This section is for MIME users. The Section Some MIME Content Types and Subtypes -- which applies to MH, MH-E; and exmh -- lists some MIME content types and subtypes. The Section Syntax of MIME Draft Directives lists MIME directives; this is handy for MH, MH-E, and exmh users who are composing MIME messages. However, MH-E users are more likely to use the commands described in Section Adding Attachments of The MH-E Manual to insert MML (MIME Meta Language) tags.
There's a complete and up-to-date list of standard content types and subtypes available by anonymous FTP from ftp.isi.edu in the directory /in-notes/iana/assignments/media-types. The media-types directory contains a subdirectory for each content type; each of those directories contains a file for each content subtype. Note that there are some non-standard contents, like image/X-pbm, that are widely used.
text Content-type
Content-types
text/plain Text meant to be read by a person
text/richtext Obsolete; replaced by text/enriched
text/enriched Text with structure and font
information coded in plain ASCII
Parameters
; charset Character set
=us-ascii Default 7-bit ASCII (ANSI X3.4-1986)
=iso-8859-n ISO international character set
number n (1 thru 9)
=iso-2022-xx xx is JP for Japan (RFC 1468),
KR for Korea
=X-something Experimental, non-standard extension
message Content-type
message/rfc822 Body of message is structured in RFC 822
format (such as a forwarded message)
message/partial Message has been split into several parts
; id= Unique identifier for matching parts
; number= Location (1, 2, 3, etc.) of this part in all parts
; total= Total number of parts
message/external-body Data not included in message. May be cached
locally. Must have Content-ID: header field.
; access-type= How to access external body part
ftp File Transfer Protocol (RFC 959)
tftp Trivial File Transfer Protocol (RFC 783)
anon-ftp Anonymous FTP
local-file On recipient's local filesystem
afs Andrew filesystem
mail-server An email file server
X-something Experimental, non-standard extension
; expiration= (Optional) after this date, source data
may be deleted
; size= (Optional) size of data, in octets
; permission= (Optional)
read local cache will always be valid
read-write data may change; local cache may be invalid
application Content-type
application/octet-stream Uninterpreted data or data for an application
; type= General category of binary data
; padding= Number of bits of padding appended
application/oda Open Document Interchange Format (ODIF)
application/postscript Adobe PostScript
application/X-something Experimental, non-standard extension
audio Content-type
audio/basic u-law (telephone-quality) sound
image Content-type
image/jpeg JPEG-format image
image/gif GIF-format image
image/x-xwd X11 Window System Window Dump format (non-standard)
image/x-pbm Portable Bitmap format (non-standard)
image/X-something Experimental, non-standard extension
video Content-type
video/mpeg Video in MPEG format (ISO 11172 CD, May 1991)
video/X-something Experimental, non-standard extension
(may include synchronized audio)
multipart Content-type
multipart/mixed One or more content-types in a particular order
multipart/alternative Interchangeable parts, from simplest to most-faithful
multipart/digest Default content-type is message/rfc822
multipart/parallel Output all parts simultaneously, if possible
X-something Content-type
X-something/subtype Experimental, non-standard extension
The mhn(1) and mhbuild(1) manual pages have a precise explanation of the syntax of directives. This section is adapted from the mhn manual page.
A directive starts with a hash mark (#) as the first character of the line. A directive should fit on a single line unless you continue the directive by ending the line with a backslash (\). The tables in the Section Some MIME Content Types and Subtypes list some MIME types and subtypes.
Note that mhn will accept some invalid content-type directives like #<text/plane.
In the tables below, read down the first column for the parts of each directive. The second column tells how many of that part are needed: the value zero (0) means the part is not required. The third column describes the part. Type the parts you choose in the order given. As you saw at the top of the Section MIME Draft Directives, you can enter all the parts of a directive on one line -- or continue on another line, using a backslash.
Table 1. Type Directive for Files #
Part Quantity Description
#type/subtype 1 Content type and subtype
;attribute=value 0 or more Parameters for Content-Type:
(comment) 0 or 1 Comment for Content-Type:
<id> 0 or 1 Content-ID: to replace default
[description] 0 or 1 Content-Description:
filename 0 or 1 Content file to read. If none, use the
mhn-compose-type/subtype:
composition string.
Table 2. Type Directive for Text in Draft #<
Part Quantity Description
#<type/subtype 1 Content type and subtype
;attribute=value 0 or more Parameters for Content-Type:
(comment) 0 or 1 Comment for Content-Type:
[description] 0 or 1 Content-Description:
end of line 1 Directive must end before text begins
lines of text 1 or more Text for body part
# 0 or 1 Hash mark to signal end of body part
Table 3. External-type Directive #@
Part Quantity Description
#@type/subtype 1 Content type and subtype
;attribute=value 0 or more Parameters for mhn, mhbuild
(comment) 0 or 1 Comment for Content-Type:
<id> 0 or 1 Content-ID: to replace default
[description] 1 Content-Description:
;attribute=value 1 or more Parameters for external body part
Table 4. Message Directive: #forw
Part Quantity Description
#forw 1 Message-forwarding directive (creates
message/rfc822 or multipart/digest
content)
<id> 0 or 1 Content-ID: to replace default
[description] 1 Content-Description:
+folder 0 or 1 MH folder to read (default = current)
msgs 0 or more MH message numbers, ranges, sequences
(default = current message)
Table 5. Multiple Directives: #begin, #end
Part Quantity Description
#begin 1 Begin multipart content
<id> 0 or 1 Content-ID: to replace default
[description] 1 Content-Description:
alternative 1 Multipart content subtype
parallel " " "
something " " "
end of line 1 Directive must end before others
#directive(s) 1 or more Directives (and any text) for
included parts
#end 1 End multipart content