-The \*(lqexternal-type\*(rq directives are used to provide a MIME
-reference to a content, rather than enclosing the contents itself
-(for instance, by specifying an ftp site). Hence, instead of
-providing a filename as with the type directives, external-parameters
-are supplied. These look like regular parameters, so they must be
-separated accordingly. For example,
-.PP
-.RS 5
-.nf
-#@application/octet-stream; \\
- type=tar; \\
- conversions=compress \\
- [this is the nmh distribution] \\
- {application; filename="nmh.tar.gz"} \\
- name="nmh.tar.gz"; \\
- directory="/pub/nmh"; \\
- site="ftp.math.gatech.edu"; \\
- access-type=anon-ftp; \\
- mode="image"
-.fi
-.RE
-.PP
-You must give a description string to separate the content parameters
-from the external-parameters (although this string may be empty).
-This description string is specified by enclosing it within
-\*(lq[]\*(rq. A disposition string, to appear in a
-\*(lqContent-Disposition\*(rq header, may appear in the optional
-\*(lq{}\*(rq.
-.PP
-These parameters are of the form:
-.PP
-.RS 5
-.nf
-.ta \w'access-type= 'u
-access-type= usually \fIanon-ftp\fR or \fImail-server\fR
-name= filename
-permission= read-only or read-write
-site= hostname
-directory= directoryname (optional)
-mode= usually \fIascii\fR or \fIimage\fR (optional)
-size= number of octets
-server= mailbox
-subject= subject to send
-body= command to send for retrieval
-.fi
-.RE
-.PP
-The \*(lqmessage\*(rq directive (#forw) is used to specify a message or