RFC 1524 (rfc1524) - Page 3 of 12
A User Agent Configuration Mechanism For Multimedia Mail Format Information
Alternative Format: Original Text Document
RFC 1524 Multimedia Mail Configuration September 1993
Thus the overall format of a mailcap file is given, in the modified
BNF of RFC 822, as:
Mailcap-File = *Mailcap-Line
Mailcap-Line = Comment / Mailcap-Entry
Comment = NEWLINE / "#" *CHAR NEWLINE
NEWLINE =
Note that the above specification implies that comments must appear
on lines all to themselves, with a "#" character as the first
character on each comment line.
Format of a Mailcap Entry
Each mailcap entry consists of a number of fields, separated by
semi-colons. The first two fields are required, and must occur in
the specified order. The remaining fields are optional, and may
appear in any order.
The first field is the content-type, which indicates the type of data
this mailcap entry describes how to handle. It is to be matched
against the type/subtype specification in the "Content-Type" header
field of an Internet mail message. If the subtype is specified as
"*", it is intended to match all subtypes of the named content-type.
The second field, view-command, is a specification of how the message
or body part can be viewed at the local site. Although the syntax of
this field is fully specified, the semantics of program execution are
necessarily somewhat operating system dependent. UNIX semantics are
given in Appendix A.
The optional fields, which may be given in any order, are as follows:
-- The "compose" field may be used to specify a program that can be
used to compose a new body or body part in the given format. Its
intended use is to support mail composing agents that support the
composition of multiple types of mail using external composing
agents. As with the view-command, the semantics of program
execution are operating system dependent, with UNIX semantics
specified in Appendix A. The result of the composing program may
be data that is not yet suitable for mail transport -- that is, a
Content-Transfer-Encoding may need to be applied to the data.
-- The "composetyped" field is similar to the "compose" field, but is
to be used when the composing program needs to specify the
Borenstein