MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML)
RFC 2110

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Network Working Group                                          J. Palme
Request for Comments: 2110                     Stockholm University/KTH
Category: Standards Track                                    A. Hopmann
                                                  Microsoft Corporation
                                                             March 1997

 MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML)

Status of this Document

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   Although HTML [RFC 1866] was designed within the context of MIME,
   more than the specification of HTML as defined in RFC 1866 is needed
   for two electronic mail user agents to be able to interoperate using
   HTML as a document format. These issues include the naming of objects
   that are normally referred to by URIs, and the means of aggregating
   objects that go together. This document describes a set of guidelines
   that will allow conforming mail user agents to be able to send,
   deliver and display these objects, such as HTML objects, that can
   contain links represented by URIs. In order to be able to handle
   inter-linked objects, the document uses the MIME type
   multipart/related and specifies the MIME content-headers "Content-
   Location" and "Content-Base".

Table of Contents

   1. Introduction..............................................  2
   2. Terminology...............................................  3
      2.1 Conformance requirement terminology...................  3
      2.2 Other terminology.....................................  4
   3. Overview..................................................  5
   4. The Content-Location and Content-Base MIME Content Headers  6
      4.1 MIME content headers..................................  6
      4.2 The Content-Base header...............................  7
      4.3 The Content-Location Header...........................  7
      4.4 Encoding of URIs in e-mail headers....................  8
   5. Base URIs for resolution of relative URIs.................  8
   6. Sending documents without linked objects..................  9
   7. Use of the Content-Type: Multipart/related................  9
   8. Format of Links to Other Body Parts....................... 11

Palme & Hopmann             Standards Track                     [Page 1]
RFC 2110                         MHTML                        March 1997

      8.1 General principle..................................... 11
      8.2 Use of the Content-Location header.................... 11
      8.3 Use of the Content-ID header and CID URLs............. 12
   9 Examples................................................... 12
      9.1 Example of a HTML body without included linked objects 12
      9.2 Example with absolute URIs to an embedded GIF picture  13
      9.3 Example with relative URIs to an embedded GIF picture  13
      9.4 Example using CID URL and Content-ID header to an
          embedded GIF picture.................................. 14
   10. Content-Disposition header............................... 15
   11. Character encoding issues and end-of-line issues......... 15
   12. Security Considerations.................................. 16
   13. Acknowledgments.......................................... 17
   14. References............................................... 18
   15. Author's Address......................................... 19

Mailing List Information

   Further discussion on this document should be done through the
   mailing list MHTML@SEGATE.SUNET.SE.

   To subscribe to this list, send a message to
      LISTSERV@SEGATE.SUNET.SE
   which contains the text
   SUB MHTML <your name (not your e-mail address)>

   Archives of this list are available by anonymous ftp from
      FTP://SEGATE.SUNET.SE/lists/mHTML/
   The archives are also available by e-mail. Send a message to
   LISTSERV@SEGATE.SUNET.SE with the text "INDEX MHTML" to get a list
   of the archive files, and then a new message "GET <file name>" to
   retrieve the archive files.

   Comments on less important details may also be sent to the editor,
   Jacob Palme <jpalme@dsv.su.se>.

   More information may also be available at URL:
   HTTP://www.dsv.su.se/~jpalme/ietf/jp-ietf-home.HTML

1. Introduction

   There are a number of document formats, HTML [HTML2], PDF [PDF] and
   VRML for example, which provide links using URIs for their
   resolution. There is an obvious need to be able to send documents in
   these formats in e-mail [RFC821=SMTP, RFC822]. This document gives
   additional specifications on how to send such documents in MIME [RFC
   1521=MIME1] e-mail messages. This version of this standard was based