.Open The MIME Multi-media Mail Format
.Source RFC 822(Mail layout),  RFC 1341(Character encoding)

. Macros
line::@#char->@#char= (_) eoln.
	|- For X:@#non(eoln), X.line::=X eoln.
.See http://www.csci.csusb.edu/dick/samples/comp.ASCII.text.html

.Open Message Format
message::=standard_mail_header mime_version.line (mime_type.line mime_encoding.line standard_mail_body ) & mime_formated_message.
mime_version::="MIME-Version: " N(digit) "." N(digit).
mime_type::="Content-Type: " type_subtype O(semicolon L(parameter, semicolon)).
|- mime_type==>"Content-Type: " type"/"subtype O(semicolon L(parameter, semicolon)).
mime_encoding::= word.

mime_formated_message::= part_message | multipart_message.
part_message::= |[(t,s):mime_type_subtype_pair~/1st("multipart")] ("Content-Type: " t "/" s).line mime_encoding.line part_in_format(t,s).

multi_part_message::= |[(t,s):mime_type_subtype_pair&/1st("multipart"), b: char^(1..70)] (t "/" s ";" "boundary=" b).line mime_encoding.line ( preamble b.line #( part b.line ) epilogue.
preamble and epilogue are ignored.
part::= implictly_typed_ASCII eoln | part_message.

mime_type_subtype_pair::= "text" >< ("plain" | "richtext") | "multipart"><("mixed" | "alternative" | "parallel" | "digest") | "message"><{"External-Body",...} | "image"><{...} | "audio" ><{...} | "video" ><{...} | "application" >< ("ODA" | "octet-stream" | "PostScript" | "ief" | "DCA-RFT" ).

type_subtype::=|[p:mime_type_subtype_pair](1st(p) "/" 2nd(p) )

type::=pre(mime_type_subtype_pair).
subtype::=post(mime_type_subtype_pair).

.Close Message Format
.Open text/richtext
.See http://www/dick/samples/comp.text.SGML.html

special_chars::= "<nl>" | "<np>" | "<lt>"
encoding::= whitspace+>ignored | "<nl>"+>eoln | "<np>"+>new_paragraph | "<lt>" +> less_than |+> Id.

richtext::= #( non(command) | special_chars ) |  |[ c:SGML.command ] ( c richtext SGML.negative(c) ).

|- SGML.command::= "<" (style | character_set | format ) ">",

|- SGML.negative_command="</" (style | character_set | format ) ">",

|- SGML.negative::command->negative_command= (1st) ! "/" ! (rest).

style::= "Bold" |  "Italic" | "Fixed" | "Bigger" | "Smaller".

character_set::= "US-ASCII" | "ISO-8859-X".
.Source ISO 8859-X
format::= "Underline" | "Center" | "FlushLeft" | "FlushRight" | "Indent" | "IndentRight" | "Outdent" | "Outdentright" | "SamePage" | "Subscript" | "Superscript" | "Heading" | "Footing" | "Excerpt" | "Paragraph" | "Signature" | "Comment" | "No-op".
.Close text/richtext

. Also See
A list of standard media types:
.See ftp://venera.isi.edu/in-notes/iana/assignments/media-types/