+If the
+.B \-disposition
+switch is present, then the listing will show any relevant information from
+the \*(lqContent-Disposition\*(rq header.
+.SS "Simplified Attachment Interface"
+For users who wish to simply attach files to text content,
+.B mhbuild
+will scan the composition file for \*(lqAttach\*(rq headers.
+An
+\*(lqAttach\*(rq header contains a filename that will be appended to the
+message using normal MIME encapsulation rules.
+One filename is allowed
+per \*(lqAttach\*(rq header, but multiple \*(lqAttach\*(rq headers are
+allowed ber composition file.
+.PP
+These files will be appended after any other MIME content, including any
+content specified by
+.B mhbuild
+directives (see below).
+See
+.IR send (1)
+for more details.
+.PP
+By default, the Content-Disposition will be \*(lqattachment\*(rq.
+.B mhbuild
+looks for user profile and
+.I mhn.defaults
+entries of the form
+.PP
+.RS 5
+.BI mhbuild-disposition- type / subtype
+.RE
+or
+.RS 5
+.BI mhbuild-disposition- type
+.RE
+.PP
+to supply the disposition value.
+The only supported values are
+\*(lqattachment\*(rq
+and
+\*(lqinline\*(rq.
+.SS "Convert Interface"
+The convert interface is a powerful mechanism that supports
+replying to MIME messages.
+These placeholders are used in the following
+description:
+.RS 5
+.TP 15
+.PD 0
+TYPE
+content type/subtype
+.TP
+CONVERTER
+external program, and any fixed arguments, to convert content, such as
+from a request to a reply
+.TP
+ARGSTRING
+arguments to pass from
+.B repl
+to
+.I CONVERTER
+.TP
+FILE
+full path of message being replied to
+.PD
+.RE
+.PP
+.RE
+The convert support is based on pseudoheaders of the form
+.PP
+.RS 5
+.nf
+.BI Nmh-mhbuild-file- TYPE : \0FILE
+.BI Nmh-mhbuild-args- TYPE : \0ARGSTRING
+.fi
+.RE
+.PP
+in the draft.
+For each such pseudoheader, mhbuild looks in the
+profile and
+.I mhn.defaults
+for this corresponding
+.I TYPE
+entry to find the
+converter that supports it:
+.PP
+.RS 5
+.BI mhbuild-convert- TYPE : \0CONVERTER
+.RE
+.PP
+It's a fatal error if no such entry is found for
+.IR TYPE .
+An empty
+entry, e.g.,
+.PP
+.RS 5
+.B mhbuild-convert-text/html:
+.RE
+.PP
+excludes parts of that
+.I TYPE
+from the draft.