3 @include gnus-overrides.texi
5 @setfilename ../../info/emacs-mime.info
6 @settitle Emacs MIME Manual
13 This file documents the Emacs MIME interface functionality.
15 Copyright @copyright{} 1998--2016 Free Software Foundation, Inc.
18 Permission is granted to copy, distribute and/or modify this document
19 under the terms of the GNU Free Documentation License, Version 1.3 or
20 any later version published by the Free Software Foundation; with no
21 Invariant Sections, with the Front-Cover Texts being ``A GNU Manual'',
22 and with the Back-Cover Texts as in (a) below. A copy of the license
23 is included in the section entitled ``GNU Free Documentation License''.
25 (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
26 modify this GNU manual.''
30 @c Node ``Interface Functions'' uses non-ASCII characters
32 @dircategory Emacs lisp libraries
34 * Emacs MIME: (emacs-mime). Emacs MIME de/composition library.
39 @setchapternewpage odd
43 @title Emacs MIME Manual (DEVELOPMENT VERSION)
46 @title Emacs MIME Manual
49 @author by Lars Magne Ingebrigtsen
51 @vskip 0pt plus 1filll
60 This manual documents the libraries used to compose and display
61 @acronym{MIME} messages.
63 This manual is directed at users who want to modify the behavior of
64 the @acronym{MIME} encoding/decoding process or want a more detailed
65 picture of how the Emacs @acronym{MIME} library works, and people who want
66 to write functions and commands that manipulate @acronym{MIME} elements.
68 @acronym{MIME} is short for @dfn{Multipurpose Internet Mail Extensions}.
69 This standard is documented in a number of RFCs; mainly RFC2045 (Format
70 of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message
71 Header Extensions for Non-@acronym{ASCII} Text), RFC2048 (Registration
72 Procedures), RFC2049 (Conformance Criteria and Examples). It is highly
73 recommended that anyone who intends writing @acronym{MIME}-compliant software
74 read at least RFC2045 and RFC2047.
81 * Decoding and Viewing:: A framework for decoding and viewing.
82 * Composing:: @acronym{MML}; a language for describing @acronym{MIME} parts.
83 * Interface Functions:: An abstraction over the basic functions.
84 * Basic Functions:: Utility and basic parsing functions.
85 * Standards:: A summary of RFCs and working documents used.
86 * GNU Free Documentation License:: The license for this documentation.
87 * Index:: Function and variable index.
91 @node Decoding and Viewing
92 @chapter Decoding and Viewing
94 This chapter deals with decoding and viewing @acronym{MIME} messages on a
97 The main idea is to first analyze a @acronym{MIME} article, and then allow
98 other programs to do things based on the list of @dfn{handles} that are
99 returned as a result of this analysis.
102 * Dissection:: Analyzing a @acronym{MIME} message.
103 * Non-MIME:: Analyzing a non-@acronym{MIME} message.
104 * Handles:: Handle manipulations.
105 * Display:: Displaying handles.
106 * Display Customization:: Variables that affect display.
107 * Files and Directories:: Saving and naming attachments.
108 * New Viewers:: How to write your own viewers.
115 The @code{mm-dissect-buffer} is the function responsible for dissecting
116 a @acronym{MIME} article. If given a multipart message, it will recursively
117 descend the message, following the structure, and return a tree of
118 @acronym{MIME} handles that describes the structure of the message.
122 @vindex mm-uu-configure-list
124 Gnus also understands some non-@acronym{MIME} attachments, such as
125 postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp,
126 diff. Each of these features can be disabled by add an item into
127 @code{mm-uu-configure-list}. For example,
131 (add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
157 Non-@acronym{MIME} forwarded message.
165 @acronym{PGP} signed clear text.
168 @findex pgp-encrypted
169 @acronym{PGP} encrypted clear text.
173 @acronym{PGP} public keys.
176 @findex emacs-sources
177 @vindex mm-uu-emacs-sources-regexp
178 Emacs source code. This item works only in the groups matching
179 @code{mm-uu-emacs-sources-regexp}.
183 @vindex mm-uu-diff-groups-regexp
184 Patches. This is intended for groups where diffs of committed files
185 are automatically sent to. It only works in groups matching
186 @code{mm-uu-diff-groups-regexp}.
189 @cindex verbatim-marks
190 Slrn-style verbatim marks.
194 LaTeX documents. It only works in groups matching
195 @code{mm-uu-tex-groups-regexp}.
199 @cindex text/x-verbatim
200 @c Is @vindex suitable for a face?
201 @vindex mm-uu-extract
202 Some inlined non-@acronym{MIME} attachments are displayed using the face
203 @code{mm-uu-extract}. By default, no @acronym{MIME} button for these
204 parts is displayed. You can force displaying a button using @kbd{K b}
205 (@code{gnus-summary-display-buttonized}) or add @code{text/x-verbatim}
206 to @code{gnus-buttonized-mime-types}, @xref{MIME Commands, ,MIME
207 Commands, gnus, Gnus Manual}.
212 A @acronym{MIME} handle is a list that fully describes a @acronym{MIME}
215 The following macros can be used to access elements in a handle:
218 @item mm-handle-buffer
219 @findex mm-handle-buffer
220 Return the buffer that holds the contents of the undecoded @acronym{MIME}
224 @findex mm-handle-type
225 Return the parsed @code{Content-Type} of the part.
227 @item mm-handle-encoding
228 @findex mm-handle-encoding
229 Return the @code{Content-Transfer-Encoding} of the part.
231 @item mm-handle-undisplayer
232 @findex mm-handle-undisplayer
233 Return the object that can be used to remove the displayed part (if it
236 @item mm-handle-set-undisplayer
237 @findex mm-handle-set-undisplayer
238 Set the undisplayer object.
240 @item mm-handle-disposition
241 @findex mm-handle-disposition
242 Return the parsed @code{Content-Disposition} of the part.
244 @item mm-get-content-id
245 Returns the handle(s) referred to by @code{Content-ID}.
253 Functions for displaying, removing and saving.
256 @item mm-display-part
257 @findex mm-display-part
261 @findex mm-remove-part
262 Remove the part (if it has been displayed).
265 @findex mm-inlinable-p
266 Say whether a @acronym{MIME} type can be displayed inline.
268 @item mm-automatic-display-p
269 @findex mm-automatic-display-p
270 Say whether a @acronym{MIME} type should be displayed automatically.
272 @item mm-destroy-part
273 @findex mm-destroy-part
274 Free all resources occupied by a part.
278 Offer to save the part in a file.
282 Offer to pipe the part to some process.
284 @item mm-interactively-view-part
285 @findex mm-interactively-view-part
286 Prompt for a mailcap method to use to view the part.
291 @node Display Customization
292 @section Display Customization
296 @item mm-inline-media-tests
297 @vindex mm-inline-media-tests
298 This is an alist where the key is a @acronym{MIME} type, the second element
299 is a function to display the part @dfn{inline} (i.e., inside Emacs), and
300 the third element is a form to be @code{eval}ed to say whether the part
301 can be displayed inline.
303 This variable specifies whether a part @emph{can} be displayed inline,
304 and, if so, how to do it. It does not say whether parts are
305 @emph{actually} displayed inline.
307 @item mm-inlined-types
308 @vindex mm-inlined-types
309 This, on the other hand, says what types are to be displayed inline, if
310 they satisfy the conditions set by the variable above. It's a list of
311 @acronym{MIME} media types.
313 @item mm-automatic-display
314 @vindex mm-automatic-display
315 This is a list of types that are to be displayed ``automatically'', but
316 only if the above variable allows it. That is, only inlinable parts can
317 be displayed automatically.
319 @item mm-automatic-external-display
320 @vindex mm-automatic-external-display
321 This is a list of types that will be displayed automatically in an
324 @item mm-keep-viewer-alive-types
325 @vindex mm-keep-viewer-alive-types
326 This is a list of media types for which the external viewer will not
327 be killed when selecting a different article.
329 @item mm-attachment-override-types
330 @vindex mm-attachment-override-types
331 Some @acronym{MIME} agents create parts that have a content-disposition of
332 @samp{attachment}. This variable allows overriding that disposition and
333 displaying the part inline. (Note that the disposition is only
334 overridden if we are able to, and want to, display the part inline.)
336 @item mm-discouraged-alternatives
337 @vindex mm-discouraged-alternatives
338 List of @acronym{MIME} types that are discouraged when viewing
339 @samp{multipart/alternative}. Viewing agents are supposed to view the
340 last possible part of a message, as that is supposed to be the richest.
341 However, users may prefer other types instead, and this list says what
342 types are most unwanted. If, for instance, @samp{text/html} parts are
343 very unwanted, and @samp{text/richtext} parts are somewhat unwanted,
344 you could say something like:
347 (setq mm-discouraged-alternatives
348 '("text/html" "text/richtext")
350 (remove "text/html" mm-automatic-display))
353 Adding @code{"image/.*"} might also be useful. Spammers use images as
354 the preferred part of @samp{multipart/alternative} messages, so you might
355 not notice there are other parts. See also
356 @code{gnus-buttonized-mime-types}, @ref{MIME Commands, ,MIME Commands,
357 gnus, Gnus Manual}. After adding @code{"multipart/alternative"} to
358 @code{gnus-buttonized-mime-types} you can choose manually which
359 alternative you'd like to view. For example, you can set those
363 (setq gnus-buttonized-mime-types
364 '("multipart/alternative" "multipart/signed")
365 mm-discouraged-alternatives
366 '("text/html" "image/.*"))
369 In this case, Gnus will display radio buttons for such a kind of spam
373 1. (*) multipart/alternative ( ) image/gif
375 2. (*) text/plain ( ) text/html
378 @item mm-inline-large-images
379 @vindex mm-inline-large-images
380 When displaying inline images that are larger than the window, Emacs
381 does not enable scrolling, which means that you cannot see the whole
382 image. To prevent this, the library tries to determine the image size
383 before displaying it inline, and if it doesn't fit the window, the
384 library will display it externally (e.g., with @samp{ImageMagick} or
385 @samp{xv}). Setting this variable to @code{t} disables this check and
386 makes the library display all inline images as inline, regardless of
387 their size. If you set this variable to @code{resize}, the image will
388 be displayed resized to fit in the window, if Emacs has the ability to
391 @item mm-inline-large-images-proportion
392 @vindex mm-inline-images-max-proportion
393 The proportion used when resizing large images.
395 @item mm-inline-override-types
396 @vindex mm-inline-override-types
397 @code{mm-inlined-types} may include regular expressions, for example to
398 specify that all @samp{text/.*} parts be displayed inline. If a user
399 prefers to have a type that matches such a regular expression be treated
400 as an attachment, that can be accomplished by setting this variable to a
401 list containing that type. For example assuming @code{mm-inlined-types}
402 includes @samp{text/.*}, then including @samp{text/html} in this
403 variable will cause @samp{text/html} parts to be treated as attachments.
405 @item mm-text-html-renderer
406 @vindex mm-text-html-renderer
407 This selects the function used to render @acronym{HTML}. The predefined
408 renderers are selected by the symbols @code{gnus-article-html},
409 @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
410 information about emacs-w3m}, @code{links}, @code{lynx},
411 @code{w3m-standalone} or @code{html2text}. If @code{nil} use an
412 external viewer. You can also specify a function, which will be
413 called with a @acronym{MIME} handle as the argument.
415 @item mm-html-inhibit-images
416 @vindex mm-html-inhibit-images
417 @vindex mm-inline-text-html-with-images
418 If this is non-@code{nil}, inhibit displaying of images inline in the
419 article body. It is effective to images in @acronym{HTML} articles
420 rendered when @code{mm-text-html-renderer} (@pxref{Display
421 Customization}) is @code{shr} or @code{w3m}. In Gnus, this is
422 overridden by the value of @code{gnus-inhibit-images} (@pxref{Misc
423 Article, ,Misc Article, gnus, Gnus manual}).
425 @item mm-html-blocked-images
426 @vindex mm-html-blocked-images
427 External images that have @acronym{URL}s that match this regexp won't
428 be fetched and displayed. For instance, do block all @acronym{URL}s
429 that have the string ``ads'' in them, do the following:
432 (setq mm-html-blocked-images "ads")
435 It is effective when @code{mm-text-html-renderer} (@pxref{Display
436 Customization}) is @code{shr}. In Gnus, this is overridden by the value
437 of @code{gnus-blocked-images} or the return value of the function that
438 @code{gnus-blocked-images} is set to (@pxref{HTML, ,HTML, gnus, Gnus
441 @item mm-w3m-safe-url-regexp
442 @vindex mm-w3m-safe-url-regexp
443 A regular expression that matches safe URL names, i.e., URLs that are
444 unlikely to leak personal information when rendering @acronym{HTML}
445 email (the default value is @samp{\\`cid:}). If @code{nil} consider
446 all URLs safe. In Gnus, this will be overridden according to the value
447 of the variable @code{gnus-safe-html-newsgroups}, @xref{Various
448 Various, ,Various Various, gnus, Gnus Manual}.
450 @item mm-inline-text-html-with-w3m-keymap
451 @vindex mm-inline-text-html-with-w3m-keymap
452 You can use emacs-w3m command keys in the inlined text/html part by
453 setting this option to non-@code{nil}. The default value is @code{t}.
455 @item mm-external-terminal-program
456 @vindex mm-external-terminal-program
457 The program used to start an external terminal.
459 @item mm-enable-external
460 @vindex mm-enable-external
461 Indicate whether external @acronym{MIME} handlers should be used.
463 If @code{t}, all defined external @acronym{MIME} handlers are used. If
464 @code{nil}, files are saved to disk (@code{mailcap-save-binary-file}).
465 If it is the symbol @code{ask}, you are prompted before the external
466 @acronym{MIME} handler is invoked.
468 When you launch an attachment through mailcap (@pxref{mailcap}) an
469 attempt is made to use a safe viewer with the safest options---this isn't
470 the case if you save it to disk and launch it in a different way
471 (command line or double-clicking). Anyhow, if you want to be sure not
472 to launch any external programs, set this variable to @code{nil} or
477 @node Files and Directories
478 @section Files and Directories
482 @item mm-default-directory
483 @vindex mm-default-directory
484 The default directory for saving attachments. If @code{nil} use
485 @code{default-directory}.
487 @item mm-tmp-directory
488 @vindex mm-tmp-directory
489 Directory for storing temporary files.
491 @item mm-file-name-rewrite-functions
492 @vindex mm-file-name-rewrite-functions
493 A list of functions used for rewriting file names of @acronym{MIME}
494 parts. Each function is applied successively to the file name.
495 Ready-made functions include
498 @item mm-file-name-delete-control
499 @findex mm-file-name-delete-control
500 Delete all control characters.
502 @item mm-file-name-delete-gotchas
503 @findex mm-file-name-delete-gotchas
504 Delete characters that could have unintended consequences when used
505 with flawed shell scripts, i.e., @samp{|}, @samp{>} and @samp{<}; and
506 @samp{-}, @samp{.} as the first character.
508 @item mm-file-name-delete-whitespace
509 @findex mm-file-name-delete-whitespace
510 Remove all whitespace.
512 @item mm-file-name-trim-whitespace
513 @findex mm-file-name-trim-whitespace
514 Remove leading and trailing whitespace.
516 @item mm-file-name-collapse-whitespace
517 @findex mm-file-name-collapse-whitespace
518 Collapse multiple whitespace characters.
520 @item mm-file-name-replace-whitespace
521 @findex mm-file-name-replace-whitespace
522 @vindex mm-file-name-replace-whitespace
523 Replace whitespace with underscores. Set the variable
524 @code{mm-file-name-replace-whitespace} to any other string if you do
525 not like underscores.
528 The standard Emacs functions @code{capitalize}, @code{downcase},
529 @code{upcase} and @code{upcase-initials} might also prove useful.
531 @item mm-path-name-rewrite-functions
532 @vindex mm-path-name-rewrite-functions
533 List of functions used for rewriting the full file names of @acronym{MIME}
534 parts. This is used when viewing parts externally, and is meant for
535 transforming the absolute name so that non-compliant programs can find
536 the file where it's saved.
543 Here's an example viewer for displaying @code{text/enriched} inline:
546 (defun mm-display-enriched-inline (handle)
549 (mm-insert-part handle)
550 (save-window-excursion
551 (enriched-decode (point-min) (point-max))
552 (setq text (buffer-string))))
553 (mm-insert-inline handle text)))
556 We see that the function takes a @acronym{MIME} handle as its parameter. It
557 then goes to a temporary buffer, inserts the text of the part, does some
558 work on the text, stores the result, goes back to the buffer it was
559 called from and inserts the result.
561 The two important helper functions here are @code{mm-insert-part} and
562 @code{mm-insert-inline}. The first function inserts the text of the
563 handle in the current buffer. It handles charset and/or content
564 transfer decoding. The second function just inserts whatever text you
565 tell it to insert, but it also sets things up so that the text can be
566 ``undisplayed'' in a convenient manner.
572 @cindex MIME Composing
574 @cindex MIME Meta Language
576 Creating a @acronym{MIME} message is boring and non-trivial. Therefore,
577 a library called @code{mml} has been defined that parses a language
578 called @acronym{MML} (@acronym{MIME} Meta Language) and generates
579 @acronym{MIME} messages.
581 @findex mml-generate-mime
582 The main interface function is @code{mml-generate-mime}. It will
583 examine the contents of the current (narrowed-to) buffer and return a
584 string containing the @acronym{MIME} message.
587 * Simple MML Example:: An example @acronym{MML} document.
588 * MML Definition:: All valid @acronym{MML} elements.
589 * Advanced MML Example:: Another example @acronym{MML} document.
590 * Encoding Customization:: Variables that affect encoding.
591 * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}.
592 * Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa.
593 * Flowed text:: Soft and hard newlines.
597 @node Simple MML Example
598 @section Simple MML Example
600 Here's a simple @samp{multipart/alternative}:
603 <#multipart type=alternative>
604 This is a plain text part.
605 <#part type=text/enriched>
606 <center>This is a centered enriched part</center>
610 After running this through @code{mml-generate-mime}, we get this:
613 Content-Type: multipart/alternative; boundary="=-=-="
619 This is a plain text part.
622 Content-Type: text/enriched
625 <center>This is a centered enriched part</center>
632 @section MML Definition
634 The @acronym{MML} language is very simple. It looks a bit like an SGML
635 application, but it's not.
637 The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a
638 different type or use a different charset. The way to delineate a part
639 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
640 with the @samp{<#multipart ...>} tag. Parts are ended by the
641 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
642 @samp{<#part ...>} tags are also closed by the next open tag.
644 There's also the @samp{<#external ...>} tag. These introduce
645 @samp{external/message-body} parts.
647 Each tag can contain zero or more parameters on the form
648 @samp{parameter=value}. The values may be enclosed in quotation marks,
649 but that's not necessary unless the value contains white space. So
650 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
652 The following parameters have meaning in @acronym{MML}; parameters that have no
653 meaning are ignored. The @acronym{MML} parameter names are the same as the
654 @acronym{MIME} parameter names; the things in the parentheses say which
655 header it will be used in.
659 The @acronym{MIME} type of the part (@code{Content-Type}).
662 Use the contents of the file in the body of the part
663 (@code{Content-Disposition}).
665 @item recipient-filename
666 Use this as the file name in the generated @acronym{MIME} message for
667 the recipient. That is, even if the file is called @file{foo.txt}
668 locally, use this name instead in the @code{Content-Disposition} in
672 The contents of the body of the part are to be encoded in the character
673 set specified (@code{Content-Type}). @xref{Charset Translation}.
676 Might be used to suggest a file name if the part is to be saved
677 to a file (@code{Content-Type}).
680 Valid values are @samp{inline} and @samp{attachment}
681 (@code{Content-Disposition}).
684 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
685 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
689 A description of the part (@code{Content-Description}).
692 RFC822 date when the part was created (@code{Content-Disposition}).
694 @item modification-date
695 RFC822 date when the part was modified (@code{Content-Disposition}).
698 RFC822 date when the part was read (@code{Content-Disposition}).
701 Who to encrypt/sign the part to. This field is used to override any
702 auto-detection based on the To/CC headers.
705 Identity used to sign the part. This field is used to override the
709 The size (in octets) of the part (@code{Content-Disposition}).
712 What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp}
716 What technology to encrypt this @acronym{MML} part with (@code{smime},
717 @code{pgp} or @code{pgpmime})
721 Parameters for @samp{text/plain}:
725 Formatting parameter for the text, valid values include @samp{fixed}
726 (the default) and @samp{flowed}. Normally you do not specify this
727 manually, since it requires the textual body to be formatted in a
728 special way described in RFC 2646. @xref{Flowed text}.
731 Parameters for @samp{application/octet-stream}:
735 Type of the part; informal---meant for human readers
736 (@code{Content-Type}).
739 Parameters for @samp{message/external-body}:
743 A word indicating the supported access mechanism by which the file may
744 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
745 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
748 The RFC822 date after which the file may no longer be fetched.
749 (@code{Content-Type}.)
752 The size (in octets) of the file. (@code{Content-Type}.)
755 Valid values are @samp{read} and @samp{read-write}
756 (@code{Content-Type}).
760 Parameters for @samp{sign=smime}:
765 File containing key and certificate for signer.
769 Parameters for @samp{encrypt=smime}:
774 File containing certificate for recipient.
779 @node Advanced MML Example
780 @section Advanced MML Example
782 Here's a complex multipart message. It's a @samp{multipart/mixed} that
783 contains many parts, one of which is a @samp{multipart/alternative}.
786 <#multipart type=mixed>
787 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
788 <#multipart type=alternative>
789 This is a plain text part.
790 <#part type=text/enriched name=enriched.txt>
791 <center>This is a centered enriched part</center>
793 This is a new plain text part.
794 <#part disposition=attachment>
795 This plain text part is an attachment.
799 And this is the resulting @acronym{MIME} message:
802 Content-Type: multipart/mixed; boundary="=-=-="
810 Content-Type: image/jpeg;
812 Content-Disposition: inline;
814 Content-Transfer-Encoding: base64
816 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
817 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
818 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
819 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
820 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
821 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
822 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
823 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
824 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
825 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
826 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
827 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
828 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
829 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
830 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
831 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
832 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
835 Content-Type: multipart/alternative; boundary="==-=-="
841 This is a plain text part.
844 Content-Type: text/enriched;
848 <center>This is a centered enriched part</center>
854 This is a new plain text part.
857 Content-Disposition: attachment
860 This plain text part is an attachment.
865 @node Encoding Customization
866 @section Encoding Customization
870 @item mm-body-charset-encoding-alist
871 @vindex mm-body-charset-encoding-alist
872 Mapping from @acronym{MIME} charset to encoding to use. This variable is
873 usually used except, e.g., when other requirements force a specific
874 encoding (digitally signed messages require 7bit encodings). The
878 ((iso-2022-jp . 7bit)
879 (iso-2022-jp-2 . 7bit)
885 As an example, if you do not want to have ISO-8859-1 characters
886 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
887 this variable. You can override this setting on a per-message basis
888 by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
890 @item mm-coding-system-priorities
891 @vindex mm-coding-system-priorities
892 Prioritize coding systems to use for outgoing messages. The default
893 is @code{nil}, which means to use the defaults in Emacs, but is
894 @code{(iso-8859-1 iso-2022-jp utf-8)} when running Emacs in the Japanese
895 language environment. It is a list of coding system symbols (aliases of
896 coding systems are also allowed, use @kbd{M-x describe-coding-system} to
897 make sure you are specifying correct coding system names). For example,
898 if you have configured Emacs to prefer UTF-8, but wish that outgoing
899 messages should be sent in ISO-8859-1 if possible, you can set this
900 variable to @code{(iso-8859-1)}. You can override this setting on a
901 per-message basis by using the @code{charset} @acronym{MML} tag
902 (@pxref{MML Definition}).
904 As different hierarchies prefer different charsets, you may want to set
905 @code{mm-coding-system-priorities} according to the hierarchy in Gnus.
908 @c Corrections about preferred charsets are welcome. de, fr and fj
909 @c should be correct, I don't know about the rest (so these are only
912 (add-to-list 'gnus-newsgroup-variables 'mm-coding-system-priorities)
913 (setq gnus-parameters
915 ;; Some charsets are just examples!
916 '(("^cn\\." ;; Chinese
917 (mm-coding-system-priorities
918 '(iso-8859-1 cn-big5 chinese-iso-7bit utf-8)))
919 ("^cz\\.\\|^pl\\." ;; Central and Eastern European
920 (mm-coding-system-priorities '(iso-8859-2 utf-8)))
921 ("^de\\." ;; German language
922 (mm-coding-system-priorities '(iso-8859-1 iso-8859-15 utf-8)))
924 (mm-coding-system-priorities '(iso-8859-15 iso-8859-1 utf-8)))
925 ("^fj\\." ;; Japanese
926 (mm-coding-system-priorities
927 '(iso-8859-1 iso-2022-jp utf-8)))
928 ("^ru\\." ;; Cyrillic
929 (mm-coding-system-priorities
930 '(koi8-r iso-8859-5 iso-8859-1 utf-8))))
934 @item mm-content-transfer-encoding-defaults
935 @vindex mm-content-transfer-encoding-defaults
936 Mapping from @acronym{MIME} types to encoding to use. This variable is usually
937 used except, e.g., when other requirements force a safer encoding
938 (digitally signed messages require 7bit encoding). Besides the normal
939 @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
940 each case the most efficient of quoted-printable and base64 should be
943 @code{qp-or-base64} has another effect. It will fold long lines so that
944 MIME parts may not be broken by MTA@. So do @code{quoted-printable} and
947 Note that it affects body encoding only when a part is a raw forwarded
948 message (which will be made by @code{gnus-summary-mail-forward} with the
949 arg 2 for example) or is neither the @samp{text/*} type nor the
950 @samp{message/*} type. Even though in those cases, you can override
951 this setting on a per-message basis by using the @code{encoding}
952 @acronym{MML} tag (@pxref{MML Definition}).
954 @item mm-use-ultra-safe-encoding
955 @vindex mm-use-ultra-safe-encoding
956 When this is non-@code{nil}, it means that textual parts are encoded as
957 quoted-printable if they contain lines longer than 76 characters or
958 starting with "From " in the body. Non-7bit encodings (8bit, binary)
959 are generally disallowed. This reduce the probability that a non-8bit
960 clean MTA or MDA changes the message. This should never be set
961 directly, but bound by other functions when necessary (e.g., when
962 encoding messages that are to be digitally signed).
966 @node Charset Translation
967 @section Charset Translation
970 During translation from @acronym{MML} to @acronym{MIME}, for each
971 @acronym{MIME} part which has been composed inside Emacs, an appropriate
972 charset has to be chosen.
974 @vindex mail-parse-charset
975 If you are running a non-@sc{mule} Emacs, this process is simple: If the
976 part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset
977 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
978 variable directly, though. If you want to change the default charset,
979 please consult the documentation of the package which you use to process
980 @acronym{MIME} messages.
981 @xref{Various Message Variables, , Various Message Variables, message,
982 Message Manual}, for example.)
983 If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is
989 @vindex mm-mime-mule-charset-alist
990 Things are slightly more complicated when running Emacs with @sc{mule}
991 support. In this case, a list of the @sc{mule} charsets used in the
992 part is obtained, and the @sc{mule} charsets are translated to
993 @acronym{MIME} charsets by consulting the table provided by Emacs itself
994 or the variable @code{mm-mime-mule-charset-alist} for XEmacs.
995 If this results in a single @acronym{MIME} charset, this is used to encode
996 the part. But if the resulting list of @acronym{MIME} charsets contains more
997 than one element, two things can happen: If it is possible to encode the
998 part via UTF-8, this charset is used. (For this, Emacs must support
999 the @code{utf-8} coding system, and the part must consist entirely of
1000 characters which have Unicode counterparts.) If UTF-8 is not available
1001 for some reason, the part is split into several ones, so that each one
1002 can be encoded with a single @acronym{MIME} charset. The part can only be
1003 split at line boundaries, though---if more than one @acronym{MIME} charset is
1004 required to encode a single line, it is not possible to encode the part.
1006 When running Emacs with @sc{mule} support, the preferences for which
1007 coding system to use is inherited from Emacs itself. This means that
1008 if Emacs is set up to prefer UTF-8, it will be used when encoding
1009 messages. You can modify this by altering the
1010 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
1013 The charset to be used can be overridden by setting the @code{charset}
1014 @acronym{MML} tag (@pxref{MML Definition}) when composing the message.
1016 The encoding of characters (quoted-printable, 8bit, etc.)@: is orthogonal
1017 to the discussion here, and is controlled by the variables
1018 @code{mm-body-charset-encoding-alist} and
1019 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
1026 A (multipart) @acronym{MIME} message can be converted to @acronym{MML}
1027 with the @code{mime-to-mml} function. It works on the message in the
1028 current buffer, and substitutes @acronym{MML} markup for @acronym{MIME}
1029 boundaries. Non-textual parts do not have their contents in the buffer,
1030 but instead have the contents in separate buffers that are referred to
1031 from the @acronym{MML} tags.
1034 An @acronym{MML} message can be converted back to @acronym{MIME} by the
1035 @code{mml-to-mime} function.
1037 These functions are in certain senses ``lossy''---you will not get back
1038 an identical message if you run @code{mime-to-mml} and then
1039 @code{mml-to-mime}. Not only will trivial things like the order of the
1040 headers differ, but the contents of the headers may also be different.
1041 For instance, the original message may use base64 encoding on text,
1042 while @code{mml-to-mime} may decide to use quoted-printable encoding, and
1045 In essence, however, these two functions should be the inverse of each
1046 other. The resulting contents of the message should remain equivalent,
1051 @section Flowed text
1052 @cindex format=flowed
1054 The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines}
1055 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
1056 emacs, Emacs Manual}) when encoding a message, and the
1057 ``format=flowed'' Content-Type parameter when decoding a message.
1059 On encoding text, regardless of @code{use-hard-newlines}, lines
1060 terminated by soft newline characters are filled together and wrapped
1061 after the column decided by @code{fill-flowed-encode-column}.
1062 Quotation marks (matching @samp{^>* ?}) are respected. The variable
1063 controls how the text will look in a client that does not support
1064 flowed text, the default is to wrap after 66 characters. If hard
1065 newline characters are not present in the buffer, no flow encoding
1068 You can customize the value of the @code{mml-enable-flowed} variable
1069 to enable or disable the flowed encoding usage when newline
1070 characters are present in the buffer.
1072 On decoding flowed text, lines with soft newline characters are filled
1073 together and wrapped after the column decided by
1074 @code{fill-flowed-display-column}. The default is to wrap after
1078 @item mm-fill-flowed
1079 @vindex mm-fill-flowed
1080 If non-@code{nil} a format=flowed article will be displayed flowed.
1084 @node Interface Functions
1085 @chapter Interface Functions
1086 @cindex interface functions
1089 The @code{mail-parse} library is an abstraction over the actual
1090 low-level libraries that are described in the next chapter.
1092 Standards change, and so programs have to change to fit in the new
1093 mold. For instance, RFC2045 describes a syntax for the
1094 @code{Content-Type} header that only allows @acronym{ASCII} characters in the
1095 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
1096 for continuation headers and non-@acronym{ASCII} characters.
1098 The traditional way to deal with this is just to update the library
1099 functions to parse the new syntax. However, this is sometimes the wrong
1100 thing to do. In some instances it may be vital to be able to understand
1101 both the old syntax as well as the new syntax, and if there is only one
1102 library, one must choose between the old version of the library and the
1103 new version of the library.
1105 The Emacs @acronym{MIME} library takes a different tack. It defines a
1106 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
1107 and so on) that parses strictly according to the corresponding
1108 standard. However, normal programs would not use the functions
1109 provided by these libraries directly, but instead use the functions
1110 provided by the @code{mail-parse} library. The functions in this
1111 library are just aliases to the corresponding functions in the latest
1112 low-level libraries. Using this scheme, programs get a consistent
1113 interface they can use, and library developers are free to create
1114 write code that handles new standards.
1116 The following functions are defined by this library:
1119 @item mail-header-parse-content-type
1120 @findex mail-header-parse-content-type
1121 Parse a @code{Content-Type} header and return a list on the following
1126 (attribute1 . value1)
1127 (attribute2 . value2)
1134 (mail-header-parse-content-type
1135 "image/gif; name=\"b980912.gif\"")
1136 @result{} ("image/gif" (name . "b980912.gif"))
1139 @item mail-header-parse-content-disposition
1140 @findex mail-header-parse-content-disposition
1141 Parse a @code{Content-Disposition} header and return a list on the same
1142 format as the function above.
1144 @item mail-content-type-get
1145 @findex mail-content-type-get
1146 Takes two parameters---a list on the format above, and an attribute.
1147 Returns the value of the attribute.
1150 (mail-content-type-get
1151 '("image/gif" (name . "b980912.gif")) 'name)
1152 @result{} "b980912.gif"
1155 @item mail-header-encode-parameter
1156 @findex mail-header-encode-parameter
1157 Takes a parameter string and returns an encoded version of the string.
1158 This is used for parameters in headers like @code{Content-Type} and
1159 @code{Content-Disposition}.
1161 @item mail-header-remove-comments
1162 @findex mail-header-remove-comments
1163 Return a comment-free version of a header.
1166 (mail-header-remove-comments
1167 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1168 @result{} "Gnus/5.070027 "
1171 @item mail-header-remove-whitespace
1172 @findex mail-header-remove-whitespace
1173 Remove linear white space from a header. Space inside quoted strings
1174 and comments is preserved.
1177 (mail-header-remove-whitespace
1178 "image/gif; name=\"Name with spaces\"")
1179 @result{} "image/gif;name=\"Name with spaces\""
1182 @item mail-header-get-comment
1183 @findex mail-header-get-comment
1184 Return the last comment in a header.
1187 (mail-header-get-comment
1188 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1189 @result{} "Finnish Landrace"
1192 @item mail-header-parse-address
1193 @findex mail-header-parse-address
1194 Parse an address and return a list containing the mailbox and the
1198 (mail-header-parse-address
1199 "Hrvoje Niksic <hniksic@@srce.hr>")
1200 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1203 @item mail-header-parse-addresses
1204 @findex mail-header-parse-addresses
1205 Parse a string with list of addresses and return a list of elements like
1206 the one described above.
1209 (mail-header-parse-addresses
1210 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1211 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1212 ("sb@@metis.no" . "Steinar Bang"))
1215 @item mail-header-parse-date
1216 @findex mail-header-parse-date
1217 Parse a date string and return an Emacs time structure.
1219 @item mail-narrow-to-head
1220 @findex mail-narrow-to-head
1221 Narrow the buffer to the header section of the buffer. Point is placed
1222 at the beginning of the narrowed buffer.
1224 @item mail-header-narrow-to-field
1225 @findex mail-header-narrow-to-field
1226 Narrow the buffer to the header under point. Understands continuation
1229 @item mail-header-fold-field
1230 @findex mail-header-fold-field
1231 Fold the header under point.
1233 @item mail-header-unfold-field
1234 @findex mail-header-unfold-field
1235 Unfold the header under point.
1237 @item mail-header-field-value
1238 @findex mail-header-field-value
1239 Return the value of the field under point.
1241 @item mail-encode-encoded-word-region
1242 @findex mail-encode-encoded-word-region
1243 Encode the non-@acronym{ASCII} words in the region. For instance,
1244 @samp{Naïve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1246 @item mail-encode-encoded-word-buffer
1247 @findex mail-encode-encoded-word-buffer
1248 Encode the non-@acronym{ASCII} words in the current buffer. This function is
1249 meant to be called narrowed to the headers of a message.
1251 @item mail-encode-encoded-word-string
1252 @findex mail-encode-encoded-word-string
1253 Encode the words that need encoding in a string, and return the result.
1256 (mail-encode-encoded-word-string
1257 "This is naïve, baby")
1258 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1261 @item mail-decode-encoded-word-region
1262 @findex mail-decode-encoded-word-region
1263 Decode the encoded words in the region.
1265 @item mail-decode-encoded-word-string
1266 @findex mail-decode-encoded-word-string
1267 Decode the encoded words in the string and return the result.
1270 (mail-decode-encoded-word-string
1271 "This is =?iso-8859-1?q?na=EFve,?= baby")
1272 @result{} "This is naïve, baby"
1277 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1278 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1279 in the subsequent sections.
1283 @node Basic Functions
1284 @chapter Basic Functions
1286 This chapter describes the basic, ground-level functions for parsing and
1287 handling. Covered here is parsing @code{From} lines, removing comments
1288 from header lines, decoding encoded words, parsing date headers and so
1289 on. High-level functionality is dealt with in the first chapter
1290 (@pxref{Decoding and Viewing}).
1293 * rfc2045:: Encoding @code{Content-Type} headers.
1294 * rfc2231:: Parsing @code{Content-Type} headers.
1295 * ietf-drums:: Handling mail headers defined by RFC822bis.
1296 * rfc2047:: En/decoding encoded words in headers.
1297 * time-date:: Functions for parsing dates and manipulating time.
1298 * qp:: Quoted-Printable en/decoding.
1299 * base64:: Base64 en/decoding.
1300 * binhex:: Binhex decoding.
1301 * uudecode:: Uuencode decoding.
1302 * yenc:: Yenc decoding.
1303 * rfc1843:: Decoding HZ-encoded text.
1304 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1311 RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would
1312 imagine that there would be a lot to implement. But there isn't, since
1313 most of the implementation details are delegated to the subsequent
1316 So @file{rfc2045.el} has only a single function:
1319 @item rfc2045-encode-string
1320 @findex rfc2045-encode-string
1321 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1322 @var{value} will be quoted if there are non-safe characters in it.
1329 RFC2231 defines a syntax for the @code{Content-Type} and
1330 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1331 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1334 In short, these headers look something like this:
1337 Content-Type: application/x-stuff;
1338 title*0*=us-ascii'en'This%20is%20even%20more%20;
1339 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1343 They usually aren't this bad, though.
1345 The following functions are defined by this library:
1348 @item rfc2231-parse-string
1349 @findex rfc2231-parse-string
1350 Parse a @code{Content-Type} header and return a list describing its
1354 (rfc2231-parse-string
1355 "application/x-stuff;
1356 title*0*=us-ascii'en'This%20is%20even%20more%20;
1357 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1358 title*2=\"isn't it!\"")
1359 @result{} ("application/x-stuff"
1360 (title . "This is even more ***fun*** isn't it!"))
1363 @item rfc2231-get-value
1364 @findex rfc2231-get-value
1365 Takes one of the lists on the format above and returns
1366 the value of the specified attribute.
1368 @item rfc2231-encode-string
1369 @findex rfc2231-encode-string
1370 Encode a parameter in headers likes @code{Content-Type} and
1371 @code{Content-Disposition}.
1379 @dfn{drums} is an IETF working group that is working on the replacement
1382 The functions provided by this library include:
1385 @item ietf-drums-remove-comments
1386 @findex ietf-drums-remove-comments
1387 Remove the comments from the argument and return the results.
1389 @item ietf-drums-remove-whitespace
1390 @findex ietf-drums-remove-whitespace
1391 Remove linear white space from the string and return the results.
1392 Spaces inside quoted strings and comments are left untouched.
1394 @item ietf-drums-get-comment
1395 @findex ietf-drums-get-comment
1396 Return the last most comment from the string.
1398 @item ietf-drums-parse-address
1399 @findex ietf-drums-parse-address
1400 Parse an address string and return a list that contains the mailbox and
1401 the plain text name.
1403 @item ietf-drums-parse-addresses
1404 @findex ietf-drums-parse-addresses
1405 Parse a string that contains any number of comma-separated addresses and
1406 return a list that contains mailbox/plain text pairs.
1408 @item ietf-drums-parse-date
1409 @findex ietf-drums-parse-date
1410 Parse a date string and return an Emacs time structure.
1412 @item ietf-drums-narrow-to-header
1413 @findex ietf-drums-narrow-to-header
1414 Narrow the buffer to the header section of the current buffer.
1422 RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how
1423 non-@acronym{ASCII} text in headers are to be encoded. This is actually rather
1424 complicated, so a number of variables are necessary to tweak what this
1427 The following variables are tweakable:
1430 @item rfc2047-header-encoding-alist
1431 @vindex rfc2047-header-encoding-alist
1432 This is an alist of header / encoding-type pairs. Its main purpose is
1433 to prevent encoding of certain headers.
1435 The keys can either be header regexps, or @code{t}.
1437 The values can be @code{nil}, in which case the header(s) in question
1438 won't be encoded, @code{mime}, which means that they will be encoded, or
1439 @code{address-mime}, which means the header(s) will be encoded carefully
1440 assuming they contain addresses.
1442 @item rfc2047-charset-encoding-alist
1443 @vindex rfc2047-charset-encoding-alist
1444 RFC2047 specifies two forms of encoding---@code{Q} (a
1445 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1446 specifies which charset should use which encoding.
1448 @item rfc2047-encode-function-alist
1449 @vindex rfc2047-encode-function-alist
1450 This is an alist of encoding / function pairs. The encodings are
1451 @code{Q}, @code{B} and @code{nil}.
1453 @item rfc2047-encoded-word-regexp
1454 @vindex rfc2047-encoded-word-regexp
1455 When decoding words, this library looks for matches to this regexp.
1457 @item rfc2047-encoded-word-regexp-loose
1458 @vindex rfc2047-encoded-word-regexp-loose
1459 This is a version from which the regexp for the Q encoding pattern of
1460 @code{rfc2047-encoded-word-regexp} is made loose.
1462 @item rfc2047-encode-encoded-words
1463 @vindex rfc2047-encode-encoded-words
1464 The boolean variable specifies whether encoded words
1465 (e.g., @samp{=?us-ascii?q?hello?=}) should be encoded again.
1466 @code{rfc2047-encoded-word-regexp} is used to look for such words.
1468 @item rfc2047-allow-irregular-q-encoded-words
1469 @vindex rfc2047-allow-irregular-q-encoded-words
1470 The boolean variable specifies whether irregular Q encoded words
1471 (e.g., @samp{=?us-ascii?q?hello??=}) should be decoded. If it is
1472 non-@code{nil}, @code{rfc2047-encoded-word-regexp-loose} is used instead
1473 of @code{rfc2047-encoded-word-regexp} to look for encoded words.
1477 Those were the variables, and these are this functions:
1480 @item rfc2047-narrow-to-field
1481 @findex rfc2047-narrow-to-field
1482 Narrow the buffer to the header on the current line.
1484 @item rfc2047-encode-message-header
1485 @findex rfc2047-encode-message-header
1486 Should be called narrowed to the header of a message. Encodes according
1487 to @code{rfc2047-header-encoding-alist}.
1489 @item rfc2047-encode-region
1490 @findex rfc2047-encode-region
1491 Encodes all encodable words in the region specified.
1493 @item rfc2047-encode-string
1494 @findex rfc2047-encode-string
1495 Encode a string and return the results.
1497 @item rfc2047-decode-region
1498 @findex rfc2047-decode-region
1499 Decode the encoded words in the region.
1501 @item rfc2047-decode-string
1502 @findex rfc2047-decode-string
1503 Decode a string and return the results.
1505 @item rfc2047-encode-parameter
1506 @findex rfc2047-encode-parameter
1507 Encode a parameter in the RFC2047-like style. This is a substitution
1508 for the @code{rfc2231-encode-string} function, that is the standard but
1509 many mailers don't support it. @xref{rfc2231}.
1517 While not really a part of the @acronym{MIME} library, it is convenient to
1518 document this library here. It deals with parsing @code{Date} headers
1519 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1522 These functions convert between five formats: A date string, an Emacs
1523 time structure, a decoded time list, a second number, and a day number.
1525 Here's a bunch of time/date/second/day examples:
1528 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1529 @result{} (54 21 12 12 9 1998 6 nil 7200)
1531 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1532 @result{} (13818 19266)
1534 (float-time '(13818 19266))
1535 @result{} 905595714.0
1537 (seconds-to-time 905595714.0)
1538 @result{} (13818 19266 0 0)
1540 (time-to-days '(13818 19266))
1543 (days-to-time 729644)
1544 @result{} (961933 512)
1546 (time-since '(13818 19266))
1547 @result{} (6797 9607 984839 247000)
1549 (time-less-p '(13818 19266) '(13818 19145))
1552 (subtract-time '(13818 19266) '(13818 19145))
1555 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1556 "Sat Sep 07 12:21:54 1998 +0200")
1559 (date-leap-year-p 2000)
1562 (time-to-day-in-year '(13818 19266))
1565 (time-to-number-of-days
1567 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1568 @result{} 4314.095589286675
1571 And finally, we have @code{safe-date-to-time}, which does the same as
1572 @code{date-to-time}, but returns a zero time if the date is
1573 syntactically malformed.
1575 The five data representations used are the following:
1579 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1580 12:21:54 1998 +0200"}.
1583 An internal Emacs time. For instance: @code{(13818 26466 0 0)}.
1586 A floating point representation of the internal Emacs time. For
1587 instance: @code{905595714.0}.
1590 An integer number representing the number of days since 00000101. For
1591 instance: @code{729644}.
1594 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1598 All the examples above represent the same moment.
1600 These are the functions available:
1604 Take a date and return a time.
1607 Take a time and return seconds. (This is a built-in function.)
1609 @item seconds-to-time
1610 Take seconds and return a time.
1613 Take a time and return days.
1616 Take days and return a time.
1619 Take a date and return days.
1621 @item time-to-number-of-days
1622 Take a time and return the number of days that represents.
1624 @item safe-date-to-time
1625 Take a date and return a time. If the date is not syntactically valid,
1626 return a ``zero'' time.
1629 Take two times and say whether the first time is less (i.e., earlier)
1630 than the second time.
1633 Take a time and return a time saying how long it was since that time.
1636 Take two times and subtract the second from the first. I.e., return
1637 the time between the two times.
1640 Take two days and return the number of days between those two days.
1642 @item date-leap-year-p
1643 Take a year number and say whether it's a leap year.
1645 @item time-to-day-in-year
1646 Take a time and return the day number within the year that the time is
1655 This library deals with decoding and encoding Quoted-Printable text.
1657 Very briefly explained, qp encoding means translating all 8-bit
1658 characters (and lots of control characters) into things that look like
1659 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1662 The following functions are defined by the library:
1665 @item quoted-printable-decode-region
1666 @findex quoted-printable-decode-region
1667 QP-decode all the encoded text in the specified region.
1669 @item quoted-printable-decode-string
1670 @findex quoted-printable-decode-string
1671 Decode the QP-encoded text in a string and return the results.
1673 @item quoted-printable-encode-region
1674 @findex quoted-printable-encode-region
1675 QP-encode all the encodable characters in the specified region. The third
1676 optional parameter @var{fold} specifies whether to fold long lines.
1677 (Long here means 72.)
1679 @item quoted-printable-encode-string
1680 @findex quoted-printable-encode-string
1681 QP-encode all the encodable characters in a string and return the
1691 Base64 is an encoding that encodes three bytes into four characters,
1692 thereby increasing the size by about 33%. The alphabet used for
1693 encoding is very resistant to mangling during transit.
1695 The following functions are defined by this library:
1698 @item base64-encode-region
1699 @findex base64-encode-region
1700 base64 encode the selected region. Return the length of the encoded
1701 text. Optional third argument @var{no-line-break} means do not break
1702 long lines into shorter lines.
1704 @item base64-encode-string
1705 @findex base64-encode-string
1706 base64 encode a string and return the result.
1708 @item base64-decode-region
1709 @findex base64-decode-region
1710 base64 decode the selected region. Return the length of the decoded
1711 text. If the region can't be decoded, return @code{nil} and don't
1714 @item base64-decode-string
1715 @findex base64-decode-string
1716 base64 decode a string and return the result. If the string can't be
1717 decoded, @code{nil} is returned.
1728 @code{binhex} is an encoding that originated in Macintosh environments.
1729 The following function is supplied to deal with these:
1732 @item binhex-decode-region
1733 @findex binhex-decode-region
1734 Decode the encoded text in the region. If given a third parameter, only
1735 decode the @code{binhex} header and return the filename.
1744 @code{uuencode} is probably still the most popular encoding of binaries
1745 used on Usenet, although @code{base64} rules the mail world.
1747 The following function is supplied by this package:
1750 @item uudecode-decode-region
1751 @findex uudecode-decode-region
1752 Decode the text in the region.
1760 @code{yenc} is used for encoding binaries on Usenet. The following
1761 function is supplied by this package:
1764 @item yenc-decode-region
1765 @findex yenc-decode-region
1766 Decode the encoded text in the region.
1777 RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In
1778 essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this:
1781 This sentence is in @acronym{ASCII}.
1782 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1785 Simple enough, and widely used in China.
1787 The following functions are available to handle this encoding:
1790 @item rfc1843-decode-region
1791 Decode HZ-encoded text in the region.
1793 @item rfc1843-decode-string
1794 Decode a HZ-encoded string and return the result.
1802 The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message
1803 handlers and describes how elements are supposed to be displayed.
1804 Here's an example file:
1808 audio/wav; wavplayer %s
1809 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1812 This says that all image files should be displayed with @code{gimp},
1813 that WAVE audio files should be played by @code{wavplayer}, and that
1814 MS-WORD files should be inlined by @code{catdoc}.
1816 The @code{mailcap} library parses this file, and provides functions for
1820 @item mailcap-mime-data
1821 @vindex mailcap-mime-data
1822 This variable is an alist of alists containing backup viewing rules.
1826 Interface functions:
1829 @item mailcap-parse-mailcaps
1830 @findex mailcap-parse-mailcaps
1831 Parse the @file{~/.mailcap} file.
1833 @item mailcap-mime-info
1834 Takes a @acronym{MIME} type as its argument and returns the matching viewer.
1844 The Emacs @acronym{MIME} library implements handling of various elements
1845 according to a (somewhat) large number of RFCs, drafts and standards
1846 documents. This chapter lists the relevant ones. They can all be
1847 fetched from @uref{http://quimby.gnus.org/notes/}.
1852 Standard for the Format of ARPA Internet Text Messages.
1855 Standard for Interchange of USENET Messages
1858 Format of Internet Message Bodies
1864 Message Header Extensions for Non-@acronym{ASCII} Text
1867 Registration Procedures
1870 Conformance Criteria and Examples
1873 @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets,
1874 Languages, and Continuations
1877 HZ---A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1878 @acronym{ASCII} characters
1880 @item draft-ietf-drums-msg-fmt-05.txt
1881 Draft for the successor of RFC822
1884 The @acronym{MIME} Multipart/Related Content-type
1887 The Multipart/Report Content Type for the Reporting of Mail System
1888 Administrative Messages
1891 Communicating Presentation Information in Internet Messages: The
1892 Content-Disposition Header Field
1895 Documentation of the text/plain format parameter for flowed text.
1899 @node GNU Free Documentation License
1900 @chapter GNU Free Documentation License
1901 @include doclicense.texi