Mailcap_Files

   When reading MIME messages, Pine uses a mailcap file to determine
   how to display message parts. Mailcap files are described in RFC
   1524, a copy of which can be found as PMDF_ROOT:[DOC.RFC]RFC1524.
   Or see the PMDF User's Guide which gives a brief overview of
   mailcap files.

   The default mailcap filename is MAILCAP. in the PMDF_INIT
   directory, unless the logical name PMDF_MAILCAP_DIR is defined,
   in which case the list of directories defined by PMDF_MAILCAP_DIR
   is searched for the file MAILCAP., in the order listed. The first
   entry found in the list of files will be used. For instance, with
   the following PMDF_MAILCAP_DIR definition, PMDF will use a user's
   own mailcap file, if they have one, and if the user does not have
   a personal mailcap file, PMDF will use a mailcap file in the PMDF
   table directory:

   $ DEFINE/SYSTEM PMDF_MAILCAP_DIR PMDF_INIT:,PMDF_TABLE:

   Note that a trailing colon is necessary if logical names are used
   because the filename MAILCAP. is appended to whatever value you
   have specified.