RFC 1049 (rfc1049) - Page 1 of 8

Content-type header field for Internet messages

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Network Working Group                                           M. Sirbu
Request for Comments:  1049                                          CMU
                                                              March 1988

           A CONTENT-TYPE HEADER FIELD FOR INTERNET MESSAGES

STATUS OF THIS MEMO

   This RFC suggests proposed additions to the Internet Mail Protocol,
   RFC-822, for the Internet community, and requests discussion and
   suggestions for improvements.  Distribution of this memo is
   unlimited.

ABSTRACT

   A standardized Content-type field allows mail reading systems to
   automatically identify the type of a structured message body and to
   process it for display accordingly.  The structured message body must
   still conform to the RFC-822 requirements concerning allowable
   characters.  A mail reading system need not take any specific action
   upon receiving a message with a valid Content-Type header field.  The
   ability to recognize this field and invoke the appropriate display
   process accordingly will, however, improve the readability of
   messages, and allow the exchange of messages containing mathematical
   symbols, or foreign language characters.

                             Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 1
   2. Problems with Structured Messages . . . . . . . . . . . . . . . 3
   3. The Content-type Header Field . . . . . . . . . . . . . . . . . 5
        3.1. Type Values  . . . . . . . . . . . . . . . . . . . . . . 5
        3.2. Version Number . . . . . . . . . . . . . . . . . . . . . 6
        3.3. Resource Reference . . . . . . . . . . . . . . . . . . . 6
        3.4. Comment. . . . . . . . . . . . . . . . . . . . . . . . . 7
   4. Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1. Introduction

   As defined in RFC-822, [2], an electronic mail message consists of a
   number of defined header fields, some containing structured
   information (e.g., date, addresses), and a message body consisting of
   an unstructured string of ASCII characters.

   The success of the Internet mail system has led to a desire to use
   the mail system for sending around information with a greater degree
   of structure, while remaining within the constraints imposed by the
   limited character set.  A prime example is the use of mail to send a



Sirbu
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