.org
   Subject: Registration of New Message-Context class none

   Message-Context class name:
   none

   Security considerations:
   none

   Interoperability considerations:
   none

Burger et. al.             Expires 5/24/01                   [Page 14]

                  Message Context for Internet Mail      November 2000


   Published specification:
   draft-ietf-vpim-hint-01.txt

   Applications that use this context class:
   Mail
   VPIM
   FPIM

   Additional information:
   none

   Person & email address to contact for further information:
   Eric Burger
   e.burger@ieee.org

   Intended usage: COMMON


   10. APPENDIX: Some messaging scenarios

   This section is not a normative part of this document.  We include
   it here as a historical perspective on the issue of multimedia
   message types.

   These scenarios are neither comprehensive nor fixed.  For example,
   e-mails being typically text-based do not mean that they cannot
   convey a voice-message.  This very mutability serves to underline
   the desirability of providing some explicit message context hint.

  10.1. Internet e-mail

   Internet e-mail carries textual information.  Sometimes it conveys
   computer application data of arbitrary size.

   Typically, one uses e-mail for non-urgent messages, which the
   recipient will retrieve and process at a time convenient to her.

   The normal device for receiving and processing e-mail messages is
   some kind of personal computer.  Modern personal computers usually
   come with a reasonably large display and an alphanumeric keyboard.
   Audio, video, and printing capabilities are not necessarily
   available.

   One can use E-mail for communication between two parties (one-to-
   one), a small number of known parties (one-to-few) or, via an e-mail
   distribution list, between larger numbers of unknown parties (one-
   to-many).

   One of the endearing characteristics of e-mail is the way that it
   allows the recipient to forward all or part of the message a to
   another party, with or without additional comments.  It is quite

Burger et. al.             Expires 5/24/01                   [Page 15]

                  Message Context for Internet Mail      November 2000

   common for an e-mail to contain snippets of content from several
   previous messages. Similar features apply when replying to e-mail.

  10.2. Short text messaging service

   One can use a short text message to convey textual information of
   limited size.  The typical limit is 160 characters.

   The short text messaging service (SMS) is a facility that has
   evolved for use with mobile telephones, and has an associated per-
   message transmission charge.  People use SMS for relatively urgent
   messages, which the sender wishes the receiver to see and possibly
   respond to within a short time period.

   The normal device for sending and receiving a short text message is
   a mobile telephone with a small character display and a numeric-only
   keyboard.  Personal computers and personal digital assistants (PDAs)
   can also participate in short text messaging.

   Currently, the most common use of short text messages are between
   just two parties (one-to-one).

   Users often send short text messages in isolation, rather than as
   part of a longer exchange.  One use for them is as a prompt or
   invitation to communicate by some more convenient and content-rich
   method, such as a telephone call.

  10.3. Facsimile

   People use facsimile to convey image information of moderate size,
   typically a small number of pages.  Sometimes people use facsimile
   for larger documents.

   Facsimile is a facility that usually uses circuit-switched telephone
   circuits, with connection-time charges.  Message transfer takes
   place in real-time.  Thus, people often use facsimile for urgent
   communication.

   The normal device for sending and receiving a facsimile is a self-
   contained scanning and printing device connected to a telephone line
   or a desktop computer.

   Most facsimiles are between just two parties (one-to-one).  However,
   a significant portion of facsimile service is broadcast between
   multiple parties (one-to-many).

   Most facsimile exchanges are in isolation, rather than as part of a
   longer exchange.  Facsimile data is typically not suitable for
   further processing by computer.




Burger et. al.             Expires 5/24/01                   [Page 16]

                  Message Context for Internet Mail      November 2000

  10.4. Voice mail

   People use voice mail to convey audio information, almost
   exclusively human speech.

   Voice mail is a facility that usually uses circuit-switched
   telephone circuits, with modest connection-time charges, often used
   for moderately urgent messages.  A common use for them is as a
   prompt or invitation to communicate by some more convenient method,
   such as a telephone call. In most, but not all cases, the sender of
   a voice message does not want to send a message at all.  Rather,
   they wished to engage in a real-time conversation.

   The normal device for sending and receiving a voice mail is a
   telephone handset.

   Voice messages are usually sent between just two parties (one-to-
   one).

   Voice mail data is not generally suitable for further processing by
   computer.

  10.5. Multimedia message

   We define a multimedia message as a message containing more than one
   basic media type (text, image, audio, video, model, application).

   The following are some characteristics of a multimedia message.

   In some cases, a multimedia message is just e-mail with an
   attachment that a multimedia display application presents.  For
   example, I can send you an MP3 of something I recorded in my garage
   today.

   In other cases, a multimedia message represents a convergence
   between two or more of the scenarios described above.  For example,
   a voice message with an accompanying diagram or a talking head video
   message is a multimedia message.

   The characteristics will vary somewhat with the intent of the
   sender.  This in turn may affect the user agent or application used
   to render the message.











Burger et. al.             Expires 5/24/01                   [Page 17]

                  Message Context for Internet Mail      November 2000

   11. References


   1  Bradner, S., "The Internet Standards Process -- Revision 3", BCP
      9, RFC 2026, October 1996.

   2  Troost, R., Dorner, S., and Moore, K., "Communicating
      Presentation Information in Internet Messages: The Content-
      Disposition Header Field", RFC 2183, New Century Systems,
      QUALCOMM Incorporated, and University of Tennessee, August 1997.

   3  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997.

   4  Vaudreuil, G. and Parsons, G., "VPIM Voice Message MIME Sub-type
      Registration", RFC 2423, Lucent Technologies and Northern
      Telecom, September 1998.

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

   6  Burger, E. and Candell, E., "Critical Content of Internet Mail",
      draft-ietf-vpim-cc-01.txt, Work in Progress.

   7  Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax
      Specifications: ABNF", RFC 2234, Internet Mail Consortium and
      Demon Internet Ltd., November 1997.

   8  Freed, N. and Borenstein, N., "Multipurpose Internet Mail
      Extensions (MIME) Part One: Format of Internet Message Bodies",
      RFC 2045, Innosoft and First Virtual, November 1996.

   9  Alvestrand, H. and T. Narten, "Guidelines for Writing an IANA
      Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.



   12. Acknowledgments

   Many of the ideas here arose originally from a discussion with Jutta
   Degener.

   We'd also like to thank Keith Moore for helping us tighten-up our
   explanations.









Burger et. al.             Expires 5/24/01                   [Page 18]

                  Message Context for Internet Mail      November 2000

   13. Author's Addresses

   Eric Burger
   SnowShore Networks, Inc.
   c/o CRV
   1000 Winter St.
   Suite 3300
   Waltham, MA  02451-1448
   USA

   Phone: +1 781 487 5406
   Fax:   +1 781 895 9809
   Email: e.burger@ieee.org


   Emily Candell
   Comverse Network Systems
   200 Quannapowitt Pkwy.
   Wakefield, MA  01880
   USA

   Phone: +1 781 213 2324
   Email: emily@comversens.com


   Graham Klyne
   Content Technologies Ltd.
   1220 Parkview,
   Arlington Business Park
   Theale
   Reading, RG7 4SA
   United Kingdom.

   Telephone: +44 118 930 1300
   Facsimile: +44 118 930 1301
   E-mail:    GK@ACM.ORG


   Charles Eliot
   Microsoft Corporation
   One Microsoft Way
   Redmond WA 98052
   USA

   Telephone: +1 425 936 9760
   E-Mail:    charle@Microsoft.com







Burger et. al.             Expires 5/24/01                   [Page 19]

                  Message Context for Internet Mail      November 2000

   14. Full Copyright Statement

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights.  Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11.  Copies of
   claims of rights made available for publication and any assurances
   of licenses to be made available, or the result of an attempt made
   to obtain a general license or permission for the use of such
   proprietary rights by implementers or users of this specification
   can be obtained from the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to practice
   this standard.  Please address the information to the IETF Executive
   Director.

   Copyright (C) 2000 The Internet Society.  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.






Burger et. al.             Expires 5/24/01                   [Page 20]


Html markup produced by rfcmarkup 1.108, available from http://tools.ietf.org/tools/rfcmarkup/