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:: @acronym{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.
410 @item mm-enable-external
411 @vindex mm-enable-external
412 Indicate whether external MIME handlers should be used.
414 If @code{t}, all defined external MIME handlers are used. If
415 @code{nil}, files are saved to disk (@code{mailcap-save-binary-file}).
416 If it is the symbol @code{ask}, you are prompted before the external
417 @acronym{MIME} handler is invoked.
419 When you launch an attachment through mailcap (@pxref{mailcap}) an
420 attempt is made to use a safe viewer with the safest options--this isn't
421 the case if you save it to disk and launch it in a different way
422 (command line or double-clicking). Anyhow, if you want to be sure not
423 to launch any external programs, set this variable to @code{nil} or
428 @node Files and Directories
429 @section Files and Directories
433 @item mm-default-directory
434 @vindex mm-default-directory
435 The default directory for saving attachments. If @code{nil} use
436 @code{default-directory}.
438 @item mm-tmp-directory
439 @vindex mm-tmp-directory
440 Directory for storing temporary files.
442 @item mm-file-name-rewrite-functions
443 @vindex mm-file-name-rewrite-functions
444 A list of functions used for rewriting file names of @acronym{MIME}
445 parts. Each function is applied successively to the file name.
446 Ready-made functions include
449 @item mm-file-name-delete-control
450 @findex mm-file-name-delete-control
451 Delete all control characters.
453 @item mm-file-name-delete-gotchas
454 @findex mm-file-name-delete-gotchas
455 Delete characters that could have unintended consequences when used
456 with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and
457 @samp{-}, @samp{.} as the first character.
459 @item mm-file-name-delete-whitespace
460 @findex mm-file-name-delete-whitespace
461 Remove all whitespace.
463 @item mm-file-name-trim-whitespace
464 @findex mm-file-name-trim-whitespace
465 Remove leading and trailing whitespace.
467 @item mm-file-name-collapse-whitespace
468 @findex mm-file-name-collapse-whitespace
469 Collapse multiple whitespace characters.
471 @item mm-file-name-replace-whitespace
472 @findex mm-file-name-replace-whitespace
473 @vindex mm-file-name-replace-whitespace
474 Replace whitespace with underscores. Set the variable
475 @code{mm-file-name-replace-whitespace} to any other string if you do
476 not like underscores.
479 The standard Emacs functions @code{capitalize}, @code{downcase},
480 @code{upcase} and @code{upcase-initials} might also prove useful.
482 @item mm-path-name-rewrite-functions
483 @vindex mm-path-name-rewrite-functions
484 List of functions used for rewriting the full file names of @acronym{MIME}
485 parts. This is used when viewing parts externally, and is meant for
486 transforming the absolute name so that non-compliant programs can find
487 the file where it's saved.
494 Here's an example viewer for displaying @code{text/enriched} inline:
497 (defun mm-display-enriched-inline (handle)
500 (mm-insert-part handle)
501 (save-window-excursion
502 (enriched-decode (point-min) (point-max))
503 (setq text (buffer-string))))
504 (mm-insert-inline handle text)))
507 We see that the function takes a @acronym{MIME} handle as its parameter. It
508 then goes to a temporary buffer, inserts the text of the part, does some
509 work on the text, stores the result, goes back to the buffer it was
510 called from and inserts the result.
512 The two important helper functions here are @code{mm-insert-part} and
513 @code{mm-insert-inline}. The first function inserts the text of the
514 handle in the current buffer. It handles charset and/or content
515 transfer decoding. The second function just inserts whatever text you
516 tell it to insert, but it also sets things up so that the text can be
517 ``undisplayed'' in a convenient manner.
523 @cindex MIME Composing
525 @cindex MIME Meta Language
527 Creating a @acronym{MIME} message is boring and non-trivial. Therefore,
528 a library called @code{mml} has been defined that parses a language
529 called @acronym{MML} (@acronym{MIME} Meta Language) and generates
530 @acronym{MIME} messages.
532 @findex mml-generate-mime
533 The main interface function is @code{mml-generate-mime}. It will
534 examine the contents of the current (narrowed-to) buffer and return a
535 string containing the @acronym{MIME} message.
538 * Simple MML Example:: An example @acronym{MML} document.
539 * MML Definition:: All valid @acronym{MML} elements.
540 * Advanced MML Example:: Another example @acronym{MML} document.
541 * Encoding Customization:: Variables that affect encoding.
542 * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}.
543 * Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa.
544 * Flowed text:: Soft and hard newlines.
548 @node Simple MML Example
549 @section Simple MML Example
551 Here's a simple @samp{multipart/alternative}:
554 <#multipart type=alternative>
555 This is a plain text part.
556 <#part type=text/enriched>
557 <center>This is a centered enriched part</center>
561 After running this through @code{mml-generate-mime}, we get this:
564 Content-Type: multipart/alternative; boundary="=-=-="
570 This is a plain text part.
573 Content-Type: text/enriched
576 <center>This is a centered enriched part</center>
583 @section MML Definition
585 The @acronym{MML} language is very simple. It looks a bit like an SGML
586 application, but it's not.
588 The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a
589 different type or use a different charset. The way to delineate a part
590 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
591 with the @samp{<#multipart ...>} tag. Parts are ended by the
592 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
593 @samp{<#part ...>} tags are also closed by the next open tag.
595 There's also the @samp{<#external ...>} tag. These introduce
596 @samp{external/message-body} parts.
598 Each tag can contain zero or more parameters on the form
599 @samp{parameter=value}. The values may be enclosed in quotation marks,
600 but that's not necessary unless the value contains white space. So
601 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
603 The following parameters have meaning in @acronym{MML}; parameters that have no
604 meaning are ignored. The @acronym{MML} parameter names are the same as the
605 @acronym{MIME} parameter names; the things in the parentheses say which
606 header it will be used in.
610 The @acronym{MIME} type of the part (@code{Content-Type}).
613 Use the contents of the file in the body of the part
614 (@code{Content-Disposition}).
617 The contents of the body of the part are to be encoded in the character
618 set specified (@code{Content-Type}). @xref{Charset Translation}.
621 Might be used to suggest a file name if the part is to be saved
622 to a file (@code{Content-Type}).
625 Valid values are @samp{inline} and @samp{attachment}
626 (@code{Content-Disposition}).
629 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
630 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
634 A description of the part (@code{Content-Description}).
637 RFC822 date when the part was created (@code{Content-Disposition}).
639 @item modification-date
640 RFC822 date when the part was modified (@code{Content-Disposition}).
643 RFC822 date when the part was read (@code{Content-Disposition}).
646 Who to encrypt/sign the part to. This field is used to override any
647 auto-detection based on the To/CC headers.
650 Identity used to sign the part. This field is used to override the
654 The size (in octets) of the part (@code{Content-Disposition}).
657 What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp}
661 What technology to encrypt this @acronym{MML} part with (@code{smime},
662 @code{pgp} or @code{pgpmime})
666 Parameters for @samp{text/plain}:
670 Formatting parameter for the text, valid values include @samp{fixed}
671 (the default) and @samp{flowed}. Normally you do not specify this
672 manually, since it requires the textual body to be formatted in a
673 special way described in RFC 2646. @xref{Flowed text}.
676 Parameters for @samp{application/octet-stream}:
680 Type of the part; informal---meant for human readers
681 (@code{Content-Type}).
684 Parameters for @samp{message/external-body}:
688 A word indicating the supported access mechanism by which the file may
689 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
690 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
693 The RFC822 date after which the file may no longer be fetched.
694 (@code{Content-Type}.)
697 The size (in octets) of the file. (@code{Content-Type}.)
700 Valid values are @samp{read} and @samp{read-write}
701 (@code{Content-Type}).
705 Parameters for @samp{sign=smime}:
710 File containing key and certificate for signer.
714 Parameters for @samp{encrypt=smime}:
719 File containing certificate for recipient.
724 @node Advanced MML Example
725 @section Advanced MML Example
727 Here's a complex multipart message. It's a @samp{multipart/mixed} that
728 contains many parts, one of which is a @samp{multipart/alternative}.
731 <#multipart type=mixed>
732 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
733 <#multipart type=alternative>
734 This is a plain text part.
735 <#part type=text/enriched name=enriched.txt>
736 <center>This is a centered enriched part</center>
738 This is a new plain text part.
739 <#part disposition=attachment>
740 This plain text part is an attachment.
744 And this is the resulting @acronym{MIME} message:
747 Content-Type: multipart/mixed; boundary="=-=-="
755 Content-Type: image/jpeg;
757 Content-Disposition: inline;
759 Content-Transfer-Encoding: base64
761 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
762 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
763 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
764 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
765 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
766 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
767 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
768 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
769 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
770 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
771 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
772 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
773 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
774 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
775 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
776 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
777 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
780 Content-Type: multipart/alternative; boundary="==-=-="
786 This is a plain text part.
789 Content-Type: text/enriched;
793 <center>This is a centered enriched part</center>
799 This is a new plain text part.
802 Content-Disposition: attachment
805 This plain text part is an attachment.
810 @node Encoding Customization
811 @section Encoding Customization
815 @item mm-body-charset-encoding-alist
816 @vindex mm-body-charset-encoding-alist
817 Mapping from @acronym{MIME} charset to encoding to use. This variable is
818 usually used except, e.g., when other requirements force a specific
819 encoding (digitally signed messages require 7bit encodings). The
823 ((iso-2022-jp . 7bit)
824 (iso-2022-jp-2 . 7bit)
830 As an example, if you do not want to have ISO-8859-1 characters
831 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
832 this variable. You can override this setting on a per-message basis
833 by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
835 @item mm-coding-system-priorities
836 @vindex mm-coding-system-priorities
837 Prioritize coding systems to use for outgoing messages. The default
838 is @code{nil}, which means to use the defaults in Emacs. It is a list of
839 coding system symbols (aliases of coding systems does not work, use
840 @kbd{M-x describe-coding-system} to make sure you are not specifying
841 an alias in this variable). For example, if you have configured Emacs
842 to prefer UTF-8, but wish that outgoing messages should be sent in
843 ISO-8859-1 if possible, you can set this variable to
844 @code{(iso-latin-1)}. You can override this setting on a per-message
845 basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}).
847 @item mm-content-transfer-encoding-defaults
848 @vindex mm-content-transfer-encoding-defaults
849 Mapping from @acronym{MIME} types to encoding to use. This variable is usually
850 used except, e.g., when other requirements force a safer encoding
851 (digitally signed messages require 7bit encoding). Besides the normal
852 @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
853 each case the most efficient of quoted-printable and base64 should be
854 used. You can override this setting on a per-message basis by using
855 the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
857 @item mm-use-ultra-safe-encoding
858 @vindex mm-use-ultra-safe-encoding
859 When this is non-@code{nil}, it means that textual parts are encoded as
860 quoted-printable if they contain lines longer than 76 characters or
861 starting with "From " in the body. Non-7bit encodings (8bit, binary)
862 are generally disallowed. This reduce the probability that a non-8bit
863 clean MTA or MDA changes the message. This should never be set
864 directly, but bound by other functions when necessary (e.g., when
865 encoding messages that are to be digitally signed).
869 @node Charset Translation
870 @section Charset Translation
873 During translation from @acronym{MML} to @acronym{MIME}, for each
874 @acronym{MIME} part which has been composed inside Emacs, an appropriate
875 charset has to be chosen.
877 @vindex mail-parse-charset
878 If you are running a non-@sc{mule} Emacs, this process is simple: If the
879 part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset
880 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
881 variable directly, though. If you want to change the default charset,
882 please consult the documentation of the package which you use to process
883 @acronym{MIME} messages.
884 @xref{Various Message Variables, , Various Message Variables, message,
885 Message Manual}, for example.)
886 If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is
892 @vindex mm-mime-mule-charset-alist
893 Things are slightly more complicated when running Emacs with @sc{mule}
894 support. In this case, a list of the @sc{mule} charsets used in the
895 part is obtained, and the @sc{mule} charsets are translated to @acronym{MIME}
896 charsets by consulting the variable @code{mm-mime-mule-charset-alist}.
897 If this results in a single @acronym{MIME} charset, this is used to encode
898 the part. But if the resulting list of @acronym{MIME} charsets contains more
899 than one element, two things can happen: If it is possible to encode the
900 part via UTF-8, this charset is used. (For this, Emacs must support
901 the @code{utf-8} coding system, and the part must consist entirely of
902 characters which have Unicode counterparts.) If UTF-8 is not available
903 for some reason, the part is split into several ones, so that each one
904 can be encoded with a single @acronym{MIME} charset. The part can only be
905 split at line boundaries, though---if more than one @acronym{MIME} charset is
906 required to encode a single line, it is not possible to encode the part.
908 When running Emacs with @sc{mule} support, the preferences for which
909 coding system to use is inherited from Emacs itself. This means that
910 if Emacs is set up to prefer UTF-8, it will be used when encoding
911 messages. You can modify this by altering the
912 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
915 The charset to be used can be overridden by setting the @code{charset}
916 @acronym{MML} tag (@pxref{MML Definition}) when composing the message.
918 The encoding of characters (quoted-printable, 8bit etc) is orthogonal
919 to the discussion here, and is controlled by the variables
920 @code{mm-body-charset-encoding-alist} and
921 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
928 A (multipart) @acronym{MIME} message can be converted to @acronym{MML}
929 with the @code{mime-to-mml} function. It works on the message in the
930 current buffer, and substitutes @acronym{MML} markup for @acronym{MIME}
931 boundaries. Non-textual parts do not have their contents in the buffer,
932 but instead have the contents in separate buffers that are referred to
933 from the @acronym{MML} tags.
936 An @acronym{MML} message can be converted back to @acronym{MIME} by the
937 @code{mml-to-mime} function.
939 These functions are in certain senses ``lossy''---you will not get back
940 an identical message if you run @code{mime-to-mml} and then
941 @code{mml-to-mime}. Not only will trivial things like the order of the
942 headers differ, but the contents of the headers may also be different.
943 For instance, the original message may use base64 encoding on text,
944 while @code{mml-to-mime} may decide to use quoted-printable encoding, and
947 In essence, however, these two functions should be the inverse of each
948 other. The resulting contents of the message should remain equivalent,
954 @cindex format=flowed
956 The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines}
957 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
958 emacs, Emacs Manual}) when encoding a message, and the
959 ``format=flowed'' Content-Type parameter when decoding a message.
961 On encoding text, regardless of @code{use-hard-newlines}, lines
962 terminated by soft newline characters are filled together and wrapped
963 after the column decided by @code{fill-flowed-encode-column}.
964 Quotation marks (matching @samp{^>* ?}) are respected. The variable
965 controls how the text will look in a client that does not support
966 flowed text, the default is to wrap after 66 characters. If hard
967 newline characters are not present in the buffer, no flow encoding
970 On decoding flowed text, lines with soft newline characters are filled
971 together and wrapped after the column decided by
972 @code{fill-flowed-display-column}. The default is to wrap after
978 @node Interface Functions
979 @chapter Interface Functions
980 @cindex interface functions
983 The @code{mail-parse} library is an abstraction over the actual
984 low-level libraries that are described in the next chapter.
986 Standards change, and so programs have to change to fit in the new
987 mold. For instance, RFC2045 describes a syntax for the
988 @code{Content-Type} header that only allows @acronym{ASCII} characters in the
989 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
990 for continuation headers and non-@acronym{ASCII} characters.
992 The traditional way to deal with this is just to update the library
993 functions to parse the new syntax. However, this is sometimes the wrong
994 thing to do. In some instances it may be vital to be able to understand
995 both the old syntax as well as the new syntax, and if there is only one
996 library, one must choose between the old version of the library and the
997 new version of the library.
999 The Emacs @acronym{MIME} library takes a different tack. It defines a
1000 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
1001 and so on) that parses strictly according to the corresponding
1002 standard. However, normal programs would not use the functions
1003 provided by these libraries directly, but instead use the functions
1004 provided by the @code{mail-parse} library. The functions in this
1005 library are just aliases to the corresponding functions in the latest
1006 low-level libraries. Using this scheme, programs get a consistent
1007 interface they can use, and library developers are free to create
1008 write code that handles new standards.
1010 The following functions are defined by this library:
1013 @item mail-header-parse-content-type
1014 @findex mail-header-parse-content-type
1015 Parse a @code{Content-Type} header and return a list on the following
1020 (attribute1 . value1)
1021 (attribute2 . value2)
1028 (mail-header-parse-content-type
1029 "image/gif; name=\"b980912.gif\"")
1030 @result{} ("image/gif" (name . "b980912.gif"))
1033 @item mail-header-parse-content-disposition
1034 @findex mail-header-parse-content-disposition
1035 Parse a @code{Content-Disposition} header and return a list on the same
1036 format as the function above.
1038 @item mail-content-type-get
1039 @findex mail-content-type-get
1040 Takes two parameters---a list on the format above, and an attribute.
1041 Returns the value of the attribute.
1044 (mail-content-type-get
1045 '("image/gif" (name . "b980912.gif")) 'name)
1046 @result{} "b980912.gif"
1049 @item mail-header-encode-parameter
1050 @findex mail-header-encode-parameter
1051 Takes a parameter string and returns an encoded version of the string.
1052 This is used for parameters in headers like @code{Content-Type} and
1053 @code{Content-Disposition}.
1055 @item mail-header-remove-comments
1056 @findex mail-header-remove-comments
1057 Return a comment-free version of a header.
1060 (mail-header-remove-comments
1061 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1062 @result{} "Gnus/5.070027 "
1065 @item mail-header-remove-whitespace
1066 @findex mail-header-remove-whitespace
1067 Remove linear white space from a header. Space inside quoted strings
1068 and comments is preserved.
1071 (mail-header-remove-whitespace
1072 "image/gif; name=\"Name with spaces\"")
1073 @result{} "image/gif;name=\"Name with spaces\""
1076 @item mail-header-get-comment
1077 @findex mail-header-get-comment
1078 Return the last comment in a header.
1081 (mail-header-get-comment
1082 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1083 @result{} "Finnish Landrace"
1086 @item mail-header-parse-address
1087 @findex mail-header-parse-address
1088 Parse an address and return a list containing the mailbox and the
1092 (mail-header-parse-address
1093 "Hrvoje Niksic <hniksic@@srce.hr>")
1094 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1097 @item mail-header-parse-addresses
1098 @findex mail-header-parse-addresses
1099 Parse a string with list of addresses and return a list of elements like
1100 the one described above.
1103 (mail-header-parse-addresses
1104 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1105 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1106 ("sb@@metis.no" . "Steinar Bang"))
1109 @item mail-header-parse-date
1110 @findex mail-header-parse-date
1111 Parse a date string and return an Emacs time structure.
1113 @item mail-narrow-to-head
1114 @findex mail-narrow-to-head
1115 Narrow the buffer to the header section of the buffer. Point is placed
1116 at the beginning of the narrowed buffer.
1118 @item mail-header-narrow-to-field
1119 @findex mail-header-narrow-to-field
1120 Narrow the buffer to the header under point. Understands continuation
1123 @item mail-header-fold-field
1124 @findex mail-header-fold-field
1125 Fold the header under point.
1127 @item mail-header-unfold-field
1128 @findex mail-header-unfold-field
1129 Unfold the header under point.
1131 @item mail-header-field-value
1132 @findex mail-header-field-value
1133 Return the value of the field under point.
1135 @item mail-encode-encoded-word-region
1136 @findex mail-encode-encoded-word-region
1137 Encode the non-@acronym{ASCII} words in the region. For instance,
1138 @samp{Naïve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1140 @item mail-encode-encoded-word-buffer
1141 @findex mail-encode-encoded-word-buffer
1142 Encode the non-@acronym{ASCII} words in the current buffer. This function is
1143 meant to be called narrowed to the headers of a message.
1145 @item mail-encode-encoded-word-string
1146 @findex mail-encode-encoded-word-string
1147 Encode the words that need encoding in a string, and return the result.
1150 (mail-encode-encoded-word-string
1151 "This is naïve, baby")
1152 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1155 @item mail-decode-encoded-word-region
1156 @findex mail-decode-encoded-word-region
1157 Decode the encoded words in the region.
1159 @item mail-decode-encoded-word-string
1160 @findex mail-decode-encoded-word-string
1161 Decode the encoded words in the string and return the result.
1164 (mail-decode-encoded-word-string
1165 "This is =?iso-8859-1?q?na=EFve,?= baby")
1166 @result{} "This is naïve, baby"
1171 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1172 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1173 in the subsequent sections.
1177 @node Basic Functions
1178 @chapter Basic Functions
1180 This chapter describes the basic, ground-level functions for parsing and
1181 handling. Covered here is parsing @code{From} lines, removing comments
1182 from header lines, decoding encoded words, parsing date headers and so
1183 on. High-level functionality is dealt with in the next chapter
1184 (@pxref{Decoding and Viewing}).
1187 * rfc2045:: Encoding @code{Content-Type} headers.
1188 * rfc2231:: Parsing @code{Content-Type} headers.
1189 * ietf-drums:: Handling mail headers defined by RFC822bis.
1190 * rfc2047:: En/decoding encoded words in headers.
1191 * time-date:: Functions for parsing dates and manipulating time.
1192 * qp:: Quoted-Printable en/decoding.
1193 * base64:: Base64 en/decoding.
1194 * binhex:: Binhex decoding.
1195 * uudecode:: Uuencode decoding.
1196 * yenc:: Yenc decoding.
1197 * rfc1843:: Decoding HZ-encoded text.
1198 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1205 RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would
1206 imagine that there would be a lot to implement. But there isn't, since
1207 most of the implementation details are delegated to the subsequent
1210 So @file{rfc2045.el} has only a single function:
1213 @item rfc2045-encode-string
1214 @findex rfc2045-encode-string
1215 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1216 @var{value} will be quoted if there are non-safe characters in it.
1223 RFC2231 defines a syntax for the @code{Content-Type} and
1224 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1225 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1228 In short, these headers look something like this:
1231 Content-Type: application/x-stuff;
1232 title*0*=us-ascii'en'This%20is%20even%20more%20;
1233 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1237 They usually aren't this bad, though.
1239 The following functions are defined by this library:
1242 @item rfc2231-parse-string
1243 @findex rfc2231-parse-string
1244 Parse a @code{Content-Type} header and return a list describing its
1248 (rfc2231-parse-string
1249 "application/x-stuff;
1250 title*0*=us-ascii'en'This%20is%20even%20more%20;
1251 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1252 title*2=\"isn't it!\"")
1253 @result{} ("application/x-stuff"
1254 (title . "This is even more ***fun*** isn't it!"))
1257 @item rfc2231-get-value
1258 @findex rfc2231-get-value
1259 Takes one of the lists on the format above and returns
1260 the value of the specified attribute.
1262 @item rfc2231-encode-string
1263 @findex rfc2231-encode-string
1264 Encode a parameter in headers likes @code{Content-Type} and
1265 @code{Content-Disposition}.
1273 @dfn{drums} is an IETF working group that is working on the replacement
1276 The functions provided by this library include:
1279 @item ietf-drums-remove-comments
1280 @findex ietf-drums-remove-comments
1281 Remove the comments from the argument and return the results.
1283 @item ietf-drums-remove-whitespace
1284 @findex ietf-drums-remove-whitespace
1285 Remove linear white space from the string and return the results.
1286 Spaces inside quoted strings and comments are left untouched.
1288 @item ietf-drums-get-comment
1289 @findex ietf-drums-get-comment
1290 Return the last most comment from the string.
1292 @item ietf-drums-parse-address
1293 @findex ietf-drums-parse-address
1294 Parse an address string and return a list that contains the mailbox and
1295 the plain text name.
1297 @item ietf-drums-parse-addresses
1298 @findex ietf-drums-parse-addresses
1299 Parse a string that contains any number of comma-separated addresses and
1300 return a list that contains mailbox/plain text pairs.
1302 @item ietf-drums-parse-date
1303 @findex ietf-drums-parse-date
1304 Parse a date string and return an Emacs time structure.
1306 @item ietf-drums-narrow-to-header
1307 @findex ietf-drums-narrow-to-header
1308 Narrow the buffer to the header section of the current buffer.
1316 RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how
1317 non-@acronym{ASCII} text in headers are to be encoded. This is actually rather
1318 complicated, so a number of variables are necessary to tweak what this
1321 The following variables are tweakable:
1324 @item rfc2047-default-charset
1325 @vindex rfc2047-default-charset
1326 Characters in this charset should not be decoded by this library.
1327 This defaults to @code{iso-8859-1}.
1329 @item rfc2047-header-encoding-alist
1330 @vindex rfc2047-header-encoding-alist
1331 This is an alist of header / encoding-type pairs. Its main purpose is
1332 to prevent encoding of certain headers.
1334 The keys can either be header regexps, or @code{t}.
1336 The values can be either @code{nil}, in which case the header(s) in
1337 question won't be encoded, or @code{mime}, which means that they will be
1340 @item rfc2047-charset-encoding-alist
1341 @vindex rfc2047-charset-encoding-alist
1342 RFC2047 specifies two forms of encoding---@code{Q} (a
1343 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1344 specifies which charset should use which encoding.
1346 @item rfc2047-encoding-function-alist
1347 @vindex rfc2047-encoding-function-alist
1348 This is an alist of encoding / function pairs. The encodings are
1349 @code{Q}, @code{B} and @code{nil}.
1351 @item rfc2047-q-encoding-alist
1352 @vindex rfc2047-q-encoding-alist
1353 The @code{Q} encoding isn't quite the same for all headers. Some
1354 headers allow a narrower range of characters, and that is what this
1355 variable is for. It's an alist of header regexps / allowable character
1358 @item rfc2047-encoded-word-regexp
1359 @vindex rfc2047-encoded-word-regexp
1360 When decoding words, this library looks for matches to this regexp.
1364 Those were the variables, and these are this functions:
1367 @item rfc2047-narrow-to-field
1368 @findex rfc2047-narrow-to-field
1369 Narrow the buffer to the header on the current line.
1371 @item rfc2047-encode-message-header
1372 @findex rfc2047-encode-message-header
1373 Should be called narrowed to the header of a message. Encodes according
1374 to @code{rfc2047-header-encoding-alist}.
1376 @item rfc2047-encode-region
1377 @findex rfc2047-encode-region
1378 Encodes all encodable words in the region specified.
1380 @item rfc2047-encode-string
1381 @findex rfc2047-encode-string
1382 Encode a string and return the results.
1384 @item rfc2047-decode-region
1385 @findex rfc2047-decode-region
1386 Decode the encoded words in the region.
1388 @item rfc2047-decode-string
1389 @findex rfc2047-decode-string
1390 Decode a string and return the results.
1398 While not really a part of the @acronym{MIME} library, it is convenient to
1399 document this library here. It deals with parsing @code{Date} headers
1400 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1403 These functions convert between five formats: A date string, an Emacs
1404 time structure, a decoded time list, a second number, and a day number.
1406 Here's a bunch of time/date/second/day examples:
1409 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1410 @result{} (54 21 12 12 9 1998 6 nil 7200)
1412 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1413 @result{} (13818 19266)
1415 (time-to-seconds '(13818 19266))
1416 @result{} 905595714.0
1418 (seconds-to-time 905595714.0)
1419 @result{} (13818 19266 0)
1421 (time-to-days '(13818 19266))
1424 (days-to-time 729644)
1425 @result{} (961933 65536)
1427 (time-since '(13818 19266))
1430 (time-less-p '(13818 19266) '(13818 19145))
1433 (subtract-time '(13818 19266) '(13818 19145))
1436 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1437 "Sat Sep 07 12:21:54 1998 +0200")
1440 (date-leap-year-p 2000)
1443 (time-to-day-in-year '(13818 19266))
1446 (time-to-number-of-days
1448 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1449 @result{} 4.146122685185185
1452 And finally, we have @code{safe-date-to-time}, which does the same as
1453 @code{date-to-time}, but returns a zero time if the date is
1454 syntactically malformed.
1456 The five data representations used are the following:
1460 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1461 12:21:54 1998 +0200"}.
1464 An internal Emacs time. For instance: @code{(13818 26466)}.
1467 A floating point representation of the internal Emacs time. For
1468 instance: @code{905595714.0}.
1471 An integer number representing the number of days since 00000101. For
1472 instance: @code{729644}.
1475 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1479 All the examples above represent the same moment.
1481 These are the functions available:
1485 Take a date and return a time.
1487 @item time-to-seconds
1488 Take a time and return seconds.
1490 @item seconds-to-time
1491 Take seconds and return a time.
1494 Take a time and return days.
1497 Take days and return a time.
1500 Take a date and return days.
1502 @item time-to-number-of-days
1503 Take a time and return the number of days that represents.
1505 @item safe-date-to-time
1506 Take a date and return a time. If the date is not syntactically valid,
1507 return a ``zero'' date.
1510 Take two times and say whether the first time is less (i. e., earlier)
1511 than the second time.
1514 Take a time and return a time saying how long it was since that time.
1517 Take two times and subtract the second from the first. I. e., return
1518 the time between the two times.
1521 Take two days and return the number of days between those two days.
1523 @item date-leap-year-p
1524 Take a year number and say whether it's a leap year.
1526 @item time-to-day-in-year
1527 Take a time and return the day number within the year that the time is
1536 This library deals with decoding and encoding Quoted-Printable text.
1538 Very briefly explained, qp encoding means translating all 8-bit
1539 characters (and lots of control characters) into things that look like
1540 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1543 The following functions are defined by the library:
1546 @item quoted-printable-decode-region
1547 @findex quoted-printable-decode-region
1548 QP-decode all the encoded text in the specified region.
1550 @item quoted-printable-decode-string
1551 @findex quoted-printable-decode-string
1552 Decode the QP-encoded text in a string and return the results.
1554 @item quoted-printable-encode-region
1555 @findex quoted-printable-encode-region
1556 QP-encode all the encodable characters in the specified region. The third
1557 optional parameter @var{fold} specifies whether to fold long lines.
1558 (Long here means 72.)
1560 @item quoted-printable-encode-string
1561 @findex quoted-printable-encode-string
1562 QP-encode all the encodable characters in a string and return the
1572 Base64 is an encoding that encodes three bytes into four characters,
1573 thereby increasing the size by about 33%. The alphabet used for
1574 encoding is very resistant to mangling during transit.
1576 The following functions are defined by this library:
1579 @item base64-encode-region
1580 @findex base64-encode-region
1581 base64 encode the selected region. Return the length of the encoded
1582 text. Optional third argument @var{no-line-break} means do not break
1583 long lines into shorter lines.
1585 @item base64-encode-string
1586 @findex base64-encode-string
1587 base64 encode a string and return the result.
1589 @item base64-decode-region
1590 @findex base64-decode-region
1591 base64 decode the selected region. Return the length of the decoded
1592 text. If the region can't be decoded, return @code{nil} and don't
1595 @item base64-decode-string
1596 @findex base64-decode-string
1597 base64 decode a string and return the result. If the string can't be
1598 decoded, @code{nil} is returned.
1609 @code{binhex} is an encoding that originated in Macintosh environments.
1610 The following function is supplied to deal with these:
1613 @item binhex-decode-region
1614 @findex binhex-decode-region
1615 Decode the encoded text in the region. If given a third parameter, only
1616 decode the @code{binhex} header and return the filename.
1625 @code{uuencode} is probably still the most popular encoding of binaries
1626 used on Usenet, although @code{base64} rules the mail world.
1628 The following function is supplied by this package:
1631 @item uudecode-decode-region
1632 @findex uudecode-decode-region
1633 Decode the text in the region.
1641 @code{yenc} is used for encoding binaries on Usenet. The following
1642 function is supplied by this package:
1645 @item yenc-decode-region
1646 @findex yenc-decode-region
1647 Decode the encoded text in the region.
1658 RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In
1659 essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this:
1662 This sentence is in @acronym{ASCII}.
1663 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1666 Simple enough, and widely used in China.
1668 The following functions are available to handle this encoding:
1671 @item rfc1843-decode-region
1672 Decode HZ-encoded text in the region.
1674 @item rfc1843-decode-string
1675 Decode a HZ-encoded string and return the result.
1683 The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message
1684 handlers and describes how elements are supposed to be displayed.
1685 Here's an example file:
1689 audio/wav; wavplayer %s
1690 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1693 This says that all image files should be displayed with @code{gimp},
1694 that WAVE audio files should be played by @code{wavplayer}, and that
1695 MS-WORD files should be inlined by @code{catdoc}.
1697 The @code{mailcap} library parses this file, and provides functions for
1701 @item mailcap-mime-data
1702 @vindex mailcap-mime-data
1703 This variable is an alist of alists containing backup viewing rules.
1707 Interface functions:
1710 @item mailcap-parse-mailcaps
1711 @findex mailcap-parse-mailcaps
1712 Parse the @file{~/.mailcap} file.
1714 @item mailcap-mime-info
1715 Takes a @acronym{MIME} type as its argument and returns the matching viewer.
1725 The Emacs @acronym{MIME} library implements handling of various elements
1726 according to a (somewhat) large number of RFCs, drafts and standards
1727 documents. This chapter lists the relevant ones. They can all be
1728 fetched from @uref{http://quimby.gnus.org/notes/}.
1733 Standard for the Format of ARPA Internet Text Messages.
1736 Standard for Interchange of USENET Messages
1739 Format of Internet Message Bodies
1745 Message Header Extensions for Non-@acronym{ASCII} Text
1748 Registration Procedures
1751 Conformance Criteria and Examples
1754 @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets,
1755 Languages, and Continuations
1758 HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1759 @acronym{ASCII} characters
1761 @item draft-ietf-drums-msg-fmt-05.txt
1762 Draft for the successor of RFC822
1765 The @acronym{MIME} Multipart/Related Content-type
1768 The Multipart/Report Content Type for the Reporting of Mail System
1769 Administrative Messages
1772 Communicating Presentation Information in Internet Messages: The
1773 Content-Disposition Header Field
1776 Documentation of the text/plain format parameter for flowed text.
1792 @c coding: iso-8859-1