Configuring MIME handlers

	This program uses three files to configure itself for viewing or
handling MIME attachments. MIME stands for "Multimedia Internet Mail 
Extensions", and is a standard form for providing arbitrary
information including images and audio through the normally text-based
mail system.

	The location of these files can be tailored on a per-user basis via
preferences. The default is the LIBDIR (/usr/local/lib/ml), which may
be tailored for all users on the system. If users wish to over-ride
this default location, they need to set a new directory location via
their preferences, and then copy the three files (not all of which are
necessarily in existence) to this personal directory. Then these files
may be edited to personal taste. Following are detailed descriptions
of the three files involved.

/usr/local/lib/ml/mime.types

	Defines all known MIME types. The types known to me are
built-in to the program, so this file need not be present. If it is,
it over-rides the built-in type list, and therefore must contain all
known MIME types. It is simply a list, one entry
per line, with MIME type/subtype strings and no leading or trailing
whitespace. You may wish to create this list "in reverse", since the
first entry will appear last in the program's list. 

Example:

application/postscript
application/octet-stream
image/gif
...etc.


/usr/local/lib/ml/mime.map

	Defines filename extension to MIME type/subtype mapping; for
use when loading file attachments. Several default types are built-in
to the program. If this file exists, it will over-ride the built-in
filename extension mappings, so must be complete. It contains a
filename suffix, white space, and a MIME type/subtype pair, one to a
line. Uppercase and lowercase differences are ignored.

For example:

.ps	application/postscript
.c	text/plain
.Z	application/octet-stream
.gif    image/gif


/usr/local/lib/ml/mime.handlers


	Defines MIME handlers or "helper applications" for processing 
attachments. A few types are built-in to the program and cannot be 
over-ridden. This list of built-in types may change in future releases.

	text/plain
	multipart/{anything}
	message/external-body	(we handle mail-server and FTP access
				only. Other types can be externally processed).
	message/RFC822

	The file contains type/subtype pairs, followed by a
semi-colon, and then the complete command to execute to "view" the
attachment. If %s is in the command, the message will come from a
temporary file, otherwise the message will come from stdin. Only one
%s (and no other % characters) may appear. If the program requires a
TTY for keyboard interaction, be certain to prefix the command a
command to launch an interactive terminal, such as "xterm -e".

	After the "view" command, you may optional provide a space
followed by $COMPOSE= and a command to compose a message of this
type. This command MUST put its results in a file, designated by
%s.

	You may have either a view handler or a compose handler, or
both. An entry for a specific type is terminated by an
end-of-line. There are no "continuation lines". If you use "metamail"
(from Bellcore Labs), this type of file file format should be vaguely
familiar, although there are several differences between this format
and the metamail mailcap file. It is possible to use many of the
metamail handlers, just be aware of the possible need to specify an
xterm, and the differences in $COMPOSE= syntax. A sample file is
included below, showing what I use for basic support. Any handlers not
specified results in a file-save request when viewed. Additionally, a
preference available in the Options Settings menu, allows you to be
prompted before executing any external view handler (including none),
and allows you to change it. This setting is "true" by default, so
there is no need to edit the preferences file except to turn it off,
which allows automatic processing with no interaction (where
possible).

Example:

audio/basic; play %s $COMPOSE=xterm -e audiocompose %s
image/gif; xv %s $COMPOSE=xgrabsc -s 2 -xwd | xwdtogif > %s
image/tiff; xv %s
image/jpeg; xv %s
video/mpeg; mpeg_play %s
message/external-body; $COMPOSE=xterm -e extcompose %s
application/postscript; lpr %s
application/pgp; xterm -e pgp %s 
text/richtext; xterm -e richtext %s
text/html; netscape file://localhost%s