3 @setfilename emacs-mime
4 @settitle Emacs MIME Manual
10 * Emacs MIME: (emacs-mime). The MIME de/composition library.
15 @setchapternewpage odd
19 This file documents the Emacs MIME interface functionality.
21 Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
22 Free Software Foundation, Inc.
24 Permission is granted to copy, distribute and/or modify this document
25 under the terms of the GNU Free Documentation License, Version 1.1 or
26 any later version published by the Free Software Foundation; with no
27 Invariant Sections, with the Front-Cover texts being ``A GNU
28 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
29 license is included in the section entitled ``GNU Free Documentation
30 License'' in the Emacs manual.
32 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
33 this GNU Manual, like GNU software. Copies published by the Free
34 Software Foundation raise funds for GNU development.''
36 This document is part of a collection distributed under the GNU Free
37 Documentation License. If you want to distribute this document
38 separately from the collection, you can do so by adding a copy of the
39 license to the document, as described in section 6 of the license.
45 @title Emacs MIME Manual
47 @author by Lars Magne Ingebrigtsen
50 @vskip 0pt plus 1filll
51 Copyright @copyright{} 1998, 1999, 2000, 2001, 2002, 2003 Free Software
54 Permission is granted to copy, distribute and/or modify this document
55 under the terms of the GNU Free Documentation License, Version 1.1 or
56 any later version published by the Free Software Foundation; with the
57 Invariant Sections being none, with the Front-Cover texts being ``A GNU
58 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
59 license is included in the section entitled ``GNU Free Documentation
60 License'' in the Emacs manual.
62 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
63 this GNU Manual, like GNU software. Copies published by the Free
64 Software Foundation raise funds for GNU development.''
66 This document is part of a collection distributed under the GNU Free
67 Documentation License. If you want to distribute this document
68 separately from the collection, you can do so by adding a copy of the
69 license to the document, as described in section 6 of the license.
78 This manual documents the libraries used to compose and display
81 This manual is directed at users who want to modify the behaviour of
82 the @sc{mime} encoding/decoding process or want a more detailed
83 picture of how the Emacs @sc{mime} library works, and people who want
84 to write functions and commands that manipulate @sc{mime} elements.
86 @sc{mime} is short for @dfn{Multipurpose Internet Mail Extensions}.
87 This standard is documented in a number of RFCs; mainly RFC2045 (Format
88 of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message
89 Header Extensions for Non-ASCII Text), RFC2048 (Registration
90 Procedures), RFC2049 (Conformance Criteria and Examples). It is highly
91 recommended that anyone who intends writing @sc{mime}-compliant software
92 read at least RFC2045 and RFC2047.
95 * Decoding and Viewing:: A framework for decoding and viewing.
96 * Composing:: MML; a language for describing @sc{mime} parts.
97 * Interface Functions:: An abstraction over the basic functions.
98 * Basic Functions:: Utility and basic parsing functions.
99 * Standards:: A summary of RFCs and working documents used.
100 * Index:: Function and variable index.
104 @node Decoding and Viewing
105 @chapter Decoding and Viewing
107 This chapter deals with decoding and viewing @sc{mime} messages on a
110 The main idea is to first analyze a @sc{mime} article, and then allow
111 other programs to do things based on the list of @dfn{handles} that are
112 returned as a result of this analysis.
115 * Dissection:: Analyzing a @sc{mime} message.
116 * Non-MIME:: Analyzing a non-@sc{mime} message.
117 * Handles:: Handle manipulations.
118 * Display:: Displaying handles.
119 * Display Customization:: Variables that affect display.
120 * Files and Directories:: Saving and naming attachments.
121 * New Viewers:: How to write your own viewers.
128 The @code{mm-dissect-buffer} is the function responsible for dissecting
129 a @sc{mime} article. If given a multipart message, it will recursively
130 descend the message, following the structure, and return a tree of
131 @sc{mime} handles that describes the structure of the message.
135 @vindex mm-uu-configure-list
137 Gnus also understands some non-@sc{mime} attachments, such as
138 postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp.
139 Each of these features can be disabled by add an item into
140 @code{mm-uu-configure-list}. For example,
144 (add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
170 Non-@sc{mime} forwarded message.
178 PGP signed clear text.
181 @findex pgp-encrypted
182 PGP encrypted clear text.
189 @findex emacs-sources
190 Emacs source code. This item works only in the groups matching
191 @code{mm-uu-emacs-sources-regexp}.
198 A @sc{mime} handle is a list that fully describes a @sc{mime}
201 The following macros can be used to access elements in a handle:
204 @item mm-handle-buffer
205 @findex mm-handle-buffer
206 Return the buffer that holds the contents of the undecoded @sc{mime}
210 @findex mm-handle-type
211 Return the parsed @code{Content-Type} of the part.
213 @item mm-handle-encoding
214 @findex mm-handle-encoding
215 Return the @code{Content-Transfer-Encoding} of the part.
217 @item mm-handle-undisplayer
218 @findex mm-handle-undisplayer
219 Return the object that can be used to remove the displayed part (if it
222 @item mm-handle-set-undisplayer
223 @findex mm-handle-set-undisplayer
224 Set the undisplayer object.
226 @item mm-handle-disposition
227 @findex mm-handle-disposition
228 Return the parsed @code{Content-Disposition} of the part.
230 @item mm-handle-disposition
231 @findex mm-handle-disposition
232 Return the description of the part.
234 @item mm-get-content-id
235 Returns the handle(s) referred to by @code{Content-ID}.
243 Functions for displaying, removing and saving.
246 @item mm-display-part
247 @findex mm-display-part
251 @findex mm-remove-part
252 Remove the part (if it has been displayed).
255 @findex mm-inlinable-p
256 Say whether a @sc{mime} type can be displayed inline.
258 @item mm-automatic-display-p
259 @findex mm-automatic-display-p
260 Say whether a @sc{mime} type should be displayed automatically.
262 @item mm-destroy-part
263 @findex mm-destroy-part
264 Free all resources occupied by a part.
268 Offer to save the part in a file.
272 Offer to pipe the part to some process.
274 @item mm-interactively-view-part
275 @findex mm-interactively-view-part
276 Prompt for a mailcap method to use to view the part.
281 @node Display Customization
282 @section Display Customization
286 @item mm-inline-media-tests
287 @vindex mm-inline-media-tests
288 This is an alist where the key is a @sc{mime} type, the second element
289 is a function to display the part @dfn{inline} (i.e., inside Emacs), and
290 the third element is a form to be @code{eval}ed to say whether the part
291 can be displayed inline.
293 This variable specifies whether a part @emph{can} be displayed inline,
294 and, if so, how to do it. It does not say whether parts are
295 @emph{actually} displayed inline.
297 @item mm-inlined-types
298 @vindex mm-inlined-types
299 This, on the other hand, says what types are to be displayed inline, if
300 they satisfy the conditions set by the variable above. It's a list of
301 @sc{mime} media types.
303 @item mm-automatic-display
304 @vindex mm-automatic-display
305 This is a list of types that are to be displayed ``automatically'', but
306 only if the above variable allows it. That is, only inlinable parts can
307 be displayed automatically.
309 @item mm-automatic-external-display
310 @vindex mm-automatic-external-display
311 This is a list of types that will be displayed automatically in an
314 @item mm-keep-viewer-alive-types
315 @vindex mm-keep-viewer-alive-types
316 This is a list of media types for which the external viewer will not
317 be killed when selecting a different article.
319 @item mm-attachment-override-types
320 @vindex mm-attachment-override-types
321 Some @sc{mime} agents create parts that have a content-disposition of
322 @samp{attachment}. This variable allows overriding that disposition and
323 displaying the part inline. (Note that the disposition is only
324 overridden if we are able to, and want to, display the part inline.)
326 @item mm-discouraged-alternatives
327 @vindex mm-discouraged-alternatives
328 List of @sc{mime} types that are discouraged when viewing
329 @samp{multipart/alternative}. Viewing agents are supposed to view the
330 last possible part of a message, as that is supposed to be the richest.
331 However, users may prefer other types instead, and this list says what
332 types are most unwanted. If, for instance, @samp{text/html} parts are
333 very unwanted, and @samp{text/richtext} parts are somewhat unwanted,
334 you could say something like:
337 (setq mm-discouraged-alternatives
338 '("text/html" "text/richtext")
340 (remove "text/html" mm-automatic-display))
343 @item mm-inline-large-images
344 @vindex mm-inline-large-images
345 When displaying inline images that are larger than the window, XEmacs
346 does not enable scrolling, which means that you cannot see the whole
347 image. To prevent this, the library tries to determine the image size
348 before displaying it inline, and if it doesn't fit the window, the
349 library will display it externally (e.g. with @samp{ImageMagick} or
350 @samp{xv}). Setting this variable to @code{t} disables this check and
351 makes the library display all inline images as inline, regardless of
354 @item mm-inline-override-types
355 @vindex mm-inline-override-types
356 @code{mm-inlined-types} may include regular expressions, for example to
357 specify that all @samp{text/.*} parts be displayed inline. If a user
358 prefers to have a type that matches such a regular expression be treated
359 as an attachment, that can be accomplished by setting this variable to a
360 list containing that type. For example assuming @code{mm-inlined-types}
361 includes @samp{text/.*}, then including @samp{text/html} in this
362 variable will cause @samp{text/html} parts to be treated as attachments.
364 @item mm-text-html-renderer
365 @vindex mm-text-html-renderer
366 This selects the function used to render @sc{html}. The predefined
367 renderers are selected by the symbols @code{w3},
368 @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
369 information about emacs-w3m}, @code{links}, @code{lynx},
370 @code{w3m-standalone} or @code{html2text}. If @code{nil} use an
371 external viewer. You can also specify a function, which will be
372 called with a @sc{mime} handle as the argument.
374 @item mm-inline-text-html-with-images
375 @vindex mm-inline-text-html-with-images
376 Some @sc{html} mails might have the trick of spammers using
377 @samp{<img>} tags. It is likely to be intended to verify whether you
378 have read the mail. You can prevent your personal informations from
379 leaking by setting this option to @code{nil} (which is the default).
380 It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
381 command @kbd{t} on the image anchor to show an image even if it is
382 @code{nil}.@footnote{The command @kbd{T} will load all images. If you
383 have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
386 @item mm-w3m-safe-url-regexp
387 @vindex mm-w3m-safe-url-regexp
388 A regular expression that matches safe URL names, i.e. URLs that are
389 unlikely to leak personal information when rendering @sc{html} email
390 (the default value is @samp{\\`cid:}). If @code{nil} consider all
393 @item mm-inline-text-html-with-w3m-keymap
394 @vindex mm-inline-text-html-with-w3m-keymap
395 You can use emacs-w3m command keys in the inlined text/html part by
396 setting this option to non-@code{nil}. The default value is @code{t}.
398 @item mm-external-terminal-program
399 @vindex mm-external-terminal-program
400 The program used to start an external terminal.
404 @node Files and Directories
405 @section Files and Directories
409 @item mm-default-directory
410 @vindex mm-default-directory
411 The default directory for saving attachments. If @code{nil} use
412 @code{default-directory}.
414 @item mm-tmp-directory
415 @vindex mm-tmp-directory
416 Directory for storing temporary files.
418 @item mm-file-name-rewrite-functions
419 @vindex mm-file-name-rewrite-functions
420 A list of functions used for rewriting file names of @sc{mime}
421 parts. Each function is applied successively to the file name.
422 Ready-made functions include
425 @item mm-file-name-delete-whitespace
426 @findex mm-file-name-delete-whitespace
427 Remove all whitespace.
429 @item mm-file-name-trim-whitespace
430 @findex mm-file-name-trim-whitespace
431 Remove leading and trailing whitespace.
433 @item mm-file-name-collapse-whitespace
434 @findex mm-file-name-collapse-whitespace
435 Collapse multiple whitespace characters.
437 @item mm-file-name-replace-whitespace
438 @findex mm-file-name-replace-whitespace
439 @vindex mm-file-name-replace-whitespace
440 Replace whitespace with underscores. Set the variable
441 @code{mm-file-name-replace-whitespace} to any other string if you do
442 not like underscores.
446 The standard Emacs functions @code{capitalize}, @code{downcase},
447 @code{upcase} and @code{upcase-initials} might also prove useful.
449 @item mm-path-name-rewrite-functions
450 @vindex mm-path-name-rewrite-functions
451 List of functions used for rewriting the full file names of @sc{mime}
452 parts. This is used when viewing parts externally, and is meant for
453 transforming the absolute name so that non-compliant programs can find
454 the file where it's saved.
461 Here's an example viewer for displaying @code{text/enriched} inline:
464 (defun mm-display-enriched-inline (handle)
467 (mm-insert-part handle)
468 (save-window-excursion
469 (enriched-decode (point-min) (point-max))
470 (setq text (buffer-string))))
471 (mm-insert-inline handle text)))
474 We see that the function takes a @sc{mime} handle as its parameter. It
475 then goes to a temporary buffer, inserts the text of the part, does some
476 work on the text, stores the result, goes back to the buffer it was
477 called from and inserts the result.
479 The two important helper functions here are @code{mm-insert-part} and
480 @code{mm-insert-inline}. The first function inserts the text of the
481 handle in the current buffer. It handles charset and/or content
482 transfer decoding. The second function just inserts whatever text you
483 tell it to insert, but it also sets things up so that the text can be
484 ``undisplayed'' in a convenient manner.
490 @cindex MIME Composing
492 @cindex MIME Meta Language
494 Creating a @sc{mime} message is boring and non-trivial. Therefore, a
495 library called @code{mml} has been defined that parses a language called
496 MML (@sc{mime} Meta Language) and generates @sc{mime} messages.
498 @findex mml-generate-mime
499 The main interface function is @code{mml-generate-mime}. It will
500 examine the contents of the current (narrowed-to) buffer and return a
501 string containing the @sc{mime} message.
504 * Simple MML Example:: An example MML document.
505 * MML Definition:: All valid MML elements.
506 * Advanced MML Example:: Another example MML document.
507 * Encoding Customization:: Variables that affect encoding.
508 * Charset Translation:: How charsets are mapped from @sc{mule} to @sc{mime}.
509 * Conversion:: Going from @sc{mime} to MML and vice versa.
510 * Flowed text:: Soft and hard newlines.
514 @node Simple MML Example
515 @section Simple MML Example
517 Here's a simple @samp{multipart/alternative}:
520 <#multipart type=alternative>
521 This is a plain text part.
522 <#part type=text/enriched>
523 <center>This is a centered enriched part</center>
527 After running this through @code{mml-generate-mime}, we get this:
530 Content-Type: multipart/alternative; boundary="=-=-="
536 This is a plain text part.
539 Content-Type: text/enriched
542 <center>This is a centered enriched part</center>
549 @section MML Definition
551 The MML language is very simple. It looks a bit like an SGML
552 application, but it's not.
554 The main concept of MML is the @dfn{part}. Each part can be of a
555 different type or use a different charset. The way to delineate a part
556 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
557 with the @samp{<#multipart ...>} tag. Parts are ended by the
558 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
559 @samp{<#part ...>} tags are also closed by the next open tag.
561 There's also the @samp{<#external ...>} tag. These introduce
562 @samp{external/message-body} parts.
564 Each tag can contain zero or more parameters on the form
565 @samp{parameter=value}. The values may be enclosed in quotation marks,
566 but that's not necessary unless the value contains white space. So
567 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
569 The following parameters have meaning in MML; parameters that have no
570 meaning are ignored. The MML parameter names are the same as the
571 @sc{mime} parameter names; the things in the parentheses say which
572 header it will be used in.
576 The @sc{mime} type of the part (@code{Content-Type}).
579 Use the contents of the file in the body of the part
580 (@code{Content-Disposition}).
583 The contents of the body of the part are to be encoded in the character
584 set speficied (@code{Content-Type}). @xref{Charset Translation}.
587 Might be used to suggest a file name if the part is to be saved
588 to a file (@code{Content-Type}).
591 Valid values are @samp{inline} and @samp{attachment}
592 (@code{Content-Disposition}).
595 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
596 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
600 A description of the part (@code{Content-Description}).
603 RFC822 date when the part was created (@code{Content-Disposition}).
605 @item modification-date
606 RFC822 date when the part was modified (@code{Content-Disposition}).
609 RFC822 date when the part was read (@code{Content-Disposition}).
612 Who to encrypt/sign the part to. This field is used to override any
613 auto-detection based on the To/CC headers.
616 The size (in octets) of the part (@code{Content-Disposition}).
619 What technology to sign this MML part with (@code{smime}, @code{pgp}
623 What technology to encrypt this MML part with (@code{smime},
624 @code{pgp} or @code{pgpmime})
628 Parameters for @samp{application/octet-stream}:
632 Type of the part; informal---meant for human readers
633 (@code{Content-Type}).
636 Parameters for @samp{message/external-body}:
640 A word indicating the supported access mechanism by which the file may
641 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
642 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
645 The RFC822 date after which the file may no longer be fetched.
646 (@code{Content-Type}.)
649 The size (in octets) of the file. (@code{Content-Type}.)
652 Valid values are @samp{read} and @samp{read-write}
653 (@code{Content-Type}).
657 Parameters for @samp{sign=smime}:
662 File containing key and certificate for signer.
666 Parameters for @samp{encrypt=smime}:
671 File containing certificate for recipient.
676 @node Advanced MML Example
677 @section Advanced MML Example
679 Here's a complex multipart message. It's a @samp{multipart/mixed} that
680 contains many parts, one of which is a @samp{multipart/alternative}.
683 <#multipart type=mixed>
684 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
685 <#multipart type=alternative>
686 This is a plain text part.
687 <#part type=text/enriched name=enriched.txt>
688 <center>This is a centered enriched part</center>
690 This is a new plain text part.
691 <#part disposition=attachment>
692 This plain text part is an attachment.
696 And this is the resulting @sc{mime} message:
699 Content-Type: multipart/mixed; boundary="=-=-="
707 Content-Type: image/jpeg;
709 Content-Disposition: inline;
711 Content-Transfer-Encoding: base64
713 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
714 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
715 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
716 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
717 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
718 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
719 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
720 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
721 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
722 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
723 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
724 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
725 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
726 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
727 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
728 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
729 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
732 Content-Type: multipart/alternative; boundary="==-=-="
738 This is a plain text part.
741 Content-Type: text/enriched;
745 <center>This is a centered enriched part</center>
751 This is a new plain text part.
754 Content-Disposition: attachment
757 This plain text part is an attachment.
762 @node Encoding Customization
763 @section Encoding Customization
767 @item mm-body-charset-encoding-alist
768 @vindex mm-body-charset-encoding-alist
769 Mapping from @sc{mime} charset to encoding to use. This variable is
770 usually used except, e.g., when other requirements force a specific
771 encoding (digitally signed messages require 7bit encodings). The
772 default is @code{((iso-2022-jp . 7bit) (iso-2022-jp-2 . 7bit))}. As
773 an example, if you do not want to have ISO-8859-1 characters
774 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
775 this variable. You can override this setting on a per-message basis
776 by using the @code{encoding} MML tag (@pxref{MML Definition}).
778 @item mm-coding-system-priorities
779 @vindex mm-coding-system-priorities
780 Prioritize coding systems to use for outgoing messages. The default
781 is @code{nil}, which means to use the defaults in Emacs. It is a list of
782 coding system symbols (aliases of coding systems does not work, use
783 @kbd{M-x describe-coding-system} to make sure you are not specifying
784 an alias in this variable). For example, if you have configured Emacs
785 to use prefer UTF-8, but wish that outgoing messages should be sent in
786 ISO-8859-1 if possible, you can set this variable to
787 @code{(iso-latin-1)}. You can override this setting on a per-message
788 basis by using the @code{charset} MML tag (@pxref{MML Definition}).
790 @item mm-content-transfer-encoding-defaults
791 @vindex mm-content-transfer-encoding-defaults
792 Mapping from @sc{mime} types to encoding to use. This variable is usually
793 used except, e.g., when other requirements force a safer encoding
794 (digitally signed messages require 7bit encoding). Besides the normal
795 @sc{mime} encodings, @code{qp-or-base64} may be used to indicate that for
796 each case the most efficient of quoted-printable and base64 should be
797 used. You can override this setting on a per-message basis by using
798 the @code{encoding} MML tag (@pxref{MML Definition}).
800 @item mm-use-ultra-safe-encoding
801 @vindex mm-use-ultra-safe-encoding
802 When this is non-@code{nil}, it means that textual parts are encoded as
803 quoted-printable if they contain lines longer than 76 characters or
804 starting with "From " in the body. Non-7bit encodings (8bit, binary)
805 are generally disallowed. This reduce the probability that a non-8bit
806 clean MTA or MDA changes the message. This should never be set
807 directly, but bound by other functions when necessary (e.g., when
808 encoding messages that are to be digitally signed).
812 @node Charset Translation
813 @section Charset Translation
816 During translation from MML to @sc{mime}, for each @sc{mime} part which
817 has been composed inside Emacs, an appropriate charset has to be chosen.
819 @vindex mail-parse-charset
820 If you are running a non-@sc{mule} Emacs, this process is simple: If the
821 part contains any non-ASCII (8-bit) characters, the @sc{mime} charset
822 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
823 variable directly, though. If you want to change the default charset,
824 please consult the documentation of the package which you use to process
826 @xref{Various Message Variables, , Various Message Variables, message,
827 Message Manual}, for example.)
828 If there are only ASCII characters, the @sc{mime} charset US-ASCII is
834 @vindex mm-mime-mule-charset-alist
835 Things are slightly more complicated when running Emacs with @sc{mule}
836 support. In this case, a list of the @sc{mule} charsets used in the
837 part is obtained, and the @sc{mule} charsets are translated to @sc{mime}
838 charsets by consulting the variable @code{mm-mime-mule-charset-alist}.
839 If this results in a single @sc{mime} charset, this is used to encode
840 the part. But if the resulting list of @sc{mime} charsets contains more
841 than one element, two things can happen: If it is possible to encode the
842 part via UTF-8, this charset is used. (For this, Emacs must support
843 the @code{utf-8} coding system, and the part must consist entirely of
844 characters which have Unicode counterparts.) If UTF-8 is not available
845 for some reason, the part is split into several ones, so that each one
846 can be encoded with a single @sc{mime} charset. The part can only be
847 split at line boundaries, though---if more than one @sc{mime} charset is
848 required to encode a single line, it is not possible to encode the part.
850 When running Emacs with @sc{mule} support, the preferences for which
851 coding system to use is inherited from Emacs itself. This means that
852 if Emacs is set up to prefer UTF-8, it will be used when encoding
853 messages. You can modify this by altering the
854 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
857 The charset to be used can be overriden by setting the @code{charset}
858 MML tag (@pxref{MML Definition}) when composing the message.
860 The encoding of characters (quoted-printable, 8bit etc) is orthogonal
861 to the discussion here, and is controlled by the variables
862 @code{mm-body-charset-encoding-alist} and
863 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
870 A (multipart) @sc{mime} message can be converted to MML with the
871 @code{mime-to-mml} function. It works on the message in the current
872 buffer, and substitutes MML markup for @sc{mime} boundaries.
873 Non-textual parts do not have their contents in the buffer, but instead
874 have the contents in separate buffers that are referred to from the MML
878 An MML message can be converted back to @sc{mime} by the
879 @code{mml-to-mime} function.
881 These functions are in certain senses ``lossy''---you will not get back
882 an identical message if you run @sc{mime-to-mml} and then
883 @sc{mml-to-mime}. Not only will trivial things like the order of the
884 headers differ, but the contents of the headers may also be different.
885 For instance, the original message may use base64 encoding on text,
886 while @sc{mml-to-mime} may decide to use quoted-printable encoding, and
889 In essence, however, these two functions should be the inverse of each
890 other. The resulting contents of the message should remain equivalent,
896 @cindex format=flowed
898 The Emacs @sc{mime} library will respect the @code{use-hard-newlines}
899 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
900 emacs, Emacs Manual}) when encoding a message, and the
901 ``format=flowed'' Content-Type parameter when decoding a message.
903 On encoding text, lines terminated by soft newline characters are
904 filled together and wrapped after the column decided by
905 @code{fill-flowed-encode-column}. This variable controls how the text
906 will look in a client that does not support flowed text, the default
907 is to wrap after 66 characters. If hard newline characters are not
908 present in the buffer, no flow encoding occurs.
910 On decoding flowed text, lines with soft newline characters are filled
911 together and wrapped after the column decided by
912 @code{fill-flowed-display-column}. The default is to wrap after
918 @node Interface Functions
919 @chapter Interface Functions
920 @cindex interface functions
923 The @code{mail-parse} library is an abstraction over the actual
924 low-level libraries that are described in the next chapter.
926 Standards change, and so programs have to change to fit in the new
927 mold. For instance, RFC2045 describes a syntax for the
928 @code{Content-Type} header that only allows ASCII characters in the
929 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
930 for continuation headers and non-ASCII characters.
932 The traditional way to deal with this is just to update the library
933 functions to parse the new syntax. However, this is sometimes the wrong
934 thing to do. In some instances it may be vital to be able to understand
935 both the old syntax as well as the new syntax, and if there is only one
936 library, one must choose between the old version of the library and the
937 new version of the library.
939 The Emacs @sc{mime} library takes a different tack. It defines a
940 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
941 and so on) that parses strictly according to the corresponding
942 standard. However, normal programs would not use the functions
943 provided by these libraries directly, but instead use the functions
944 provided by the @code{mail-parse} library. The functions in this
945 library are just aliases to the corresponding functions in the latest
946 low-level libraries. Using this scheme, programs get a consistent
947 interface they can use, and library developers are free to create
948 write code that handles new standards.
950 The following functions are defined by this library:
953 @item mail-header-parse-content-type
954 @findex mail-header-parse-content-type
955 Parse a @code{Content-Type} header and return a list on the following
960 (attribute1 . value1)
961 (attribute2 . value2)
968 (mail-header-parse-content-type
969 "image/gif; name=\"b980912.gif\"")
970 @result{} ("image/gif" (name . "b980912.gif"))
973 @item mail-header-parse-content-disposition
974 @findex mail-header-parse-content-disposition
975 Parse a @code{Content-Disposition} header and return a list on the same
976 format as the function above.
978 @item mail-content-type-get
979 @findex mail-content-type-get
980 Takes two parameters---a list on the format above, and an attribute.
981 Returns the value of the attribute.
984 (mail-content-type-get
985 '("image/gif" (name . "b980912.gif")) 'name)
986 @result{} "b980912.gif"
989 @item mail-header-encode-parameter
990 @findex mail-header-encode-parameter
991 Takes a parameter string and returns an encoded version of the string.
992 This is used for parameters in headers like @code{Content-Type} and
993 @code{Content-Disposition}.
995 @item mail-header-remove-comments
996 @findex mail-header-remove-comments
997 Return a comment-free version of a header.
1000 (mail-header-remove-comments
1001 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1002 @result{} "Gnus/5.070027 "
1005 @item mail-header-remove-whitespace
1006 @findex mail-header-remove-whitespace
1007 Remove linear white space from a header. Space inside quoted strings
1008 and comments is preserved.
1011 (mail-header-remove-whitespace
1012 "image/gif; name=\"Name with spaces\"")
1013 @result{} "image/gif;name=\"Name with spaces\""
1016 @item mail-header-get-comment
1017 @findex mail-header-get-comment
1018 Return the last comment in a header.
1021 (mail-header-get-comment
1022 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1023 @result{} "Finnish Landrace"
1026 @item mail-header-parse-address
1027 @findex mail-header-parse-address
1028 Parse an address and return a list containing the mailbox and the
1032 (mail-header-parse-address
1033 "Hrvoje Niksic <hniksic@@srce.hr>")
1034 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1037 @item mail-header-parse-addresses
1038 @findex mail-header-parse-addresses
1039 Parse a string with list of addresses and return a list of elements like
1040 the one described above.
1043 (mail-header-parse-addresses
1044 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1045 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1046 ("sb@@metis.no" . "Steinar Bang"))
1049 @item mail-header-parse-date
1050 @findex mail-header-parse-date
1051 Parse a date string and return an Emacs time structure.
1053 @item mail-narrow-to-head
1054 @findex mail-narrow-to-head
1055 Narrow the buffer to the header section of the buffer. Point is placed
1056 at the beginning of the narrowed buffer.
1058 @item mail-header-narrow-to-field
1059 @findex mail-header-narrow-to-field
1060 Narrow the buffer to the header under point. Understands continuation
1063 @item mail-header-fold-field
1064 @findex mail-header-fold-field
1065 Fold the header under point.
1067 @item mail-header-unfold-field
1068 @findex mail-header-unfold-field
1069 Unfold the header under point.
1071 @item mail-header-field-value
1072 @findex mail-header-field-value
1073 Return the value of the field under point.
1075 @item mail-encode-encoded-word-region
1076 @findex mail-encode-encoded-word-region
1077 Encode the non-ASCII words in the region. For instance,
1078 @samp{Naïve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1080 @item mail-encode-encoded-word-buffer
1081 @findex mail-encode-encoded-word-buffer
1082 Encode the non-ASCII words in the current buffer. This function is
1083 meant to be called narrowed to the headers of a message.
1085 @item mail-encode-encoded-word-string
1086 @findex mail-encode-encoded-word-string
1087 Encode the words that need encoding in a string, and return the result.
1090 (mail-encode-encoded-word-string
1091 "This is naïve, baby")
1092 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1095 @item mail-decode-encoded-word-region
1096 @findex mail-decode-encoded-word-region
1097 Decode the encoded words in the region.
1099 @item mail-decode-encoded-word-string
1100 @findex mail-decode-encoded-word-string
1101 Decode the encoded words in the string and return the result.
1104 (mail-decode-encoded-word-string
1105 "This is =?iso-8859-1?q?na=EFve,?= baby")
1106 @result{} "This is naïve, baby"
1111 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1112 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1113 in the subsequent sections.
1117 @node Basic Functions
1118 @chapter Basic Functions
1120 This chapter describes the basic, ground-level functions for parsing and
1121 handling. Covered here is parsing @code{From} lines, removing comments
1122 from header lines, decoding encoded words, parsing date headers and so
1123 on. High-level functionality is dealt with in the next chapter
1124 (@pxref{Decoding and Viewing}).
1127 * rfc2045:: Encoding @code{Content-Type} headers.
1128 * rfc2231:: Parsing @code{Content-Type} headers.
1129 * ietf-drums:: Handling mail headers defined by RFC822bis.
1130 * rfc2047:: En/decoding encoded words in headers.
1131 * time-date:: Functions for parsing dates and manipulating time.
1132 * qp:: Quoted-Printable en/decoding.
1133 * base64:: Base64 en/decoding.
1134 * binhex:: Binhex decoding.
1135 * uudecode:: Uuencode decoding.
1136 * yenc:: Yenc decoding.
1137 * rfc1843:: Decoding HZ-encoded text.
1138 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1145 RFC2045 is the ``main'' @sc{mime} document, and as such, one would
1146 imagine that there would be a lot to implement. But there isn't, since
1147 most of the implementation details are delegated to the subsequent
1150 So @file{rfc2045.el} has only a single function:
1153 @item rfc2045-encode-string
1154 @findex rfc2045-encode-string
1155 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1156 @var{value} will be quoted if there are non-safe characters in it.
1163 RFC2231 defines a syntax for the @code{Content-Type} and
1164 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1165 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1168 In short, these headers look something like this:
1171 Content-Type: application/x-stuff;
1172 title*0*=us-ascii'en'This%20is%20even%20more%20;
1173 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1177 They usually aren't this bad, though.
1179 The following functions are defined by this library:
1182 @item rfc2231-parse-string
1183 @findex rfc2231-parse-string
1184 Parse a @code{Content-Type} header and return a list describing its
1188 (rfc2231-parse-string
1189 "application/x-stuff;
1190 title*0*=us-ascii'en'This%20is%20even%20more%20;
1191 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1192 title*2=\"isn't it!\"")
1193 @result{} ("application/x-stuff"
1194 (title . "This is even more ***fun*** isn't it!"))
1197 @item rfc2231-get-value
1198 @findex rfc2231-get-value
1199 Takes one of the lists on the format above and returns
1200 the value of the specified attribute.
1202 @item rfc2231-encode-string
1203 @findex rfc2231-encode-string
1204 Encode a parameter in headers likes @code{Content-Type} and
1205 @code{Content-Disposition}.
1213 @dfn{drums} is an IETF working group that is working on the replacement
1216 The functions provided by this library include:
1219 @item ietf-drums-remove-comments
1220 @findex ietf-drums-remove-comments
1221 Remove the comments from the argument and return the results.
1223 @item ietf-drums-remove-whitespace
1224 @findex ietf-drums-remove-whitespace
1225 Remove linear white space from the string and return the results.
1226 Spaces inside quoted strings and comments are left untouched.
1228 @item ietf-drums-get-comment
1229 @findex ietf-drums-get-comment
1230 Return the last most comment from the string.
1232 @item ietf-drums-parse-address
1233 @findex ietf-drums-parse-address
1234 Parse an address string and return a list that contains the mailbox and
1235 the plain text name.
1237 @item ietf-drums-parse-addresses
1238 @findex ietf-drums-parse-addresses
1239 Parse a string that contains any number of comma-separated addresses and
1240 return a list that contains mailbox/plain text pairs.
1242 @item ietf-drums-parse-date
1243 @findex ietf-drums-parse-date
1244 Parse a date string and return an Emacs time structure.
1246 @item ietf-drums-narrow-to-header
1247 @findex ietf-drums-narrow-to-header
1248 Narrow the buffer to the header section of the current buffer.
1256 RFC2047 (Message Header Extensions for Non-ASCII Text) specifies how
1257 non-ASCII text in headers are to be encoded. This is actually rather
1258 complicated, so a number of variables are necessary to tweak what this
1261 The following variables are tweakable:
1264 @item rfc2047-default-charset
1265 @vindex rfc2047-default-charset
1266 Characters in this charset should not be decoded by this library.
1267 This defaults to @code{iso-8859-1}.
1269 @item rfc2047-header-encoding-alist
1270 @vindex rfc2047-header-encoding-alist
1271 This is an alist of header / encoding-type pairs. Its main purpose is
1272 to prevent encoding of certain headers.
1274 The keys can either be header regexps, or @code{t}.
1276 The values can be either @code{nil}, in which case the header(s) in
1277 question won't be encoded, or @code{mime}, which means that they will be
1280 @item rfc2047-charset-encoding-alist
1281 @vindex rfc2047-charset-encoding-alist
1282 RFC2047 specifies two forms of encoding---@code{Q} (a
1283 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1284 specifies which charset should use which encoding.
1286 @item rfc2047-encoding-function-alist
1287 @vindex rfc2047-encoding-function-alist
1288 This is an alist of encoding / function pairs. The encodings are
1289 @code{Q}, @code{B} and @code{nil}.
1291 @item rfc2047-q-encoding-alist
1292 @vindex rfc2047-q-encoding-alist
1293 The @code{Q} encoding isn't quite the same for all headers. Some
1294 headers allow a narrower range of characters, and that is what this
1295 variable is for. It's an alist of header regexps / allowable character
1298 @item rfc2047-encoded-word-regexp
1299 @vindex rfc2047-encoded-word-regexp
1300 When decoding words, this library looks for matches to this regexp.
1304 Those were the variables, and these are this functions:
1307 @item rfc2047-narrow-to-field
1308 @findex rfc2047-narrow-to-field
1309 Narrow the buffer to the header on the current line.
1311 @item rfc2047-encode-message-header
1312 @findex rfc2047-encode-message-header
1313 Should be called narrowed to the header of a message. Encodes according
1314 to @code{rfc2047-header-encoding-alist}.
1316 @item rfc2047-encode-region
1317 @findex rfc2047-encode-region
1318 Encodes all encodable words in the region specified.
1320 @item rfc2047-encode-string
1321 @findex rfc2047-encode-string
1322 Encode a string and return the results.
1324 @item rfc2047-decode-region
1325 @findex rfc2047-decode-region
1326 Decode the encoded words in the region.
1328 @item rfc2047-decode-string
1329 @findex rfc2047-decode-string
1330 Decode a string and return the results.
1338 While not really a part of the @sc{mime} library, it is convenient to
1339 document this library here. It deals with parsing @code{Date} headers
1340 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1343 These functions convert between five formats: A date string, an Emacs
1344 time structure, a decoded time list, a second number, and a day number.
1346 Here's a bunch of time/date/second/day examples:
1349 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1350 @result{} (54 21 12 12 9 1998 6 nil 7200)
1352 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1353 @result{} (13818 19266)
1355 (time-to-seconds '(13818 19266))
1356 @result{} 905595714.0
1358 (seconds-to-time 905595714.0)
1359 @result{} (13818 19266 0)
1361 (time-to-days '(13818 19266))
1364 (days-to-time 729644)
1365 @result{} (961933 65536)
1367 (time-since '(13818 19266))
1370 (time-less-p '(13818 19266) '(13818 19145))
1373 (subtract-time '(13818 19266) '(13818 19145))
1376 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1377 "Sat Sep 07 12:21:54 1998 +0200")
1380 (date-leap-year-p 2000)
1383 (time-to-day-in-year '(13818 19266))
1386 (time-to-number-of-days
1388 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1389 @result{} 4.146122685185185
1392 And finally, we have @code{safe-date-to-time}, which does the same as
1393 @code{date-to-time}, but returns a zero time if the date is
1394 syntactically malformed.
1396 The five data representations used are the following:
1400 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1401 12:21:54 1998 +0200"}.
1404 An internal Emacs time. For instance: @code{(13818 26466)}.
1407 A floating point representation of the internal Emacs time. For
1408 instance: @code{905595714.0}.
1411 An integer number representing the number of days since 00000101. For
1412 instance: @code{729644}.
1415 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1419 All the examples above represent the same moment.
1421 These are the functions available:
1425 Take a date and return a time.
1427 @item time-to-seconds
1428 Take a time and return seconds.
1430 @item seconds-to-time
1431 Take seconds and return a time.
1434 Take a time and return days.
1437 Take days and return a time.
1440 Take a date and return days.
1442 @item time-to-number-of-days
1443 Take a time and return the number of days that represents.
1445 @item safe-date-to-time
1446 Take a date and return a time. If the date is not syntactically valid,
1447 return a "zero" date.
1450 Take two times and say whether the first time is less (i. e., earlier)
1451 than the second time.
1454 Take a time and return a time saying how long it was since that time.
1457 Take two times and subtract the second from the first. I. e., return
1458 the time between the two times.
1461 Take two days and return the number of days between those two days.
1463 @item date-leap-year-p
1464 Take a year number and say whether it's a leap year.
1466 @item time-to-day-in-year
1467 Take a time and return the day number within the year that the time is
1476 This library deals with decoding and encoding Quoted-Printable text.
1478 Very briefly explained, qp encoding means translating all 8-bit
1479 characters (and lots of control characters) into things that look like
1480 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1483 The following functions are defined by the library:
1486 @item quoted-printable-decode-region
1487 @findex quoted-printable-decode-region
1488 QP-decode all the encoded text in the specified region.
1490 @item quoted-printable-decode-string
1491 @findex quoted-printable-decode-string
1492 Decode the QP-encoded text in a string and return the results.
1494 @item quoted-printable-encode-region
1495 @findex quoted-printable-encode-region
1496 QP-encode all the encodable characters in the specified region. The third
1497 optional parameter @var{fold} specifies whether to fold long lines.
1498 (Long here means 72.)
1500 @item quoted-printable-encode-string
1501 @findex quoted-printable-encode-string
1502 QP-encode all the encodable characters in a string and return the
1512 Base64 is an encoding that encodes three bytes into four characters,
1513 thereby increasing the size by about 33%. The alphabet used for
1514 encoding is very resistant to mangling during transit.
1516 The following functions are defined by this library:
1519 @item base64-encode-region
1520 @findex base64-encode-region
1521 base64 encode the selected region. Return the length of the encoded
1522 text. Optional third argument @var{no-line-break} means do not break
1523 long lines into shorter lines.
1525 @item base64-encode-string
1526 @findex base64-encode-string
1527 base64 encode a string and return the result.
1529 @item base64-decode-region
1530 @findex base64-decode-region
1531 base64 decode the selected region. Return the length of the decoded
1532 text. If the region can't be decoded, return @code{nil} and don't
1535 @item base64-decode-string
1536 @findex base64-decode-string
1537 base64 decode a string and return the result. If the string can't be
1538 decoded, @code{nil} is returned.
1549 @code{binhex} is an encoding that originated in Macintosh environments.
1550 The following function is supplied to deal with these:
1553 @item binhex-decode-region
1554 @findex binhex-decode-region
1555 Decode the encoded text in the region. If given a third parameter, only
1556 decode the @code{binhex} header and return the filename.
1565 @code{uuencode} is probably still the most popular encoding of binaries
1566 used on Usenet, although @code{base64} rules the mail world.
1568 The following function is supplied by this package:
1571 @item uudecode-decode-region
1572 @findex uudecode-decode-region
1573 Decode the text in the region.
1581 @code{yenc} is used for encoding binaries on Usenet. The following
1582 function is supplied by this package:
1585 @item yenc-decode-region
1586 @findex yenc-decode-region
1587 Decode the encoded text in the region.
1598 RFC1843 deals with mixing Chinese and ASCII characters in messages. In
1599 essence, RFC1843 switches between ASCII and Chinese by doing this:
1602 This sentence is in ASCII.
1603 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1606 Simple enough, and widely used in China.
1608 The following functions are available to handle this encoding:
1611 @item rfc1843-decode-region
1612 Decode HZ-encoded text in the region.
1614 @item rfc1843-decode-string
1615 Decode a HZ-encoded string and return the result.
1623 The @file{~/.mailcap} file is parsed by most @sc{mime}-aware message
1624 handlers and describes how elements are supposed to be displayed.
1625 Here's an example file:
1629 audio/wav; wavplayer %s
1630 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1633 This says that all image files should be displayed with @code{gimp},
1634 that WAVE audio files should be played by @code{wavplayer}, and that
1635 MS-WORD files should be inlined by @code{catdoc}.
1637 The @code{mailcap} library parses this file, and provides functions for
1641 @item mailcap-mime-data
1642 @vindex mailcap-mime-data
1643 This variable is an alist of alists containing backup viewing rules.
1647 Interface functions:
1650 @item mailcap-parse-mailcaps
1651 @findex mailcap-parse-mailcaps
1652 Parse the @file{~/.mailcap} file.
1654 @item mailcap-mime-info
1655 Takes a @sc{mime} type as its argument and returns the matching viewer.
1665 The Emacs @sc{mime} library implements handling of various elements
1666 according to a (somewhat) large number of RFCs, drafts and standards
1667 documents. This chapter lists the relevant ones. They can all be
1668 fetched from @uref{http://quimby.gnus.org/notes/}.
1673 Standard for the Format of ARPA Internet Text Messages.
1676 Standard for Interchange of USENET Messages
1679 Format of Internet Message Bodies
1685 Message Header Extensions for Non-ASCII Text
1688 Registration Procedures
1691 Conformance Criteria and Examples
1694 @sc{mime} Parameter Value and Encoded Word Extensions: Character Sets,
1695 Languages, and Continuations
1698 HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1701 @item draft-ietf-drums-msg-fmt-05.txt
1702 Draft for the successor of RFC822
1705 The @sc{mime} Multipart/Related Content-type
1708 The Multipart/Report Content Type for the Reporting of Mail System
1709 Administrative Messages
1712 Communicating Presentation Information in Internet Messages: The
1713 Content-Disposition Header Field
1716 Documentation of the text/plain format parameter for flowed text.
1732 @c coding: iso-8859-1