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
79 @acronym{MIME} messages.
81 This manual is directed at users who want to modify the behaviour of
82 the @acronym{MIME} encoding/decoding process or want a more detailed
83 picture of how the Emacs @acronym{MIME} library works, and people who want
84 to write functions and commands that manipulate @acronym{MIME} elements.
86 @acronym{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-@acronym{ASCII} Text), RFC2048 (Registration
90 Procedures), RFC2049 (Conformance Criteria and Examples). It is highly
91 recommended that anyone who intends writing @acronym{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 @acronym{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 @acronym{MIME} messages on a
110 The main idea is to first analyze a @acronym{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 @acronym{MIME} message.
116 * Non-MIME:: Analyzing a non-@acronym{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 @acronym{MIME} article. If given a multipart message, it will recursively
130 descend the message, following the structure, and return a tree of
131 @acronym{MIME} handles that describes the structure of the message.
135 @vindex mm-uu-configure-list
137 Gnus also understands some non-@acronym{MIME} attachments, such as
138 postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp,
139 diff. 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-@acronym{MIME} forwarded message.
178 @acronym{PGP} signed clear text.
181 @findex pgp-encrypted
182 @acronym{PGP} encrypted clear text.
186 @acronym{PGP} public keys.
189 @findex emacs-sources
190 @vindex mm-uu-emacs-sources-regexp
191 Emacs source code. This item works only in the groups matching
192 @code{mm-uu-emacs-sources-regexp}.
196 @vindex mm-uu-diff-groups-regexp
197 Patches. This is intended for groups where diffs of committed files
198 are automatically sent to. It only works in groups matching
199 @code{mm-uu-diff-groups-regexp}.
206 A @acronym{MIME} handle is a list that fully describes a @acronym{MIME}
209 The following macros can be used to access elements in a handle:
212 @item mm-handle-buffer
213 @findex mm-handle-buffer
214 Return the buffer that holds the contents of the undecoded @acronym{MIME}
218 @findex mm-handle-type
219 Return the parsed @code{Content-Type} of the part.
221 @item mm-handle-encoding
222 @findex mm-handle-encoding
223 Return the @code{Content-Transfer-Encoding} of the part.
225 @item mm-handle-undisplayer
226 @findex mm-handle-undisplayer
227 Return the object that can be used to remove the displayed part (if it
230 @item mm-handle-set-undisplayer
231 @findex mm-handle-set-undisplayer
232 Set the undisplayer object.
234 @item mm-handle-disposition
235 @findex mm-handle-disposition
236 Return the parsed @code{Content-Disposition} of the part.
238 @item mm-handle-disposition
239 @findex mm-handle-disposition
240 Return the description of the part.
242 @item mm-get-content-id
243 Returns the handle(s) referred to by @code{Content-ID}.
251 Functions for displaying, removing and saving.
254 @item mm-display-part
255 @findex mm-display-part
259 @findex mm-remove-part
260 Remove the part (if it has been displayed).
263 @findex mm-inlinable-p
264 Say whether a @acronym{MIME} type can be displayed inline.
266 @item mm-automatic-display-p
267 @findex mm-automatic-display-p
268 Say whether a @acronym{MIME} type should be displayed automatically.
270 @item mm-destroy-part
271 @findex mm-destroy-part
272 Free all resources occupied by a part.
276 Offer to save the part in a file.
280 Offer to pipe the part to some process.
282 @item mm-interactively-view-part
283 @findex mm-interactively-view-part
284 Prompt for a mailcap method to use to view the part.
289 @node Display Customization
290 @section Display Customization
294 @item mm-inline-media-tests
295 @vindex mm-inline-media-tests
296 This is an alist where the key is a @acronym{MIME} type, the second element
297 is a function to display the part @dfn{inline} (i.e., inside Emacs), and
298 the third element is a form to be @code{eval}ed to say whether the part
299 can be displayed inline.
301 This variable specifies whether a part @emph{can} be displayed inline,
302 and, if so, how to do it. It does not say whether parts are
303 @emph{actually} displayed inline.
305 @item mm-inlined-types
306 @vindex mm-inlined-types
307 This, on the other hand, says what types are to be displayed inline, if
308 they satisfy the conditions set by the variable above. It's a list of
309 @acronym{MIME} media types.
311 @item mm-automatic-display
312 @vindex mm-automatic-display
313 This is a list of types that are to be displayed ``automatically'', but
314 only if the above variable allows it. That is, only inlinable parts can
315 be displayed automatically.
317 @item mm-automatic-external-display
318 @vindex mm-automatic-external-display
319 This is a list of types that will be displayed automatically in an
322 @item mm-keep-viewer-alive-types
323 @vindex mm-keep-viewer-alive-types
324 This is a list of media types for which the external viewer will not
325 be killed when selecting a different article.
327 @item mm-attachment-override-types
328 @vindex mm-attachment-override-types
329 Some @acronym{MIME} agents create parts that have a content-disposition of
330 @samp{attachment}. This variable allows overriding that disposition and
331 displaying the part inline. (Note that the disposition is only
332 overridden if we are able to, and want to, display the part inline.)
334 @item mm-discouraged-alternatives
335 @vindex mm-discouraged-alternatives
336 List of @acronym{MIME} types that are discouraged when viewing
337 @samp{multipart/alternative}. Viewing agents are supposed to view the
338 last possible part of a message, as that is supposed to be the richest.
339 However, users may prefer other types instead, and this list says what
340 types are most unwanted. If, for instance, @samp{text/html} parts are
341 very unwanted, and @samp{text/richtext} parts are somewhat unwanted,
342 you could say something like:
345 (setq mm-discouraged-alternatives
346 '("text/html" "text/richtext")
348 (remove "text/html" mm-automatic-display))
351 @item mm-inline-large-images
352 @vindex mm-inline-large-images
353 When displaying inline images that are larger than the window, XEmacs
354 does not enable scrolling, which means that you cannot see the whole
355 image. To prevent this, the library tries to determine the image size
356 before displaying it inline, and if it doesn't fit the window, the
357 library will display it externally (e.g. with @samp{ImageMagick} or
358 @samp{xv}). Setting this variable to @code{t} disables this check and
359 makes the library display all inline images as inline, regardless of
362 @item mm-inline-override-types
363 @vindex mm-inline-override-types
364 @code{mm-inlined-types} may include regular expressions, for example to
365 specify that all @samp{text/.*} parts be displayed inline. If a user
366 prefers to have a type that matches such a regular expression be treated
367 as an attachment, that can be accomplished by setting this variable to a
368 list containing that type. For example assuming @code{mm-inlined-types}
369 includes @samp{text/.*}, then including @samp{text/html} in this
370 variable will cause @samp{text/html} parts to be treated as attachments.
372 @item mm-text-html-renderer
373 @vindex mm-text-html-renderer
374 This selects the function used to render @acronym{HTML}. The predefined
375 renderers are selected by the symbols @code{w3},
376 @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
377 information about emacs-w3m}, @code{links}, @code{lynx},
378 @code{w3m-standalone} or @code{html2text}. If @code{nil} use an
379 external viewer. You can also specify a function, which will be
380 called with a @acronym{MIME} handle as the argument.
382 @item mm-inline-text-html-with-images
383 @vindex mm-inline-text-html-with-images
384 Some @acronym{HTML} mails might have the trick of spammers using
385 @samp{<img>} tags. It is likely to be intended to verify whether you
386 have read the mail. You can prevent your personal informations from
387 leaking by setting this option to @code{nil} (which is the default).
388 It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
389 command @kbd{t} on the image anchor to show an image even if it is
390 @code{nil}.@footnote{The command @kbd{T} will load all images. If you
391 have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
394 @item mm-w3m-safe-url-regexp
395 @vindex mm-w3m-safe-url-regexp
396 A regular expression that matches safe URL names, i.e. URLs that are
397 unlikely to leak personal information when rendering @acronym{HTML}
398 email (the default value is @samp{\\`cid:}). If @code{nil} consider
401 @item mm-inline-text-html-with-w3m-keymap
402 @vindex mm-inline-text-html-with-w3m-keymap
403 You can use emacs-w3m command keys in the inlined text/html part by
404 setting this option to non-@code{nil}. The default value is @code{t}.
406 @item mm-external-terminal-program
407 @vindex mm-external-terminal-program
408 The program used to start an external terminal.
412 @node Files and Directories
413 @section Files and Directories
417 @item mm-default-directory
418 @vindex mm-default-directory
419 The default directory for saving attachments. If @code{nil} use
420 @code{default-directory}.
422 @item mm-tmp-directory
423 @vindex mm-tmp-directory
424 Directory for storing temporary files.
426 @item mm-file-name-rewrite-functions
427 @vindex mm-file-name-rewrite-functions
428 A list of functions used for rewriting file names of @acronym{MIME}
429 parts. Each function is applied successively to the file name.
430 Ready-made functions include
433 @item mm-file-name-delete-control
434 @findex mm-file-name-delete-control
435 Delete all control characters.
437 @item mm-file-name-delete-gotchas
438 @findex mm-file-name-delete-gotchas
439 Delete characters that could have unintended consequences when used
440 with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and
441 @samp{-}, @samp{.} as the first character.
443 @item mm-file-name-delete-whitespace
444 @findex mm-file-name-delete-whitespace
445 Remove all whitespace.
447 @item mm-file-name-trim-whitespace
448 @findex mm-file-name-trim-whitespace
449 Remove leading and trailing whitespace.
451 @item mm-file-name-collapse-whitespace
452 @findex mm-file-name-collapse-whitespace
453 Collapse multiple whitespace characters.
455 @item mm-file-name-replace-whitespace
456 @findex mm-file-name-replace-whitespace
457 @vindex mm-file-name-replace-whitespace
458 Replace whitespace with underscores. Set the variable
459 @code{mm-file-name-replace-whitespace} to any other string if you do
460 not like underscores.
463 The standard Emacs functions @code{capitalize}, @code{downcase},
464 @code{upcase} and @code{upcase-initials} might also prove useful.
466 @item mm-path-name-rewrite-functions
467 @vindex mm-path-name-rewrite-functions
468 List of functions used for rewriting the full file names of @acronym{MIME}
469 parts. This is used when viewing parts externally, and is meant for
470 transforming the absolute name so that non-compliant programs can find
471 the file where it's saved.
478 Here's an example viewer for displaying @code{text/enriched} inline:
481 (defun mm-display-enriched-inline (handle)
484 (mm-insert-part handle)
485 (save-window-excursion
486 (enriched-decode (point-min) (point-max))
487 (setq text (buffer-string))))
488 (mm-insert-inline handle text)))
491 We see that the function takes a @acronym{MIME} handle as its parameter. It
492 then goes to a temporary buffer, inserts the text of the part, does some
493 work on the text, stores the result, goes back to the buffer it was
494 called from and inserts the result.
496 The two important helper functions here are @code{mm-insert-part} and
497 @code{mm-insert-inline}. The first function inserts the text of the
498 handle in the current buffer. It handles charset and/or content
499 transfer decoding. The second function just inserts whatever text you
500 tell it to insert, but it also sets things up so that the text can be
501 ``undisplayed'' in a convenient manner.
507 @cindex MIME Composing
509 @cindex MIME Meta Language
511 Creating a @acronym{MIME} message is boring and non-trivial. Therefore, a
512 library called @code{mml} has been defined that parses a language called
513 MML (@acronym{MIME} Meta Language) and generates @acronym{MIME} messages.
515 @findex mml-generate-mime
516 The main interface function is @code{mml-generate-mime}. It will
517 examine the contents of the current (narrowed-to) buffer and return a
518 string containing the @acronym{MIME} message.
521 * Simple MML Example:: An example MML document.
522 * MML Definition:: All valid MML elements.
523 * Advanced MML Example:: Another example MML document.
524 * Encoding Customization:: Variables that affect encoding.
525 * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}.
526 * Conversion:: Going from @acronym{MIME} to MML and vice versa.
527 * Flowed text:: Soft and hard newlines.
531 @node Simple MML Example
532 @section Simple MML Example
534 Here's a simple @samp{multipart/alternative}:
537 <#multipart type=alternative>
538 This is a plain text part.
539 <#part type=text/enriched>
540 <center>This is a centered enriched part</center>
544 After running this through @code{mml-generate-mime}, we get this:
547 Content-Type: multipart/alternative; boundary="=-=-="
553 This is a plain text part.
556 Content-Type: text/enriched
559 <center>This is a centered enriched part</center>
566 @section MML Definition
568 The MML language is very simple. It looks a bit like an SGML
569 application, but it's not.
571 The main concept of MML is the @dfn{part}. Each part can be of a
572 different type or use a different charset. The way to delineate a part
573 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
574 with the @samp{<#multipart ...>} tag. Parts are ended by the
575 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
576 @samp{<#part ...>} tags are also closed by the next open tag.
578 There's also the @samp{<#external ...>} tag. These introduce
579 @samp{external/message-body} parts.
581 Each tag can contain zero or more parameters on the form
582 @samp{parameter=value}. The values may be enclosed in quotation marks,
583 but that's not necessary unless the value contains white space. So
584 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
586 The following parameters have meaning in MML; parameters that have no
587 meaning are ignored. The MML parameter names are the same as the
588 @acronym{MIME} parameter names; the things in the parentheses say which
589 header it will be used in.
593 The @acronym{MIME} type of the part (@code{Content-Type}).
596 Use the contents of the file in the body of the part
597 (@code{Content-Disposition}).
600 The contents of the body of the part are to be encoded in the character
601 set specified (@code{Content-Type}). @xref{Charset Translation}.
604 Might be used to suggest a file name if the part is to be saved
605 to a file (@code{Content-Type}).
608 Valid values are @samp{inline} and @samp{attachment}
609 (@code{Content-Disposition}).
612 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
613 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
617 A description of the part (@code{Content-Description}).
620 RFC822 date when the part was created (@code{Content-Disposition}).
622 @item modification-date
623 RFC822 date when the part was modified (@code{Content-Disposition}).
626 RFC822 date when the part was read (@code{Content-Disposition}).
629 Who to encrypt/sign the part to. This field is used to override any
630 auto-detection based on the To/CC headers.
633 Identity used to sign the part. This field is used to override the
637 The size (in octets) of the part (@code{Content-Disposition}).
640 What technology to sign this MML part with (@code{smime}, @code{pgp}
644 What technology to encrypt this MML part with (@code{smime},
645 @code{pgp} or @code{pgpmime})
649 Parameters for @samp{text/plain}:
653 Formatting parameter for the text, valid values include @samp{fixed}
654 (the default) and @samp{flowed}. Normally you do not specify this
655 manually, since it requires the textual body to be formatted in a
656 special way described in RFC 2646. @xref{Flowed text}.
659 Parameters for @samp{application/octet-stream}:
663 Type of the part; informal---meant for human readers
664 (@code{Content-Type}).
667 Parameters for @samp{message/external-body}:
671 A word indicating the supported access mechanism by which the file may
672 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
673 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
676 The RFC822 date after which the file may no longer be fetched.
677 (@code{Content-Type}.)
680 The size (in octets) of the file. (@code{Content-Type}.)
683 Valid values are @samp{read} and @samp{read-write}
684 (@code{Content-Type}).
688 Parameters for @samp{sign=smime}:
693 File containing key and certificate for signer.
697 Parameters for @samp{encrypt=smime}:
702 File containing certificate for recipient.
707 @node Advanced MML Example
708 @section Advanced MML Example
710 Here's a complex multipart message. It's a @samp{multipart/mixed} that
711 contains many parts, one of which is a @samp{multipart/alternative}.
714 <#multipart type=mixed>
715 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
716 <#multipart type=alternative>
717 This is a plain text part.
718 <#part type=text/enriched name=enriched.txt>
719 <center>This is a centered enriched part</center>
721 This is a new plain text part.
722 <#part disposition=attachment>
723 This plain text part is an attachment.
727 And this is the resulting @acronym{MIME} message:
730 Content-Type: multipart/mixed; boundary="=-=-="
738 Content-Type: image/jpeg;
740 Content-Disposition: inline;
742 Content-Transfer-Encoding: base64
744 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
745 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
746 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
747 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
748 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
749 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
750 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
751 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
752 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
753 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
754 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
755 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
756 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
757 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
758 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
759 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
760 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
763 Content-Type: multipart/alternative; boundary="==-=-="
769 This is a plain text part.
772 Content-Type: text/enriched;
776 <center>This is a centered enriched part</center>
782 This is a new plain text part.
785 Content-Disposition: attachment
788 This plain text part is an attachment.
793 @node Encoding Customization
794 @section Encoding Customization
798 @item mm-body-charset-encoding-alist
799 @vindex mm-body-charset-encoding-alist
800 Mapping from @acronym{MIME} charset to encoding to use. This variable is
801 usually used except, e.g., when other requirements force a specific
802 encoding (digitally signed messages require 7bit encodings). The
806 ((iso-2022-jp . 7bit)
807 (iso-2022-jp-2 . 7bit)
813 As an example, if you do not want to have ISO-8859-1 characters
814 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
815 this variable. You can override this setting on a per-message basis
816 by using the @code{encoding} MML tag (@pxref{MML Definition}).
818 @item mm-coding-system-priorities
819 @vindex mm-coding-system-priorities
820 Prioritize coding systems to use for outgoing messages. The default
821 is @code{nil}, which means to use the defaults in Emacs. It is a list of
822 coding system symbols (aliases of coding systems does not work, use
823 @kbd{M-x describe-coding-system} to make sure you are not specifying
824 an alias in this variable). For example, if you have configured Emacs
825 to prefer UTF-8, but wish that outgoing messages should be sent in
826 ISO-8859-1 if possible, you can set this variable to
827 @code{(iso-latin-1)}. You can override this setting on a per-message
828 basis by using the @code{charset} MML tag (@pxref{MML Definition}).
830 @item mm-content-transfer-encoding-defaults
831 @vindex mm-content-transfer-encoding-defaults
832 Mapping from @acronym{MIME} types to encoding to use. This variable is usually
833 used except, e.g., when other requirements force a safer encoding
834 (digitally signed messages require 7bit encoding). Besides the normal
835 @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
836 each case the most efficient of quoted-printable and base64 should be
837 used. You can override this setting on a per-message basis by using
838 the @code{encoding} MML tag (@pxref{MML Definition}).
840 @item mm-use-ultra-safe-encoding
841 @vindex mm-use-ultra-safe-encoding
842 When this is non-@code{nil}, it means that textual parts are encoded as
843 quoted-printable if they contain lines longer than 76 characters or
844 starting with "From " in the body. Non-7bit encodings (8bit, binary)
845 are generally disallowed. This reduce the probability that a non-8bit
846 clean MTA or MDA changes the message. This should never be set
847 directly, but bound by other functions when necessary (e.g., when
848 encoding messages that are to be digitally signed).
852 @node Charset Translation
853 @section Charset Translation
856 During translation from MML to @acronym{MIME}, for each @acronym{MIME} part which
857 has been composed inside Emacs, an appropriate charset has to be chosen.
859 @vindex mail-parse-charset
860 If you are running a non-@sc{mule} Emacs, this process is simple: If the
861 part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset
862 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
863 variable directly, though. If you want to change the default charset,
864 please consult the documentation of the package which you use to process
865 @acronym{MIME} messages.
866 @xref{Various Message Variables, , Various Message Variables, message,
867 Message Manual}, for example.)
868 If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is
874 @vindex mm-mime-mule-charset-alist
875 Things are slightly more complicated when running Emacs with @sc{mule}
876 support. In this case, a list of the @sc{mule} charsets used in the
877 part is obtained, and the @sc{mule} charsets are translated to @acronym{MIME}
878 charsets by consulting the variable @code{mm-mime-mule-charset-alist}.
879 If this results in a single @acronym{MIME} charset, this is used to encode
880 the part. But if the resulting list of @acronym{MIME} charsets contains more
881 than one element, two things can happen: If it is possible to encode the
882 part via UTF-8, this charset is used. (For this, Emacs must support
883 the @code{utf-8} coding system, and the part must consist entirely of
884 characters which have Unicode counterparts.) If UTF-8 is not available
885 for some reason, the part is split into several ones, so that each one
886 can be encoded with a single @acronym{MIME} charset. The part can only be
887 split at line boundaries, though---if more than one @acronym{MIME} charset is
888 required to encode a single line, it is not possible to encode the part.
890 When running Emacs with @sc{mule} support, the preferences for which
891 coding system to use is inherited from Emacs itself. This means that
892 if Emacs is set up to prefer UTF-8, it will be used when encoding
893 messages. You can modify this by altering the
894 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
897 The charset to be used can be overridden by setting the @code{charset}
898 MML tag (@pxref{MML Definition}) when composing the message.
900 The encoding of characters (quoted-printable, 8bit etc) is orthogonal
901 to the discussion here, and is controlled by the variables
902 @code{mm-body-charset-encoding-alist} and
903 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
910 A (multipart) @acronym{MIME} message can be converted to MML with the
911 @code{mime-to-mml} function. It works on the message in the current
912 buffer, and substitutes MML markup for @acronym{MIME} boundaries.
913 Non-textual parts do not have their contents in the buffer, but instead
914 have the contents in separate buffers that are referred to from the MML
918 An MML message can be converted back to @acronym{MIME} by the
919 @code{mml-to-mime} function.
921 These functions are in certain senses ``lossy''---you will not get back
922 an identical message if you run @code{mime-to-mml} and then
923 @code{mml-to-mime}. Not only will trivial things like the order of the
924 headers differ, but the contents of the headers may also be different.
925 For instance, the original message may use base64 encoding on text,
926 while @code{mml-to-mime} may decide to use quoted-printable encoding, and
929 In essence, however, these two functions should be the inverse of each
930 other. The resulting contents of the message should remain equivalent,
936 @cindex format=flowed
938 The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines}
939 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
940 emacs, Emacs Manual}) when encoding a message, and the
941 ``format=flowed'' Content-Type parameter when decoding a message.
943 On encoding text, lines terminated by soft newline characters are
944 filled together and wrapped after the column decided by
945 @code{fill-flowed-encode-column}. This variable controls how the text
946 will look in a client that does not support flowed text, the default
947 is to wrap after 66 characters. If hard newline characters are not
948 present in the buffer, no flow encoding occurs.
950 On decoding flowed text, lines with soft newline characters are filled
951 together and wrapped after the column decided by
952 @code{fill-flowed-display-column}. The default is to wrap after
958 @node Interface Functions
959 @chapter Interface Functions
960 @cindex interface functions
963 The @code{mail-parse} library is an abstraction over the actual
964 low-level libraries that are described in the next chapter.
966 Standards change, and so programs have to change to fit in the new
967 mold. For instance, RFC2045 describes a syntax for the
968 @code{Content-Type} header that only allows @acronym{ASCII} characters in the
969 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
970 for continuation headers and non-@acronym{ASCII} characters.
972 The traditional way to deal with this is just to update the library
973 functions to parse the new syntax. However, this is sometimes the wrong
974 thing to do. In some instances it may be vital to be able to understand
975 both the old syntax as well as the new syntax, and if there is only one
976 library, one must choose between the old version of the library and the
977 new version of the library.
979 The Emacs @acronym{MIME} library takes a different tack. It defines a
980 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
981 and so on) that parses strictly according to the corresponding
982 standard. However, normal programs would not use the functions
983 provided by these libraries directly, but instead use the functions
984 provided by the @code{mail-parse} library. The functions in this
985 library are just aliases to the corresponding functions in the latest
986 low-level libraries. Using this scheme, programs get a consistent
987 interface they can use, and library developers are free to create
988 write code that handles new standards.
990 The following functions are defined by this library:
993 @item mail-header-parse-content-type
994 @findex mail-header-parse-content-type
995 Parse a @code{Content-Type} header and return a list on the following
1000 (attribute1 . value1)
1001 (attribute2 . value2)
1008 (mail-header-parse-content-type
1009 "image/gif; name=\"b980912.gif\"")
1010 @result{} ("image/gif" (name . "b980912.gif"))
1013 @item mail-header-parse-content-disposition
1014 @findex mail-header-parse-content-disposition
1015 Parse a @code{Content-Disposition} header and return a list on the same
1016 format as the function above.
1018 @item mail-content-type-get
1019 @findex mail-content-type-get
1020 Takes two parameters---a list on the format above, and an attribute.
1021 Returns the value of the attribute.
1024 (mail-content-type-get
1025 '("image/gif" (name . "b980912.gif")) 'name)
1026 @result{} "b980912.gif"
1029 @item mail-header-encode-parameter
1030 @findex mail-header-encode-parameter
1031 Takes a parameter string and returns an encoded version of the string.
1032 This is used for parameters in headers like @code{Content-Type} and
1033 @code{Content-Disposition}.
1035 @item mail-header-remove-comments
1036 @findex mail-header-remove-comments
1037 Return a comment-free version of a header.
1040 (mail-header-remove-comments
1041 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1042 @result{} "Gnus/5.070027 "
1045 @item mail-header-remove-whitespace
1046 @findex mail-header-remove-whitespace
1047 Remove linear white space from a header. Space inside quoted strings
1048 and comments is preserved.
1051 (mail-header-remove-whitespace
1052 "image/gif; name=\"Name with spaces\"")
1053 @result{} "image/gif;name=\"Name with spaces\""
1056 @item mail-header-get-comment
1057 @findex mail-header-get-comment
1058 Return the last comment in a header.
1061 (mail-header-get-comment
1062 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1063 @result{} "Finnish Landrace"
1066 @item mail-header-parse-address
1067 @findex mail-header-parse-address
1068 Parse an address and return a list containing the mailbox and the
1072 (mail-header-parse-address
1073 "Hrvoje Niksic <hniksic@@srce.hr>")
1074 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1077 @item mail-header-parse-addresses
1078 @findex mail-header-parse-addresses
1079 Parse a string with list of addresses and return a list of elements like
1080 the one described above.
1083 (mail-header-parse-addresses
1084 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1085 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1086 ("sb@@metis.no" . "Steinar Bang"))
1089 @item mail-header-parse-date
1090 @findex mail-header-parse-date
1091 Parse a date string and return an Emacs time structure.
1093 @item mail-narrow-to-head
1094 @findex mail-narrow-to-head
1095 Narrow the buffer to the header section of the buffer. Point is placed
1096 at the beginning of the narrowed buffer.
1098 @item mail-header-narrow-to-field
1099 @findex mail-header-narrow-to-field
1100 Narrow the buffer to the header under point. Understands continuation
1103 @item mail-header-fold-field
1104 @findex mail-header-fold-field
1105 Fold the header under point.
1107 @item mail-header-unfold-field
1108 @findex mail-header-unfold-field
1109 Unfold the header under point.
1111 @item mail-header-field-value
1112 @findex mail-header-field-value
1113 Return the value of the field under point.
1115 @item mail-encode-encoded-word-region
1116 @findex mail-encode-encoded-word-region
1117 Encode the non-@acronym{ASCII} words in the region. For instance,
1118 @samp{Naïve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1120 @item mail-encode-encoded-word-buffer
1121 @findex mail-encode-encoded-word-buffer
1122 Encode the non-@acronym{ASCII} words in the current buffer. This function is
1123 meant to be called narrowed to the headers of a message.
1125 @item mail-encode-encoded-word-string
1126 @findex mail-encode-encoded-word-string
1127 Encode the words that need encoding in a string, and return the result.
1130 (mail-encode-encoded-word-string
1131 "This is naïve, baby")
1132 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1135 @item mail-decode-encoded-word-region
1136 @findex mail-decode-encoded-word-region
1137 Decode the encoded words in the region.
1139 @item mail-decode-encoded-word-string
1140 @findex mail-decode-encoded-word-string
1141 Decode the encoded words in the string and return the result.
1144 (mail-decode-encoded-word-string
1145 "This is =?iso-8859-1?q?na=EFve,?= baby")
1146 @result{} "This is naïve, baby"
1151 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1152 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1153 in the subsequent sections.
1157 @node Basic Functions
1158 @chapter Basic Functions
1160 This chapter describes the basic, ground-level functions for parsing and
1161 handling. Covered here is parsing @code{From} lines, removing comments
1162 from header lines, decoding encoded words, parsing date headers and so
1163 on. High-level functionality is dealt with in the next chapter
1164 (@pxref{Decoding and Viewing}).
1167 * rfc2045:: Encoding @code{Content-Type} headers.
1168 * rfc2231:: Parsing @code{Content-Type} headers.
1169 * ietf-drums:: Handling mail headers defined by RFC822bis.
1170 * rfc2047:: En/decoding encoded words in headers.
1171 * time-date:: Functions for parsing dates and manipulating time.
1172 * qp:: Quoted-Printable en/decoding.
1173 * base64:: Base64 en/decoding.
1174 * binhex:: Binhex decoding.
1175 * uudecode:: Uuencode decoding.
1176 * yenc:: Yenc decoding.
1177 * rfc1843:: Decoding HZ-encoded text.
1178 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1185 RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would
1186 imagine that there would be a lot to implement. But there isn't, since
1187 most of the implementation details are delegated to the subsequent
1190 So @file{rfc2045.el} has only a single function:
1193 @item rfc2045-encode-string
1194 @findex rfc2045-encode-string
1195 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1196 @var{value} will be quoted if there are non-safe characters in it.
1203 RFC2231 defines a syntax for the @code{Content-Type} and
1204 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1205 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1208 In short, these headers look something like this:
1211 Content-Type: application/x-stuff;
1212 title*0*=us-ascii'en'This%20is%20even%20more%20;
1213 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1217 They usually aren't this bad, though.
1219 The following functions are defined by this library:
1222 @item rfc2231-parse-string
1223 @findex rfc2231-parse-string
1224 Parse a @code{Content-Type} header and return a list describing its
1228 (rfc2231-parse-string
1229 "application/x-stuff;
1230 title*0*=us-ascii'en'This%20is%20even%20more%20;
1231 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1232 title*2=\"isn't it!\"")
1233 @result{} ("application/x-stuff"
1234 (title . "This is even more ***fun*** isn't it!"))
1237 @item rfc2231-get-value
1238 @findex rfc2231-get-value
1239 Takes one of the lists on the format above and returns
1240 the value of the specified attribute.
1242 @item rfc2231-encode-string
1243 @findex rfc2231-encode-string
1244 Encode a parameter in headers likes @code{Content-Type} and
1245 @code{Content-Disposition}.
1253 @dfn{drums} is an IETF working group that is working on the replacement
1256 The functions provided by this library include:
1259 @item ietf-drums-remove-comments
1260 @findex ietf-drums-remove-comments
1261 Remove the comments from the argument and return the results.
1263 @item ietf-drums-remove-whitespace
1264 @findex ietf-drums-remove-whitespace
1265 Remove linear white space from the string and return the results.
1266 Spaces inside quoted strings and comments are left untouched.
1268 @item ietf-drums-get-comment
1269 @findex ietf-drums-get-comment
1270 Return the last most comment from the string.
1272 @item ietf-drums-parse-address
1273 @findex ietf-drums-parse-address
1274 Parse an address string and return a list that contains the mailbox and
1275 the plain text name.
1277 @item ietf-drums-parse-addresses
1278 @findex ietf-drums-parse-addresses
1279 Parse a string that contains any number of comma-separated addresses and
1280 return a list that contains mailbox/plain text pairs.
1282 @item ietf-drums-parse-date
1283 @findex ietf-drums-parse-date
1284 Parse a date string and return an Emacs time structure.
1286 @item ietf-drums-narrow-to-header
1287 @findex ietf-drums-narrow-to-header
1288 Narrow the buffer to the header section of the current buffer.
1296 RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how
1297 non-@acronym{ASCII} text in headers are to be encoded. This is actually rather
1298 complicated, so a number of variables are necessary to tweak what this
1301 The following variables are tweakable:
1304 @item rfc2047-default-charset
1305 @vindex rfc2047-default-charset
1306 Characters in this charset should not be decoded by this library.
1307 This defaults to @code{iso-8859-1}.
1309 @item rfc2047-header-encoding-alist
1310 @vindex rfc2047-header-encoding-alist
1311 This is an alist of header / encoding-type pairs. Its main purpose is
1312 to prevent encoding of certain headers.
1314 The keys can either be header regexps, or @code{t}.
1316 The values can be either @code{nil}, in which case the header(s) in
1317 question won't be encoded, or @code{mime}, which means that they will be
1320 @item rfc2047-charset-encoding-alist
1321 @vindex rfc2047-charset-encoding-alist
1322 RFC2047 specifies two forms of encoding---@code{Q} (a
1323 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1324 specifies which charset should use which encoding.
1326 @item rfc2047-encoding-function-alist
1327 @vindex rfc2047-encoding-function-alist
1328 This is an alist of encoding / function pairs. The encodings are
1329 @code{Q}, @code{B} and @code{nil}.
1331 @item rfc2047-q-encoding-alist
1332 @vindex rfc2047-q-encoding-alist
1333 The @code{Q} encoding isn't quite the same for all headers. Some
1334 headers allow a narrower range of characters, and that is what this
1335 variable is for. It's an alist of header regexps / allowable character
1338 @item rfc2047-encoded-word-regexp
1339 @vindex rfc2047-encoded-word-regexp
1340 When decoding words, this library looks for matches to this regexp.
1344 Those were the variables, and these are this functions:
1347 @item rfc2047-narrow-to-field
1348 @findex rfc2047-narrow-to-field
1349 Narrow the buffer to the header on the current line.
1351 @item rfc2047-encode-message-header
1352 @findex rfc2047-encode-message-header
1353 Should be called narrowed to the header of a message. Encodes according
1354 to @code{rfc2047-header-encoding-alist}.
1356 @item rfc2047-encode-region
1357 @findex rfc2047-encode-region
1358 Encodes all encodable words in the region specified.
1360 @item rfc2047-encode-string
1361 @findex rfc2047-encode-string
1362 Encode a string and return the results.
1364 @item rfc2047-decode-region
1365 @findex rfc2047-decode-region
1366 Decode the encoded words in the region.
1368 @item rfc2047-decode-string
1369 @findex rfc2047-decode-string
1370 Decode a string and return the results.
1378 While not really a part of the @acronym{MIME} library, it is convenient to
1379 document this library here. It deals with parsing @code{Date} headers
1380 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1383 These functions convert between five formats: A date string, an Emacs
1384 time structure, a decoded time list, a second number, and a day number.
1386 Here's a bunch of time/date/second/day examples:
1389 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1390 @result{} (54 21 12 12 9 1998 6 nil 7200)
1392 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1393 @result{} (13818 19266)
1395 (time-to-seconds '(13818 19266))
1396 @result{} 905595714.0
1398 (seconds-to-time 905595714.0)
1399 @result{} (13818 19266 0)
1401 (time-to-days '(13818 19266))
1404 (days-to-time 729644)
1405 @result{} (961933 65536)
1407 (time-since '(13818 19266))
1410 (time-less-p '(13818 19266) '(13818 19145))
1413 (subtract-time '(13818 19266) '(13818 19145))
1416 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1417 "Sat Sep 07 12:21:54 1998 +0200")
1420 (date-leap-year-p 2000)
1423 (time-to-day-in-year '(13818 19266))
1426 (time-to-number-of-days
1428 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1429 @result{} 4.146122685185185
1432 And finally, we have @code{safe-date-to-time}, which does the same as
1433 @code{date-to-time}, but returns a zero time if the date is
1434 syntactically malformed.
1436 The five data representations used are the following:
1440 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1441 12:21:54 1998 +0200"}.
1444 An internal Emacs time. For instance: @code{(13818 26466)}.
1447 A floating point representation of the internal Emacs time. For
1448 instance: @code{905595714.0}.
1451 An integer number representing the number of days since 00000101. For
1452 instance: @code{729644}.
1455 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1459 All the examples above represent the same moment.
1461 These are the functions available:
1465 Take a date and return a time.
1467 @item time-to-seconds
1468 Take a time and return seconds.
1470 @item seconds-to-time
1471 Take seconds and return a time.
1474 Take a time and return days.
1477 Take days and return a time.
1480 Take a date and return days.
1482 @item time-to-number-of-days
1483 Take a time and return the number of days that represents.
1485 @item safe-date-to-time
1486 Take a date and return a time. If the date is not syntactically valid,
1487 return a ``zero'' date.
1490 Take two times and say whether the first time is less (i. e., earlier)
1491 than the second time.
1494 Take a time and return a time saying how long it was since that time.
1497 Take two times and subtract the second from the first. I. e., return
1498 the time between the two times.
1501 Take two days and return the number of days between those two days.
1503 @item date-leap-year-p
1504 Take a year number and say whether it's a leap year.
1506 @item time-to-day-in-year
1507 Take a time and return the day number within the year that the time is
1516 This library deals with decoding and encoding Quoted-Printable text.
1518 Very briefly explained, qp encoding means translating all 8-bit
1519 characters (and lots of control characters) into things that look like
1520 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1523 The following functions are defined by the library:
1526 @item quoted-printable-decode-region
1527 @findex quoted-printable-decode-region
1528 QP-decode all the encoded text in the specified region.
1530 @item quoted-printable-decode-string
1531 @findex quoted-printable-decode-string
1532 Decode the QP-encoded text in a string and return the results.
1534 @item quoted-printable-encode-region
1535 @findex quoted-printable-encode-region
1536 QP-encode all the encodable characters in the specified region. The third
1537 optional parameter @var{fold} specifies whether to fold long lines.
1538 (Long here means 72.)
1540 @item quoted-printable-encode-string
1541 @findex quoted-printable-encode-string
1542 QP-encode all the encodable characters in a string and return the
1552 Base64 is an encoding that encodes three bytes into four characters,
1553 thereby increasing the size by about 33%. The alphabet used for
1554 encoding is very resistant to mangling during transit.
1556 The following functions are defined by this library:
1559 @item base64-encode-region
1560 @findex base64-encode-region
1561 base64 encode the selected region. Return the length of the encoded
1562 text. Optional third argument @var{no-line-break} means do not break
1563 long lines into shorter lines.
1565 @item base64-encode-string
1566 @findex base64-encode-string
1567 base64 encode a string and return the result.
1569 @item base64-decode-region
1570 @findex base64-decode-region
1571 base64 decode the selected region. Return the length of the decoded
1572 text. If the region can't be decoded, return @code{nil} and don't
1575 @item base64-decode-string
1576 @findex base64-decode-string
1577 base64 decode a string and return the result. If the string can't be
1578 decoded, @code{nil} is returned.
1589 @code{binhex} is an encoding that originated in Macintosh environments.
1590 The following function is supplied to deal with these:
1593 @item binhex-decode-region
1594 @findex binhex-decode-region
1595 Decode the encoded text in the region. If given a third parameter, only
1596 decode the @code{binhex} header and return the filename.
1605 @code{uuencode} is probably still the most popular encoding of binaries
1606 used on Usenet, although @code{base64} rules the mail world.
1608 The following function is supplied by this package:
1611 @item uudecode-decode-region
1612 @findex uudecode-decode-region
1613 Decode the text in the region.
1621 @code{yenc} is used for encoding binaries on Usenet. The following
1622 function is supplied by this package:
1625 @item yenc-decode-region
1626 @findex yenc-decode-region
1627 Decode the encoded text in the region.
1638 RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In
1639 essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this:
1642 This sentence is in @acronym{ASCII}.
1643 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1646 Simple enough, and widely used in China.
1648 The following functions are available to handle this encoding:
1651 @item rfc1843-decode-region
1652 Decode HZ-encoded text in the region.
1654 @item rfc1843-decode-string
1655 Decode a HZ-encoded string and return the result.
1663 The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message
1664 handlers and describes how elements are supposed to be displayed.
1665 Here's an example file:
1669 audio/wav; wavplayer %s
1670 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1673 This says that all image files should be displayed with @code{gimp},
1674 that WAVE audio files should be played by @code{wavplayer}, and that
1675 MS-WORD files should be inlined by @code{catdoc}.
1677 The @code{mailcap} library parses this file, and provides functions for
1681 @item mailcap-mime-data
1682 @vindex mailcap-mime-data
1683 This variable is an alist of alists containing backup viewing rules.
1687 Interface functions:
1690 @item mailcap-parse-mailcaps
1691 @findex mailcap-parse-mailcaps
1692 Parse the @file{~/.mailcap} file.
1694 @item mailcap-mime-info
1695 Takes a @acronym{MIME} type as its argument and returns the matching viewer.
1705 The Emacs @acronym{MIME} library implements handling of various elements
1706 according to a (somewhat) large number of RFCs, drafts and standards
1707 documents. This chapter lists the relevant ones. They can all be
1708 fetched from @uref{http://quimby.gnus.org/notes/}.
1713 Standard for the Format of ARPA Internet Text Messages.
1716 Standard for Interchange of USENET Messages
1719 Format of Internet Message Bodies
1725 Message Header Extensions for Non-@acronym{ASCII} Text
1728 Registration Procedures
1731 Conformance Criteria and Examples
1734 @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets,
1735 Languages, and Continuations
1738 HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1739 @acronym{ASCII} characters
1741 @item draft-ietf-drums-msg-fmt-05.txt
1742 Draft for the successor of RFC822
1745 The @acronym{MIME} Multipart/Related Content-type
1748 The Multipart/Report Content Type for the Reporting of Mail System
1749 Administrative Messages
1752 Communicating Presentation Information in Internet Messages: The
1753 Content-Disposition Header Field
1756 Documentation of the text/plain format parameter for flowed text.
1772 @c coding: iso-8859-1