This is emacs-mime, produced by makeinfo version 4.0 from
emacs-mime.texi.

INFO-DIR-SECTION The Emacs editor and associated tools
START-INFO-DIR-ENTRY
* Emacs MIME: (emacs-mime).	The MIME de/composition library.
END-INFO-DIR-ENTRY

   This file documents the Emacs MIME interface functionality.

   Copyright (C) 1998,99,2000 Free Software Foundation, Inc.

   Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover texts being "A GNU Manual",
and with the Back-Cover Texts as in (a) below.  A copy of the license
is included in the section entitled "GNU Free Documentation License" in
the Emacs manual.

   (a) The FSF's Back-Cover Text is: "You have freedom to copy and
modify this GNU Manual, like GNU software.  Copies published by the Free
Software Foundation raise funds for GNU development."

   This document is part of a collection distributed under the GNU Free
Documentation License.  If you want to distribute this document
separately from the collection, you can do so by adding a copy of the
license to the document, as described in section 6 of the license.


File: emacs-mime,  Node: Top,  Next: Interface Functions,  Up: (dir)

Emacs MIME
**********

   This manual documents the libraries used to compose and display MIME
messages.

   This is not a manual meant for users; it's a manual directed at
people who want to write functions and commands that manipulate MIME
elements.

   MIME is short for "Multipurpose Internet Mail Extensions".  This
standard is documented in a number of RFCs; mainly RFC2045 (Format of
Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message
Header Extensions for Non-ASCII Text), RFC2048 (Registration
Procedures), RFC2049 (Conformance Criteria and Examples).  It is highly
recommended that anyone who intends writing MIME-compliant software
read at least RFC2045 and RFC2047.

* Menu:

* Interface Functions::   An abstraction over the basic functions.
* Basic Functions::       Utility and basic parsing functions.
* Decoding and Viewing::  A framework for decoding and viewing.
* Composing::             MML; a language for describing MIME parts.
* Standards::             A summary of RFCs and working documents used.
* Index::                 Function and variable index.


File: emacs-mime,  Node: Interface Functions,  Next: Basic Functions,  Prev: Top,  Up: Top

Interface Functions
*******************

   The `mail-parse' library is an abstraction over the actual low-level
libraries that are described in the next chapter.

   Standards change, and so programs have to change to fit in the new
mold.  For instance, RFC2045 describes a syntax for the `Content-Type'
header that only allows ASCII characters in the parameter list.
RFC2231 expands on RFC2045 syntax to provide a scheme for continuation
headers and non-ASCII characters.

   The traditional way to deal with this is just to update the library
functions to parse the new syntax.  However, this is sometimes the wrong
thing to do.  In some instances it may be vital to be able to understand
both the old syntax as well as the new syntax, and if there is only one
library, one must choose between the old version of the library and the
new version of the library.

   The Emacs MIME library takes a different tack.  It defines a series
of low-level libraries (`rfc2047.el', `rfc2231.el' and so on) that
parses strictly according to the corresponding standard.  However,
normal programs would not use the functions provided by these libraries
directly, but instead use the functions provided by the `mail-parse'
library.  The functions in this library are just aliases to the
corresponding functions in the latest low-level libraries.  Using this
scheme, programs get a consistent interface they can use, and library
developers are free to create write code that handles new standards.

   The following functions are defined by this library:

`mail-header-parse-content-type'
     Parse a `Content-Type' header and return a list on the following
     format:

          ("type/subtype"
           (attribute1 . value1)
           (attribute2 . value2)
           ...)

     Here's an example:

          (mail-header-parse-content-type
           "image/gif; name=\"b980912.gif\"")
          => ("image/gif" (name . "b980912.gif"))

`mail-header-parse-content-disposition'
     Parse a `Content-Disposition' header and return a list on the same
     format as the function above.

`mail-content-type-get'
     Takes two parameters--a list on the format above, and an attribute.
     Returns the value of the attribute.

          (mail-content-type-get
           '("image/gif" (name . "b980912.gif")) 'name)
          => "b980912.gif"

`mail-header-encode-parameter'
     Takes a parameter string and returns an encoded version of the
     string.  This is used for parameters in headers like
     `Content-Type' and `Content-Disposition'.

`mail-header-remove-comments'
     Return a comment-free version of a header.

          (mail-header-remove-comments
           "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
          => "Gnus/5.070027  "

`mail-header-remove-whitespace'
     Remove linear white space from a header.  Space inside quoted
     strings and comments is preserved.

          (mail-header-remove-whitespace
           "image/gif; name=\"Name with spaces\"")
          => "image/gif;name=\"Name with spaces\""

`mail-header-get-comment'
     Return the last comment in a header.

          (mail-header-get-comment
           "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
          => "Finnish Landrace"

`mail-header-parse-address'
     Parse an address and return a list containing the mailbox and the
     plaintext name.

          (mail-header-parse-address
           "Hrvoje Niksic <hniksic@srce.hr>")
          => ("hniksic@srce.hr" . "Hrvoje Niksic")

`mail-header-parse-addresses'
     Parse a string with list of addresses and return a list of
     elements like the one described above.

          (mail-header-parse-addresses
           "Hrvoje Niksic <hniksic@srce.hr>, Steinar Bang <sb@metis.no>")
          => (("hniksic@srce.hr" . "Hrvoje Niksic")
               ("sb@metis.no" . "Steinar Bang"))

`mail-header-parse-date'
     Parse a date string and return an Emacs time structure.

`mail-narrow-to-head'
     Narrow the buffer to the header section of the buffer.  Point is
     placed at the beginning of the narrowed buffer.

`mail-header-narrow-to-field'
     Narrow the buffer to the header under point.

`mail-encode-encoded-word-region'
     Encode the non-ASCII words in the region.  For instance, `Naïve'
     is encoded as `=?iso-8859-1?q?Na=EFve?='.

`mail-encode-encoded-word-buffer'
     Encode the non-ASCII words in the current buffer.  This function is
     meant to be called narrowed to the headers of a message.

`mail-encode-encoded-word-string'
     Encode the words that need encoding in a string, and return the
     result.

          (mail-encode-encoded-word-string
           "This is naïve, baby")
          => "This is =?iso-8859-1?q?na=EFve,?= baby"

`mail-decode-encoded-word-region'
     Decode the encoded words in the region.

`mail-decode-encoded-word-string'
     Decode the encoded words in the string and return the result.

          (mail-decode-encoded-word-string
           "This is =?iso-8859-1?q?na=EFve,?= baby")
          => "This is naïve, baby"

   Currently, `mail-parse' is an abstraction over `ietf-drums',
`rfc2047', `rfc2045' and `rfc2231'.  These are documented in the
subsequent sections.


File: emacs-mime,  Node: Basic Functions,  Next: Decoding and Viewing,  Prev: Interface Functions,  Up: Top

Basic Functions
***************

   This chapter describes the basic, ground-level functions for parsing
and handling.  Covered here is parsing `From' lines, removing comments
from header lines, decoding encoded words, parsing date headers and so
on.  High-level functionality is dealt with in the next chapter (*note
Decoding and Viewing::).

* Menu:

* rfc2045::      Encoding `Content-Type' headers.
* rfc2231::      Parsing `Content-Type' headers.
* ietf-drums::   Handling mail headers defined by RFC822bis.
* rfc2047::      En/decoding encoded words in headers.
* time-date::    Functions for parsing dates and manipulating time.
* qp::           Quoted-Printable en/decoding.
* base64::       Base64 en/decoding.
* binhex::       Binhex decoding.
* uudecode::     Uuencode decoding.
* rfc1843::      Decoding HZ-encoded text.
* mailcap::      How parts are displayed is specified by the `.mailcap' file


File: emacs-mime,  Node: rfc2045,  Next: rfc2231,  Up: Basic Functions

rfc2045
=======

   RFC2045 is the "main" MIME document, and as such, one would imagine
that there would be a lot to implement.  But there isn't, since most of
the implementation details are delegated to the subsequent RFCs.

   So `rfc2045.el' has only a single function:

`rfc2045-encode-string'
     Takes a parameter and a value and returns a `PARAM=VALUE' string.
     VALUE will be quoted if there are non-safe characters in it.


File: emacs-mime,  Node: rfc2231,  Next: ietf-drums,  Prev: rfc2045,  Up: Basic Functions

rfc2231
=======

   RFC2231 defines a syntax for the `Content-Type' and
`Content-Disposition' headers.  Its snappy name is "MIME Parameter
Value and Encoded Word Extensions: Character Sets, Languages, and
Continuations".

   In short, these headers look something like this:

     Content-Type: application/x-stuff;
      title*0*=us-ascii'en'This%20is%20even%20more%20;
      title*1*=%2A%2A%2Afun%2A%2A%2A%20;
      title*2="isn't it!"

   They usually aren't this bad, though.

   The following functions are defined by this library:

`rfc2231-parse-string'
     Parse a `Content-Type' header and return a list describing its
     elements.

          (rfc2231-parse-string
           "application/x-stuff;
           title*0*=us-ascii'en'This%20is%20even%20more%20;
           title*1*=%2A%2A%2Afun%2A%2A%2A%20;
           title*2=\"isn't it!\"")
          => ("application/x-stuff"
              (title . "This is even more ***fun*** isn't it!"))

`rfc2231-get-value'
     Takes one of the lists on the format above and returns the value
     of the specified attribute.

`rfc2231-encode-string'
     Encode a parameter in headers likes `Content-Type' and
     `Content-Disposition'.


File: emacs-mime,  Node: ietf-drums,  Next: rfc2047,  Prev: rfc2231,  Up: Basic Functions

ietf-drums
==========

   "drums" is an IETF working group that is working on the replacement
for RFC822.

   The functions provided by this library include:

`ietf-drums-remove-comments'
     Remove the comments from the argument and return the results.

`ietf-drums-remove-whitespace'
     Remove linear white space from the string and return the results.
     Spaces inside quoted strings and comments are left untouched.

`ietf-drums-get-comment'
     Return the last most comment from the string.

`ietf-drums-parse-address'
     Parse an address string and return a list that contains the
     mailbox and the plain text name.

`ietf-drums-parse-addresses'
     Parse a string that contains any number of comma-separated
     addresses and return a list that contains mailbox/plain text pairs.

`ietf-drums-parse-date'
     Parse a date string and return an Emacs time structure.

`ietf-drums-narrow-to-header'
     Narrow the buffer to the header section of the current buffer.


File: emacs-mime,  Node: rfc2047,  Next: time-date,  Prev: ietf-drums,  Up: Basic Functions

rfc2047
=======

   RFC2047 (Message Header Extensions for Non-ASCII Text) specifies how
non-ASCII text in headers are to be encoded.  This is actually rather
complicated, so a number of variables are necessary to tweak what this
library does.

   The following variables are tweakable:

`rfc2047-default-charset'
     Characters in this charset should not be decoded by this library.
     This defaults to `iso-8859-1'.

`rfc2047-header-encoding-list'
     This is an alist of header / encoding-type pairs.  Its main
     purpose is to prevent encoding of certain headers.

     The keys can either be header regexps, or `t'.

     The values can be either `nil', in which case the header(s) in
     question won't be encoded, or `mime', which means that they will be
     encoded.

`rfc2047-charset-encoding-alist'
     RFC2047 specifies two forms of encoding--`Q' (a
     Quoted-Printable-like encoding) and `B' (base64).  This alist
     specifies which charset should use which encoding.

`rfc2047-encoding-function-alist'
     This is an alist of encoding / function pairs.  The encodings are
     `Q', `B' and `nil'.

`rfc2047-q-encoding-alist'
     The `Q' encoding isn't quite the same for all headers.  Some
     headers allow a narrower range of characters, and that is what this
     variable is for.  It's an alist of header regexps / allowable
     character ranges.

`rfc2047-encoded-word-regexp'
     When decoding words, this library looks for matches to this regexp.

   Those were the variables, and these are this functions:

`rfc2047-narrow-to-field'
     Narrow the buffer to the header on the current line.

`rfc2047-encode-message-header'
     Should be called narrowed to the header of a message.  Encodes
     according to `rfc2047-header-encoding-alist'.

`rfc2047-encode-region'
     Encodes all encodable words in the region specified.

`rfc2047-encode-string'
     Encode a string and return the results.

`rfc2047-decode-region'
     Decode the encoded words in the region.

`rfc2047-decode-string'
     Decode a string and return the results.


File: emacs-mime,  Node: time-date,  Next: qp,  Prev: rfc2047,  Up: Basic Functions

time-date
=========

   While not really a part of the MIME library, it is convenient to
document this library here.  It deals with parsing `Date' headers and
manipulating time.  (Not by using tesseracts, though, I'm sorry to say.)

   These functions convert between five formats: A date string, an Emacs
time structure, a decoded time list, a second number, and a day number.

   The functions have quite self-explanatory names, so the following
just gives an overview of which functions are available.

     (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
     => (54 21 12 12 9 1998 6 nil 7200)
     
     (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
     => (13818 19266)
     
     (time-to-seconds '(13818 19266))
     => 905595714.0
     
     (seconds-to-time 905595714.0)
     => (13818 19266 0)
     
     (time-to-day '(13818 19266))
     => 729644
     
     (days-to-time 729644)
     => (961933 65536)
     
     (time-since '(13818 19266))
     => (0 430)
     
     (time-less-p '(13818 19266) '(13818 19145))
     => nil
     
     (subtract-time '(13818 19266) '(13818 19145))
     => (0 121)
     
     (days-between "Sat Sep 12 12:21:54 1998 +0200"
                   "Sat Sep 07 12:21:54 1998 +0200")
     => 5
     
     (date-leap-year-p 2000)
     => t
     
     (time-to-day-in-year '(13818 19266))
     => 255

   And finally, we have `safe-date-to-time', which does the same as
`date-to-time', but returns a zero time if the date is syntactically
malformed.


File: emacs-mime,  Node: qp,  Next: base64,  Prev: time-date,  Up: Basic Functions

qp
==

   This library deals with decoding and encoding Quoted-Printable text.

   Very briefly explained, qp encoding means translating all 8-bit
characters (and lots of control characters) into things that look like
`=EF'; that is, an equal sign followed by the byte encoded as a hex
string.

   The following functions are defined by the library:

`quoted-printable-decode-region'
     QP-decode all the encoded text in the specified region.

`quoted-printable-decode-string'
     Decode the QP-encoded text in a string and return the results.

`quoted-printable-encode-region'
     QP-encode all the encodable characters in the specified region.
     The third optional parameter FOLD specifies whether to fold long
     lines.  (Long here means 72.)

`quoted-printable-encode-string'
     QP-encode all the encodable characters in a string and return the
     results.


File: emacs-mime,  Node: base64,  Next: binhex,  Prev: qp,  Up: Basic Functions

base64
======

   Base64 is an encoding that encodes three bytes into four characters,
thereby increasing the size by about 33%.  The alphabet used for
encoding is very resistant to mangling during transit.

   The following functions are defined by this library:

`base64-encode-region'
     base64 encode the selected region.  Return the length of the
     encoded text.  Optional third argument NO-LINE-BREAK means do not
     break long lines into shorter lines.

`base64-encode-string'
     base64 encode a string and return the result.

`base64-decode-region'
     base64 decode the selected region.  Return the length of the
     decoded text.  If the region can't be decoded, return `nil' and
     don't modify the buffer.

`base64-decode-string'
     base64 decode a string and return the result.  If the string can't
     be decoded, `nil' is returned.


File: emacs-mime,  Node: binhex,  Next: uudecode,  Prev: base64,  Up: Basic Functions

binhex
======

   `binhex' is an encoding that originated in Macintosh environments.
The following function is supplied to deal with these:

`binhex-decode-region'
     Decode the encoded text in the region.  If given a third
     parameter, only decode the `binhex' header and return the filename.


File: emacs-mime,  Node: uudecode,  Next: rfc1843,  Prev: binhex,  Up: Basic Functions

uudecode
========

   `uuencode' is probably still the most popular encoding of binaries
used on Usenet, although `base64' rules the mail world.

   The following function is supplied by this package:

`uudecode-decode-region'
     Decode the text in the region.


File: emacs-mime,  Node: rfc1843,  Next: mailcap,  Prev: uudecode,  Up: Basic Functions

rfc1843
=======

   RFC1843 deals with mixing Chinese and ASCII characters in messages.
In essence, RFC1843 switches between ASCII and Chinese by doing this:

     This sentence is in ASCII.
     The next sentence is in GB.~{<:Ky2;S{#,NpJ)l6HK!#~}Bye.

   Simple enough, and widely used in China.

   The following functions are available to handle this encoding:

`rfc1843-decode-region'
     Decode HZ-encoded text in the region.

`rfc1843-decode-string'
     Decode a HZ-encoded string and return the result.


File: emacs-mime,  Node: mailcap,  Prev: rfc1843,  Up: Basic Functions

mailcap
=======

   The `~/.mailcap' file is parsed by most MIME-aware message handlers
and describes how elements are supposed to be displayed.  Here's an
example file:

     image/*; gimp -8 %s
     audio/wav; wavplayer %s

   This says that all image files should be displayed with `gimp', and
that realaudio files should be played by `rvplayer'.

   The `mailcap' library parses this file, and provides functions for
matching types.

`mailcap-mime-data'
     This variable is an alist of alists containing backup viewing
     rules.

   Interface functions:

`mailcap-parse-mailcaps'
     Parse the `~/.mailcap' file.

`mailcap-mime-info'
     Takes a MIME type as its argument and returns the matching viewer.


File: emacs-mime,  Node: Decoding and Viewing,  Next: Composing,  Prev: Basic Functions,  Up: Top

Decoding and Viewing
********************

   This chapter deals with decoding and viewing MIME messages on a
higher level.

   The main idea is to first analyze a MIME article, and then allow
other programs to do things based on the list of "handles" that are
returned as a result of this analysis.

* Menu:

* Dissection::     Analyzing a MIME message.
* Handles::        Handle manipulations.
* Display::        Displaying handles.
* Customization::  Variables that affect display.
* New Viewers::    How to write your own viewers.


File: emacs-mime,  Node: Dissection,  Next: Handles,  Up: Decoding and Viewing

Dissection
==========

   The `mm-dissect-buffer' is the function responsible for dissecting a
MIME article.  If given a multipart message, it will recursively
descend the message, following the structure, and return a tree of MIME
handles that describes the structure of the message.


File: emacs-mime,  Node: Handles,  Next: Display,  Prev: Dissection,  Up: Decoding and Viewing

Handles
=======

   A MIME handle is a list that fully describes a MIME component.

   The following macros can be used to access elements in a handle:

`mm-handle-buffer'
     Return the buffer that holds the contents of the undecoded MIME
     part.

`mm-handle-type'
     Return the parsed `Content-Type' of the part.

`mm-handle-encoding'
     Return the `Content-Transfer-Encoding' of the part.

`mm-handle-undisplayer'
     Return the object that can be used to remove the displayed part
     (if it has been displayed).

`mm-handle-set-undisplayer'
     Set the undisplayer object.

`mm-handle-disposition'
     Return the parsed `Content-Disposition' of the part.

`mm-handle-disposition'
     Return the description of the part.

`mm-get-content-id'
     Returns the handle(s) referred to by `Content-ID'.


File: emacs-mime,  Node: Display,  Next: Customization,  Prev: Handles,  Up: Decoding and Viewing

Display
=======

   Functions for displaying, removing and saving.

`mm-display-part'
     Display the part.

`mm-remove-part'
     Remove the part (if it has been displayed).

`mm-inlinable-p'
     Say whether a MIME type can be displayed inline.

`mm-automatic-display-p'
     Say whether a MIME type should be displayed automatically.

`mm-destroy-part'
     Free all resources occupied by a part.

`mm-save-part'
     Offer to save the part in a file.

`mm-pipe-part'
     Offer to pipe the part to some process.

`mm-interactively-view-part'
     Prompt for a mailcap method to use to view the part.


File: emacs-mime,  Node: Customization,  Next: New Viewers,  Prev: Display,  Up: Decoding and Viewing

Customization
=============

`mm-inline-media-tests'
     This is an alist where the key is a MIME type, the second element
     is a function to display the part "inline" (i.e., inside Emacs),
     and the third element is a form to be `eval'ed to say whether the
     part can be displayed inline.

     This variable specifies whether a part _can_ be displayed inline,
     and, if so, how to do it.  It does not say whether parts are
     _actually_ displayed inline.

`mm-inlined-types'
     This, on the other hand, says what types are to be displayed
     inline, if they satisfy the conditions set by the variable above.
     It's a list of MIME media types.

`mm-automatic-display'
     This is a list of types that are to be displayed "automatically",
     but only if the above variable allows it.  That is, only inlinable
     parts can be displayed automatically.

`mm-attachment-override-types'
     Some MIME agents create parts that have a content-disposition of
     `attachment'.  This variable allows overriding that disposition and
     displaying the part inline.  (Note that the disposition is only
     overridden if we are able to, and want to, display the part
     inline.)

`mm-discouraged-alternatives'
     List of MIME types that are discouraged when viewing
     `multipart/alternative'.  Viewing agents are supposed to view the
     last possible part of a message, as that is supposed to be the
     richest.  However, users may prefer other types instead, and this
     list says what types are most unwanted.  If, for instance,
     `text/html' parts are very unwanted, and `text/richtech' parts are
     somewhat unwanted, then the value of this variable should be set
     to:

          ("text/html" "text/richtext")

`mm-inline-large-images-p'
     When displaying inline images that are larger than the window,
     XEmacs does not enable scrolling, which means that you cannot see
     the whole image.  To prevent this, the library tries to determine
     the image size before displaying it inline, and if it doesn't fit
     the window, the library will display it externally (e.g. with
     `ImageMagick' or `xv').  Setting this variable to `t' disables
     this check and makes the library display all inline images as
     inline, regardless of their size.

`mm-inline-override-p'
     `mm-inlined-types' may include regular expressions, for example to
     specify that all `text/.*' parts be displayed inline.  If a user
     prefers to have a type that matches such a regular expression be
     treated as an attachment, that can be accomplished by setting this
     variable to a list containing that type.  For example assuming
     `mm-inlined-types' includes `text/.*', then including `text/html'
     in this variable will cause `text/html' parts to be treated as
     attachments.


File: emacs-mime,  Node: New Viewers,  Prev: Customization,  Up: Decoding and Viewing

New Viewers
===========

   Here's an example viewer for displaying `text/enriched' inline:

     (defun mm-display-enriched-inline (handle)
       (let (text)
         (with-temp-buffer
           (mm-insert-part handle)
           (save-window-excursion
             (enriched-decode (point-min) (point-max))
             (setq text (buffer-string))))
         (mm-insert-inline handle text)))

   We see that the function takes a MIME handle as its parameter.  It
then goes to a temporary buffer, inserts the text of the part, does some
work on the text, stores the result, goes back to the buffer it was
called from and inserts the result.

   The two important helper functions here are `mm-insert-part' and
`mm-insert-inline'.  The first function inserts the text of the handle
in the current buffer.  It handles charset and/or content transfer
decoding.  The second function just inserts whatever text you tell it
to insert, but it also sets things up so that the text can be
"undisplayed' in a convenient manner.


File: emacs-mime,  Node: Composing,  Next: Standards,  Prev: Decoding and Viewing,  Up: Top

Composing
*********

   Creating a MIME message is boring and non-trivial.  Therefore, a
library called `mml' has been defined that parses a language called MML
(MIME Meta Language) and generates MIME messages.

   The main interface function is `mml-generate-mime'.  It will examine
the contents of the current (narrowed-to) buffer and return a string
containing the MIME message.

* Menu:

* Simple MML Example::             An example MML document.
* MML Definition::                 All valid MML elements.
* Advanced MML Example::           Another example MML document.
* Charset Translation::            How charsets are mapped from MULE to MIME.
* Conversion::                     Going from MIME to MML and vice versa.


File: emacs-mime,  Node: Simple MML Example,  Next: MML Definition,  Up: Composing

Simple MML Example
==================

   Here's a simple `multipart/alternative':

     <#multipart type=alternative>
     This is a plain text part.
     <#part type=text/enriched>
     <center>This is a centered enriched part</center>
     <#/multipart>

   After running this through `mml-generate-mime', we get this:

     Content-Type: multipart/alternative; boundary="=-=-="
     
     
     --=-=-=
     
     
     This is a plain text part.
     
     --=-=-=
     Content-Type: text/enriched
     
     
     <center>This is a centered enriched part</center>
     
     --=-=-=--


File: emacs-mime,  Node: MML Definition,  Next: Advanced MML Example,  Prev: Simple MML Example,  Up: Composing

MML Definition
==============

   The MML language is very simple.  It looks a bit like an SGML
application, but it's not.

   The main concept of MML is the "part".  Each part can be of a
different type or use a different charset.  The way to delineate a part
is with a `<#part ...>' tag.  Multipart parts can be introduced with
the `<#multipart ...>' tag.  Parts are ended by the `<#/part>' or
`<#/multipart>' tags.  Parts started with the `<#part ...>' tags are
also closed by the next open tag.

   There's also the `<#external ...>' tag.  These introduce
`external/message-body' parts.

   Each tag can contain zero or more parameters on the form
`parameter=value'.  The values may be enclosed in quotation marks, but
that's not necessary unless the value contains white space.  So
`filename=/home/user/#hello$^yes' is perfectly valid.

   The following parameters have meaning in MML; parameters that have no
meaning are ignored.  The MML parameter names are the same as the MIME
parameter names; the things in the parentheses say which header it will
be used in.

`type'
     The MIME type of the part (`Content-Type').

`filename'
     Use the contents of the file in the body of the part
     (`Content-Disposition').

`charset'
     The contents of the body of the part are to be encoded in the
     character set speficied (`Content-Type').

`name'
     Might be used to suggest a file name if the part is to be saved to
     a file (`Content-Type').

`disposition'
     Valid values are `inline' and `attachment' (`Content-Disposition').

`encoding'
     Valid values are `7bit', `8bit', `quoted-printable' and `base64'
     (`Content-Transfer-Encoding').

`description'
     A description of the part (`Content-Description').

`creation-date'
     RFC822 date when the part was created (`Content-Disposition').

`modification-date'
     RFC822 date when the part was modified (`Content-Disposition').

`read-date'
     RFC822 date when the part was read (`Content-Disposition').

`size'
     The size (in octets) of the part (`Content-Disposition').

   Parameters for `application/octet-stream':

`type'
     Type of the part; informal--meant for human readers
     (`Content-Type').

   Parameters for `message/external-body':

`access-type'
     A word indicating the supported access mechanism by which the file
     may be obtained.  Values include `ftp', `anon-ftp', `tftp',
     `localfile', and `mailserver'.  (`Content-Type'.)

`expiration'
     The RFC822 date after which the file may no longer be fetched.
     (`Content-Type'.)

`size'
     The size (in octets) of the file.  (`Content-Type'.)

`permission'
     Valid values are `read' and `read-write' (`Content-Type').


File: emacs-mime,  Node: Advanced MML Example,  Next: Charset Translation,  Prev: MML Definition,  Up: Composing

Advanced MML Example
====================

   Here's a complex multipart message.  It's a `multipart/mixed' that
contains many parts, one of which is a `multipart/alternative'.

     <#multipart type=mixed>
     <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
     <#multipart type=alternative>
     This is a plain text part.
     <#part type=text/enriched name=enriched.txt>
     <center>This is a centered enriched part</center>
     <#/multipart>
     This is a new plain text part.
     <#part disposition=attachment>
     This plain text part is an attachment.
     <#/multipart>

   And this is the resulting MIME message:

     Content-Type: multipart/mixed; boundary="=-=-="
     
     
     --=-=-=
     
     
     
     --=-=-=
     Content-Type: image/jpeg;
      filename="~/rms.jpg"
     Content-Disposition: inline;
      filename="~/rms.jpg"
     Content-Transfer-Encoding: base64
     
     /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
     Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
     AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
     BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
     RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
     qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
     AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
     AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
     sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
     2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
     5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
     L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
     34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
     tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
     7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
     pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
     jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
     
     --=-=-=
     Content-Type: multipart/alternative; boundary="==-=-="
     
     
     --==-=-=
     
     
     This is a plain text part.
     
     --==-=-=
     Content-Type: text/enriched;
      name="enriched.txt"
     
     
     <center>This is a centered enriched part</center>
     
     --==-=-=--
     
     --=-=-=
     
     This is a new plain text part.
     
     --=-=-=
     Content-Disposition: attachment
     
     
     This plain text part is an attachment.
     
     --=-=-=--


File: emacs-mime,  Node: Charset Translation,  Next: Conversion,  Prev: Advanced MML Example,  Up: Composing

Charset Translation
===================

   During translation from MML to MIME, for each MIME part which has
been composed inside Emacs, an appropriate charset has to be chosen.

   If you are running a non-MULE Emacs, this process is simple: If the
part contains any non-ASCII (8-bit) characters, the MIME charset given
by `mail-parse-charset' (a symbol) is used.  (Never set this variable
directly, though.  If you want to change the default charset, please
consult the documentation of the package which you use to process MIME
messages.  *Note Various Message Variables: (message)Various Message
Variables, for example.)  If there are only ASCII characters, the MIME
charset US-ASCII is used, of course.

   Things are slightly more complicated when running Emacs with MULE
support.  In this case, a list of the MULE charsets used in the part is
obtained, and the MULE charsets are translated to MIME charsets by
consulting the variable `mm-mime-mule-charset-alist'.  If this results
in a single MIME charset, this is used to encode the part.  But if the
resulting list of MIME charsets contains more than one element, two
things can happen: If it is possible to encode the part via UTF-8, this
charset is used.  (For this, Emacs must support the `utf-8' coding
system, and the part must consist entirely of characters which have
Unicode counterparts.)  If UTF-8 is not available for some reason, the
part is split into several ones, so that each one can be encoded with a
single MIME charset.  The part can only be split at line boundaries,
though--if more than one MIME charset is required to encode a single
line, it is not possible to encode the part.


File: emacs-mime,  Node: Conversion,  Prev: Charset Translation,  Up: Composing

Conversion
==========

   A (multipart) MIME message can be converted to MML with the
`mime-to-mml' function.  It works on the message in the current buffer,
and substitutes MML markup for MIME boundaries.  Non-textual parts do
not have their contents in the buffer, but instead have the contents in
separate buffers that are referred to from the MML tags.

   An MML message can be converted back to MIME by the `mml-to-mime'
function.

   These functions are in certain senses "lossy"--you will not get back
an identical message if you run MIME-TO-MML and then MML-TO-MIME.  Not
only will trivial things like the order of the headers differ, but the
contents of the headers may also be different.  For instance, the
original message may use base64 encoding on text, while MML-TO-MIME may
decide to use quoted-printable encoding, and so on.

   In essence, however, these two functions should be the inverse of
each other.  The resulting contents of the message should remain
equivalent, if not identical.


File: emacs-mime,  Node: Standards,  Next: Index,  Prev: Composing,  Up: Top

Standards
*********

   The Emacs MIME library implements handling of various elements
according to a (somewhat) large number of RFCs, drafts and standards
documents.  This chapter lists the relevant ones.  They can all be
fetched from `http://quimby.gnus.org/notes/'.

"RFC822"
"STD11"
     Standard for the Format of ARPA Internet Text Messages.

"RFC1036"
     Standard for Interchange of USENET Messages

"RFC2045"
     Format of Internet Message Bodies

"RFC2046"
     Media Types

"RFC2047"
     Message Header Extensions for Non-ASCII Text

"RFC2048"
     Registration Procedures

"RFC2049"
     Conformance Criteria and Examples

"RFC2231"
     MIME Parameter Value and Encoded Word Extensions: Character Sets,
     Languages, and Continuations

"RFC1843"
     HZ - A Data Format for Exchanging Files of Arbitrarily Mixed
     Chinese and ASCII characters

"draft-ietf-drums-msg-fmt-05.txt"
     Draft for the successor of RFC822

"RFC2112"
     The MIME Multipart/Related Content-type

"RFC1892"
     The Multipart/Report Content Type for the Reporting of Mail System
     Administrative Messages

"RFC2183"
     Communicating Presentation Information in Internet Messages: The
     Content-Disposition Header Field


File: emacs-mime,  Node: Index,  Prev: Standards,  Up: Top

Index
*****

* Menu:

* Apple:                                 binhex.
* base64:                                base64.
* base64-decode-region:                  base64.
* base64-decode-string:                  base64.
* base64-encode-region:                  base64.
* base64-encode-string:                  base64.
* binhex:                                binhex.
* binhex-decode-region:                  binhex.
* charsets:                              Charset Translation.
* Chinese:                               rfc1843.
* Composing:                             Composing.
* HZ:                                    rfc1843.
* ietf-drums-get-comment:                ietf-drums.
* ietf-drums-narrow-to-header:           ietf-drums.
* ietf-drums-parse-address:              ietf-drums.
* ietf-drums-parse-addresses:            ietf-drums.
* ietf-drums-parse-date:                 ietf-drums.
* ietf-drums-remove-comments:            ietf-drums.
* ietf-drums-remove-whitespace:          ietf-drums.
* interface functions:                   Interface Functions.
* Macintosh:                             binhex.
* mail-content-type-get:                 Interface Functions.
* mail-decode-encoded-word-region:       Interface Functions.
* mail-decode-encoded-word-string:       Interface Functions.
* mail-encode-encoded-word-buffer:       Interface Functions.
* mail-encode-encoded-word-region:       Interface Functions.
* mail-encode-encoded-word-string:       Interface Functions.
* mail-header-encode-parameter:          Interface Functions.
* mail-header-get-comment:               Interface Functions.
* mail-header-narrow-to-field:           Interface Functions.
* mail-header-parse-address:             Interface Functions.
* mail-header-parse-addresses:           Interface Functions.
* mail-header-parse-content-disposition: Interface Functions.
* mail-header-parse-content-type:        Interface Functions.
* mail-header-parse-date:                Interface Functions.
* mail-header-remove-comments:           Interface Functions.
* mail-header-remove-whitespace:         Interface Functions.
* mail-narrow-to-head:                   Interface Functions.
* mail-parse:                            Interface Functions.
* mail-parse-charset:                    Charset Translation.
* mailcap-mime-data:                     mailcap.
* mailcap-parse-mailcaps:                mailcap.
* MIME Composing:                        Composing.
* MIME Meta Language:                    Composing.
* mime-to-mml:                           Conversion.
* mm-automatic-display-p:                Display.
* mm-destroy-part:                       Display.
* mm-display-part:                       Display.
* mm-handle-buffer:                      Handles.
* mm-handle-disposition:                 Handles.
* mm-handle-encoding:                    Handles.
* mm-handle-set-undisplayer:             Handles.
* mm-handle-type:                        Handles.
* mm-handle-undisplayer:                 Handles.
* mm-inlinable-p:                        Display.
* mm-interactively-view-part:            Display.
* mm-mime-mule-charset-alist:            Charset Translation.
* mm-pipe-part:                          Display.
* mm-remove-part:                        Display.
* mm-save-part:                          Display.
* MML:                                   Composing.
* mml-generate-mime:                     Composing.
* mml-to-mime:                           Conversion.
* MULE:                                  Charset Translation.
* quoted-printable-decode-region:        qp.
* quoted-printable-decode-string:        qp.
* quoted-printable-encode-region:        qp.
* quoted-printable-encode-string:        qp.
* rfc1843:                               rfc1843.
* rfc2045-encode-string:                 rfc2045.
* rfc2047-charset-encoding-alist:        rfc2047.
* rfc2047-decode-region:                 rfc2047.
* rfc2047-decode-string:                 rfc2047.
* rfc2047-default-charset:               rfc2047.
* rfc2047-encode-message-header:         rfc2047.
* rfc2047-encode-region:                 rfc2047.
* rfc2047-encode-string:                 rfc2047.
* rfc2047-encoded-word-regexp:           rfc2047.
* rfc2047-encoding-function-alist:       rfc2047.
* rfc2047-header-encoding-list:          rfc2047.
* rfc2047-narrow-to-field:               rfc2047.
* rfc2047-q-encoding-alist:              rfc2047.
* rfc2231-encode-string:                 rfc2231.
* rfc2231-get-value:                     rfc2231.
* rfc2231-parse-string:                  rfc2231.
* Unicode:                               Charset Translation.
* UTF-8:                                 Charset Translation.
* uudecode:                              uudecode.
* uudecode-decode-region:                uudecode.
* uuencode:                              uudecode.



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Node: Interface Functions2436
Node: Basic Functions7747
Node: rfc20458769
Node: rfc22319279
Node: ietf-drums10562
Node: rfc204711641
Node: time-date13812
Node: qp15395
Node: base6416356
Node: binhex17303
Node: uudecode17692
Node: rfc184318046
Node: mailcap18650
Node: Decoding and Viewing19440
Node: Dissection20077
Node: Handles20445
Node: Display21359
Node: Customization22066
Node: New Viewers25010
Node: Composing26121
Node: Simple MML Example26945
Node: MML Definition27623
Node: Advanced MML Example30437
Node: Charset Translation33274
Node: Conversion35048
Node: Standards36139
Node: Index37445

End Tag Table
