The text/enriched MIME Content-type
RFC 1563

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Network Working Group                                      N. Borenstein
Request for Comments: 1563                                      Bellcore
Obsoletes: 1523                                             January 1994
Category: Informational

                  The text/enriched MIME Content-type

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Abstract

   MIME [RFC-1341, RFC-1521] defines a format and general framework for
   the representation of a wide variety of data types in Internet mail.
   This document defines one particular type of MIME data, the
   text/enriched type, a refinement of the "text/richtext" type defined
   in RFC 1341.  The text/enriched MIME type is intended to facilitate
   the wider interoperation of simple enriched text across a wide
   variety of hardware and software platforms.

Table of Contents

   The Text/enriched MIME type..............................  2
   Formatting Commands......................................  4
         Font-Alteration Commands...........................  4
         Fill/Justification Commands........................  5
         Indentation Commands...............................  6
         Miscellaneous Commands.............................  6
         Balancing and Nesting of Formatting Commands.......  7
         Unrecognized formatting commands...................  8
   White Space in Text/enriched Data........................  8
   Initial State of a text/enriched interpreter.............  8
   Non-ASCII character sets.................................  8
   Minimal text/enriched conformance........................  9
   Notes for Implementors...................................  9
   Extensions to text/enriched.............................. 10
   An Example............................................... 11
   Security Considerations.................................. 12
   Author's Address......................................... 12
   Acknowledgements......................................... 12
   References............................................... 12
   Appendix A -- A Simple enriched-to-plain Translator in C. 13
   Appendix B -- Differences from RFC 1341 text/richtext.... 15

Borenstein                                                      [Page 1]
RFC 1563             A text/enriched type for MIME          January 1994

The Text/enriched MIME type

   In order to promote the wider interoperability of simple formatted
   text, this document defines an extremely simple subtype of the MIME
   content-type "text", the "text/enriched" subtype.  This subtype was
   designed to meet the following criteria:

      1.  The syntax must be extremely simple to parse,
          so that even teletype-oriented mail systems can
          easily strip away the formatting information and
          leave only the readable text.

      2.  The syntax must be extensible to allow for new
          formatting commands that are deemed essential for
          some application.

      3.  If the character set in use is ASCII or an 8-
          bit ASCII superset, then the raw form of the data
          must be readable enough to be largely
          unobjectionable in the event that it is displayed
          on the screen of the user of a non-MIME-conformant
          mail reader.

      4.  The capabilities must be extremely limited, to
          ensure that it can represent no more than is
          likely to be representable by the user's primary
          word processor.  While this limits what can be
          sent, it increases the likelihood that what is
          sent can be properly displayed.

   This document defines a new MIME content-type, "text/enriched".  The
   content-type line for this type may have one optional parameter, the
   "charset" parameter, with the same values permitted for the
   "text/plain" MIME content-type.

   The syntax of "text/enriched" is very simple.  It represents text in
   a single character set -- US-ASCII by default, although a different
   character set can be specified by the use of the "charset" parameter.
   (The semantics of text/enriched in non-ASCII character sets are
   discussed later in this document.)  All characters represent
   themselves, with the exception of the "<" character (ASCII 60), which
   is used to mark the beginning of a formatting command.  Formatting
   instructions consist of formatting commands surrounded by angle
   brackets ("<>", ASCII 60 and 62).  Each formatting command may be no
   more than 60 characters in length, all in US-ASCII, restricted to the
   alphanumeric and hyphen ("-") characters.  Formatting commands may be
   preceded by a solidus ("/", ASCII 47), making them negations, and
   such negations must always exist to balance the initial opening

Borenstein                                                      [Page 2]