-.TH MHSHOW %manext1% "February 9, 2014" "%nmhversion%"
+.TH MHSHOW %manext1% "February 18, 2014" "%nmhversion%"
.\"
.\" %nmhwarning%
.\"
.PP
.RS 5
.nf
-.ta \w'%F 'u
-%a Insert parameters from Content-Type field
-%e exclusive execution
-%f Insert filename containing content
-%F %e, %f, and stdin is terminal not content
-%l display listing prior to displaying content
-%p %l, and ask for confirmation
-%s Insert content subtype
-%d Insert content description
-%% Insert the character %
+.ta \w'%F 'u
+%a Insert parameters from Content-Type field
+%{parameter} Insert the parameter value from the Content-Type field
+%e exclusive execution
+%f Insert filename containing content
+%F %e, %f, and stdin is terminal not content
+%l display listing prior to displaying content
+%p %l, and ask for confirmation
+%s Insert content subtype
+%d Insert content description
+%% Insert the character %
.fi
.RE
.PP
.B mhshow
to wrap things up immediately.
.PP
+The {parameter} escape is typically used in a command line argument
+that should only be present if it has a non-null value. Its value
+will be wrapped with single quotes if the escape is not so wrapped.
+Shell parameter expansion can construct the argument only when it is
+non-null, e.g.,
+.PP
+.RS 5
+.nf
+mhshow-show-text/html: charset=%{charset};
+ w3m ${charset:+-I $charset} -T text/html %F
+.fi
+.RE
+.PP
+That example also shows the use of indentation to signify continuation:
+the two text lines combine to form a single entry.
+.PP
Note that if the content being displayed is multipart, but not one of
the subtypes listed above, then the f- and F-escapes expand to multiple
filenames, one for each subordinate content. Further, stdin is not
.PP
.RS 5
.nf
-mhshow-show-text/plain: %pmoreproc '%F'
-mhshow-show-message/rfc822: %pshow -file '%F'
+mhshow-show-text/plain: %pmoreproc %F
+mhshow-show-message/rfc822: %pshow -file %F
.fi
.RE
.PP
.RS 5
.nf
mhshow-show-audio/basic: raw2audio 2>/dev/null | play
-mhshow-show-image: xv '%f'
+mhshow-show-image: xv %f
mhshow-show-application/PostScript: lpr -Pps
.fi
.RE
.PP
-Note that when using the f- or F-escape, it's a good idea to use
-single-quotes around the escape. This prevents misinterpretation by
-the shell of any funny characters that might be present in the filename.
+If an f- or F-escape is not quoted with single quotes, its expansion
+will be wrapped with single quotes.
.PP
Finally,
.B mhshow