\&...
.RB [ \-form
.IR formfile ]
-.RB [ \-rcache
-.IR policy ]
-.RB [ \-wcache
-.IR policy ]
.RB [ \-version ]
.RB [ \-help ]
.ad
.PP
If none of these apply, then
.B mhshow
-will check to see if the message
-has an application/octet-stream content with parameter \*(lqtype=tar\*(rq.
-If so,
-.B mhshow
-will use an appropriate command. If not,
-.B mhshow
will complain.
.PP
Example entries might be:
.PP
The program should terminate with an exit status of zero if the
retrieval is successful, and a non-zero exit status otherwise.
-.SS "The Content Cache"
-When
-.B mhshow
-encounters an external content containing a
-\*(lqContent-ID:\*(rq field, and if the content allows caching, then
-depending on the caching behavior of
-.BR mhshow ,
-the content might be read from or written to a cache.
-.PP
-The caching behavior of
-.B mhshow
-is controlled with the
-.B \-rcache
-and
-.B \-wcache
-switches, which define the policy for reading from,
-and writing to, the cache, respectively. One of four policies may be
-specified: \*(lqpublic\*(rq, indicating that
-.B mhshow
-should make use
-of a publically-accessible content cache; \*(lqprivate\*(rq, indicating
-that
-.B mhshow
-should make use of the user's private content cache;
-\*(lqnever\*(rq, indicating that
-.B mhshow
-should never make use of
-caching; and, \*(lqask\*(rq, indicating that
-.B mhshow
-should ask the user.
-.PP
-There are two directories where contents may be cached: the profile entry
-\*(lqnmh-cache\*(rq names a directory containing world-readable contents, and,
-the profile entry \*(lqnmh-private-cache\*(rq names a directory containing
-private contents. The former should be an absolute (rooted) directory
-name.
-.PP
-For example,
-.PP
-.RS 5
-nmh-cache: /tmp
-.RE
-.PP
-might be used if you didn't care that the cache got wiped after each
-reboot of the system. The private cache is interpreted relative to the user's
-mail storage, if not rooted, e.g.,
-.PP
-.RS 5
-nmh-private-cache: .cache
-.RE
-.PP
-(which is the default value).
.SS "User Environment"
Because the display environment in which
.B mhshow
^Current\-Folder:~^To find the default current folder
^Unseen\-Sequence:~^To name sequences denoting unseen messages
^nmh-access-ftp:~^Program to retrieve contents via FTP
-^nmh-cache~^Public directory to store cached external contents
-^nmh-private-cache~^Personal directory to store cached external contents
^mhshow-charset-<charset>~^Template for environment to render character sets
^mhshow-show-<type>*~^Template for displaying contents
^Pager:~^Default program to display text/plain content
.RB ` +folder "' defaults to the current folder"
.RB ` msgs "' defaults to cur"
.RB ` \-form \ mhl.headers'
-.RB ` \-rcache \ ask'
.RB ` \-noverbose '
-.RB ` \-wcache \ ask'
.fi
.SH CONTEXT