3 @setfilename emacs-mime
4 @settitle Emacs MIME Manual
10 This file documents the Emacs MIME interface functionality.
12 Copyright @copyright{} 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
13 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
16 Permission is granted to copy, distribute and/or modify this document
17 under the terms of the GNU Free Documentation License, Version 1.3 or
18 any later version published by the Free Software Foundation; with no
19 Invariant Sections, with the Front-Cover texts being ``A GNU Manual'',
20 and with the Back-Cover Texts as in (a) below. A copy of the license
21 is included in the section entitled ``GNU Free Documentation License''.
23 (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
24 modify this GNU manual. Buying copies from the FSF supports it in
25 developing GNU and promoting software freedom.''
29 @c Node ``Interface Functions'' uses Latin-1 characters
30 @documentencoding ISO-8859-1
34 * Emacs MIME: (emacs-mime). Emacs MIME de/composition library.
39 @setchapternewpage odd
42 @title Emacs MIME Manual
44 @author by Lars Magne Ingebrigtsen
46 @vskip 0pt plus 1filll
55 This manual documents the libraries used to compose and display
56 @acronym{MIME} messages.
58 This manual is directed at users who want to modify the behavior of
59 the @acronym{MIME} encoding/decoding process or want a more detailed
60 picture of how the Emacs @acronym{MIME} library works, and people who want
61 to write functions and commands that manipulate @acronym{MIME} elements.
63 @acronym{MIME} is short for @dfn{Multipurpose Internet Mail Extensions}.
64 This standard is documented in a number of RFCs; mainly RFC2045 (Format
65 of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message
66 Header Extensions for Non-@acronym{ASCII} Text), RFC2048 (Registration
67 Procedures), RFC2049 (Conformance Criteria and Examples). It is highly
68 recommended that anyone who intends writing @acronym{MIME}-compliant software
69 read at least RFC2045 and RFC2047.
76 * Decoding and Viewing:: A framework for decoding and viewing.
77 * Composing:: @acronym{MML}; a language for describing @acronym{MIME} parts.
78 * Interface Functions:: An abstraction over the basic functions.
79 * Basic Functions:: Utility and basic parsing functions.
80 * Standards:: A summary of RFCs and working documents used.
81 * GNU Free Documentation License:: The license for this documentation.
82 * Index:: Function and variable index.
86 @node Decoding and Viewing
87 @chapter Decoding and Viewing
89 This chapter deals with decoding and viewing @acronym{MIME} messages on a
92 The main idea is to first analyze a @acronym{MIME} article, and then allow
93 other programs to do things based on the list of @dfn{handles} that are
94 returned as a result of this analysis.
97 * Dissection:: Analyzing a @acronym{MIME} message.
98 * Non-MIME:: Analyzing a non-@acronym{MIME} message.
99 * Handles:: Handle manipulations.
100 * Display:: Displaying handles.
101 * Display Customization:: Variables that affect display.
102 * Files and Directories:: Saving and naming attachments.
103 * New Viewers:: How to write your own viewers.
110 The @code{mm-dissect-buffer} is the function responsible for dissecting
111 a @acronym{MIME} article. If given a multipart message, it will recursively
112 descend the message, following the structure, and return a tree of
113 @acronym{MIME} handles that describes the structure of the message.
117 @vindex mm-uu-configure-list
119 Gnus also understands some non-@acronym{MIME} attachments, such as
120 postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp,
121 diff. Each of these features can be disabled by add an item into
122 @code{mm-uu-configure-list}. For example,
126 (add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
152 Non-@acronym{MIME} forwarded message.
160 @acronym{PGP} signed clear text.
163 @findex pgp-encrypted
164 @acronym{PGP} encrypted clear text.
168 @acronym{PGP} public keys.
171 @findex emacs-sources
172 @vindex mm-uu-emacs-sources-regexp
173 Emacs source code. This item works only in the groups matching
174 @code{mm-uu-emacs-sources-regexp}.
178 @vindex mm-uu-diff-groups-regexp
179 Patches. This is intended for groups where diffs of committed files
180 are automatically sent to. It only works in groups matching
181 @code{mm-uu-diff-groups-regexp}.
184 @cindex verbatim-marks
185 Slrn-style verbatim marks.
189 LaTeX documents. It only works in groups matching
190 @code{mm-uu-tex-groups-regexp}.
194 @cindex text/x-verbatim
195 @c Is @vindex suitable for a face?
196 @vindex mm-uu-extract
197 Some inlined non-@acronym{MIME} attachments are displayed using the face
198 @code{mm-uu-extract}. By default, no @acronym{MIME} button for these
199 parts is displayed. You can force displaying a button using @kbd{K b}
200 (@code{gnus-summary-display-buttonized}) or add @code{text/x-verbatim}
201 to @code{gnus-buttonized-mime-types}, @xref{MIME Commands, ,MIME
202 Commands, gnus, Gnus Manual}.
207 A @acronym{MIME} handle is a list that fully describes a @acronym{MIME}
210 The following macros can be used to access elements in a handle:
213 @item mm-handle-buffer
214 @findex mm-handle-buffer
215 Return the buffer that holds the contents of the undecoded @acronym{MIME}
219 @findex mm-handle-type
220 Return the parsed @code{Content-Type} of the part.
222 @item mm-handle-encoding
223 @findex mm-handle-encoding
224 Return the @code{Content-Transfer-Encoding} of the part.
226 @item mm-handle-undisplayer
227 @findex mm-handle-undisplayer
228 Return the object that can be used to remove the displayed part (if it
231 @item mm-handle-set-undisplayer
232 @findex mm-handle-set-undisplayer
233 Set the undisplayer object.
235 @item mm-handle-disposition
236 @findex mm-handle-disposition
237 Return the parsed @code{Content-Disposition} of the part.
239 @item mm-get-content-id
240 Returns the handle(s) referred to by @code{Content-ID}.
248 Functions for displaying, removing and saving.
251 @item mm-display-part
252 @findex mm-display-part
256 @findex mm-remove-part
257 Remove the part (if it has been displayed).
260 @findex mm-inlinable-p
261 Say whether a @acronym{MIME} type can be displayed inline.
263 @item mm-automatic-display-p
264 @findex mm-automatic-display-p
265 Say whether a @acronym{MIME} type should be displayed automatically.
267 @item mm-destroy-part
268 @findex mm-destroy-part
269 Free all resources occupied by a part.
273 Offer to save the part in a file.
277 Offer to pipe the part to some process.
279 @item mm-interactively-view-part
280 @findex mm-interactively-view-part
281 Prompt for a mailcap method to use to view the part.
286 @node Display Customization
287 @section Display Customization
291 @item mm-inline-media-tests
292 @vindex mm-inline-media-tests
293 This is an alist where the key is a @acronym{MIME} type, the second element
294 is a function to display the part @dfn{inline} (i.e., inside Emacs), and
295 the third element is a form to be @code{eval}ed to say whether the part
296 can be displayed inline.
298 This variable specifies whether a part @emph{can} be displayed inline,
299 and, if so, how to do it. It does not say whether parts are
300 @emph{actually} displayed inline.
302 @item mm-inlined-types
303 @vindex mm-inlined-types
304 This, on the other hand, says what types are to be displayed inline, if
305 they satisfy the conditions set by the variable above. It's a list of
306 @acronym{MIME} media types.
308 @item mm-automatic-display
309 @vindex mm-automatic-display
310 This is a list of types that are to be displayed ``automatically'', but
311 only if the above variable allows it. That is, only inlinable parts can
312 be displayed automatically.
314 @item mm-automatic-external-display
315 @vindex mm-automatic-external-display
316 This is a list of types that will be displayed automatically in an
319 @item mm-keep-viewer-alive-types
320 @vindex mm-keep-viewer-alive-types
321 This is a list of media types for which the external viewer will not
322 be killed when selecting a different article.
324 @item mm-attachment-override-types
325 @vindex mm-attachment-override-types
326 Some @acronym{MIME} agents create parts that have a content-disposition of
327 @samp{attachment}. This variable allows overriding that disposition and
328 displaying the part inline. (Note that the disposition is only
329 overridden if we are able to, and want to, display the part inline.)
331 @item mm-discouraged-alternatives
332 @vindex mm-discouraged-alternatives
333 List of @acronym{MIME} types that are discouraged when viewing
334 @samp{multipart/alternative}. Viewing agents are supposed to view the
335 last possible part of a message, as that is supposed to be the richest.
336 However, users may prefer other types instead, and this list says what
337 types are most unwanted. If, for instance, @samp{text/html} parts are
338 very unwanted, and @samp{text/richtext} parts are somewhat unwanted,
339 you could say something like:
342 (setq mm-discouraged-alternatives
343 '("text/html" "text/richtext")
345 (remove "text/html" mm-automatic-display))
348 Adding @code{"image/.*"} might also be useful. Spammers use images as
349 the preferred part of @samp{multipart/alternative} messages, so you might
350 not notice there are other parts. See also
351 @code{gnus-buttonized-mime-types}, @ref{MIME Commands, ,MIME Commands,
352 gnus, Gnus Manual}. After adding @code{"multipart/alternative"} to
353 @code{gnus-buttonized-mime-types} you can choose manually which
354 alternative you'd like to view. For example, you can set those
358 (setq gnus-buttonized-mime-types
359 '("multipart/alternative" "multipart/signed")
360 mm-discouraged-alternatives
361 '("text/html" "image/.*"))
364 In this case, Gnus will display radio buttons for such a kind of spam
368 1. (*) multipart/alternative ( ) image/gif
370 2. (*) text/plain ( ) text/html
373 @item mm-inline-large-images
374 @vindex mm-inline-large-images
375 When displaying inline images that are larger than the window, Emacs
376 does not enable scrolling, which means that you cannot see the whole
377 image. To prevent this, the library tries to determine the image size
378 before displaying it inline, and if it doesn't fit the window, the
379 library will display it externally (e.g. with @samp{ImageMagick} or
380 @samp{xv}). Setting this variable to @code{t} disables this check and
381 makes the library display all inline images as inline, regardless of
382 their size. If you set this variable to @code{resize}, the image will
383 be displayed resized to fit in the window, if Emacs has the ability to
386 @item mm-inline-large-images-proportion
387 @vindex mm-inline-images-max-proportion
388 The proportion used when resizing large images.
390 @item mm-inline-override-types
391 @vindex mm-inline-override-types
392 @code{mm-inlined-types} may include regular expressions, for example to
393 specify that all @samp{text/.*} parts be displayed inline. If a user
394 prefers to have a type that matches such a regular expression be treated
395 as an attachment, that can be accomplished by setting this variable to a
396 list containing that type. For example assuming @code{mm-inlined-types}
397 includes @samp{text/.*}, then including @samp{text/html} in this
398 variable will cause @samp{text/html} parts to be treated as attachments.
400 @item mm-text-html-renderer
401 @vindex mm-text-html-renderer
402 This selects the function used to render @acronym{HTML}. The predefined
403 renderers are selected by the symbols @code{gnus-article-html}, @code{w3},
404 @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
405 information about emacs-w3m}, @code{links}, @code{lynx},
406 @code{w3m-standalone} or @code{html2text}. If @code{nil} use an
407 external viewer. You can also specify a function, which will be
408 called with a @acronym{MIME} handle as the argument.
410 @item mm-inline-text-html-with-images
411 @vindex mm-inline-text-html-with-images
412 Some @acronym{HTML} mails might have the trick of spammers using
413 @samp{<img>} tags. It is likely to be intended to verify whether you
414 have read the mail. You can prevent your personal informations from
415 leaking by setting this option to @code{nil} (which is the default).
416 It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
417 command @kbd{t} on the image anchor to show an image even if it is
418 @code{nil}.@footnote{The command @kbd{T} will load all images. If you
419 have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
422 @item mm-w3m-safe-url-regexp
423 @vindex mm-w3m-safe-url-regexp
424 A regular expression that matches safe URL names, i.e. URLs that are
425 unlikely to leak personal information when rendering @acronym{HTML}
426 email (the default value is @samp{\\`cid:}). If @code{nil} consider
427 all URLs safe. In Gnus, this will be overridden according to the value
428 of the variable @code{gnus-safe-html-newsgroups}, @xref{Various
429 Various, ,Various Various, gnus, Gnus Manual}.
431 @item mm-inline-text-html-with-w3m-keymap
432 @vindex mm-inline-text-html-with-w3m-keymap
433 You can use emacs-w3m command keys in the inlined text/html part by
434 setting this option to non-@code{nil}. The default value is @code{t}.
436 @item mm-external-terminal-program
437 @vindex mm-external-terminal-program
438 The program used to start an external terminal.
440 @item mm-enable-external
441 @vindex mm-enable-external
442 Indicate whether external @acronym{MIME} handlers should be used.
444 If @code{t}, all defined external @acronym{MIME} handlers are used. If
445 @code{nil}, files are saved to disk (@code{mailcap-save-binary-file}).
446 If it is the symbol @code{ask}, you are prompted before the external
447 @acronym{MIME} handler is invoked.
449 When you launch an attachment through mailcap (@pxref{mailcap}) an
450 attempt is made to use a safe viewer with the safest options---this isn't
451 the case if you save it to disk and launch it in a different way
452 (command line or double-clicking). Anyhow, if you want to be sure not
453 to launch any external programs, set this variable to @code{nil} or
458 @node Files and Directories
459 @section Files and Directories
463 @item mm-default-directory
464 @vindex mm-default-directory
465 The default directory for saving attachments. If @code{nil} use
466 @code{default-directory}.
468 @item mm-tmp-directory
469 @vindex mm-tmp-directory
470 Directory for storing temporary files.
472 @item mm-file-name-rewrite-functions
473 @vindex mm-file-name-rewrite-functions
474 A list of functions used for rewriting file names of @acronym{MIME}
475 parts. Each function is applied successively to the file name.
476 Ready-made functions include
479 @item mm-file-name-delete-control
480 @findex mm-file-name-delete-control
481 Delete all control characters.
483 @item mm-file-name-delete-gotchas
484 @findex mm-file-name-delete-gotchas
485 Delete characters that could have unintended consequences when used
486 with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and
487 @samp{-}, @samp{.} as the first character.
489 @item mm-file-name-delete-whitespace
490 @findex mm-file-name-delete-whitespace
491 Remove all whitespace.
493 @item mm-file-name-trim-whitespace
494 @findex mm-file-name-trim-whitespace
495 Remove leading and trailing whitespace.
497 @item mm-file-name-collapse-whitespace
498 @findex mm-file-name-collapse-whitespace
499 Collapse multiple whitespace characters.
501 @item mm-file-name-replace-whitespace
502 @findex mm-file-name-replace-whitespace
503 @vindex mm-file-name-replace-whitespace
504 Replace whitespace with underscores. Set the variable
505 @code{mm-file-name-replace-whitespace} to any other string if you do
506 not like underscores.
509 The standard Emacs functions @code{capitalize}, @code{downcase},
510 @code{upcase} and @code{upcase-initials} might also prove useful.
512 @item mm-path-name-rewrite-functions
513 @vindex mm-path-name-rewrite-functions
514 List of functions used for rewriting the full file names of @acronym{MIME}
515 parts. This is used when viewing parts externally, and is meant for
516 transforming the absolute name so that non-compliant programs can find
517 the file where it's saved.
524 Here's an example viewer for displaying @code{text/enriched} inline:
527 (defun mm-display-enriched-inline (handle)
530 (mm-insert-part handle)
531 (save-window-excursion
532 (enriched-decode (point-min) (point-max))
533 (setq text (buffer-string))))
534 (mm-insert-inline handle text)))
537 We see that the function takes a @acronym{MIME} handle as its parameter. It
538 then goes to a temporary buffer, inserts the text of the part, does some
539 work on the text, stores the result, goes back to the buffer it was
540 called from and inserts the result.
542 The two important helper functions here are @code{mm-insert-part} and
543 @code{mm-insert-inline}. The first function inserts the text of the
544 handle in the current buffer. It handles charset and/or content
545 transfer decoding. The second function just inserts whatever text you
546 tell it to insert, but it also sets things up so that the text can be
547 ``undisplayed'' in a convenient manner.
553 @cindex MIME Composing
555 @cindex MIME Meta Language
557 Creating a @acronym{MIME} message is boring and non-trivial. Therefore,
558 a library called @code{mml} has been defined that parses a language
559 called @acronym{MML} (@acronym{MIME} Meta Language) and generates
560 @acronym{MIME} messages.
562 @findex mml-generate-mime
563 The main interface function is @code{mml-generate-mime}. It will
564 examine the contents of the current (narrowed-to) buffer and return a
565 string containing the @acronym{MIME} message.
568 * Simple MML Example:: An example @acronym{MML} document.
569 * MML Definition:: All valid @acronym{MML} elements.
570 * Advanced MML Example:: Another example @acronym{MML} document.
571 * Encoding Customization:: Variables that affect encoding.
572 * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}.
573 * Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa.
574 * Flowed text:: Soft and hard newlines.
578 @node Simple MML Example
579 @section Simple MML Example
581 Here's a simple @samp{multipart/alternative}:
584 <#multipart type=alternative>
585 This is a plain text part.
586 <#part type=text/enriched>
587 <center>This is a centered enriched part</center>
591 After running this through @code{mml-generate-mime}, we get this:
594 Content-Type: multipart/alternative; boundary="=-=-="
600 This is a plain text part.
603 Content-Type: text/enriched
606 <center>This is a centered enriched part</center>
613 @section MML Definition
615 The @acronym{MML} language is very simple. It looks a bit like an SGML
616 application, but it's not.
618 The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a
619 different type or use a different charset. The way to delineate a part
620 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
621 with the @samp{<#multipart ...>} tag. Parts are ended by the
622 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
623 @samp{<#part ...>} tags are also closed by the next open tag.
625 There's also the @samp{<#external ...>} tag. These introduce
626 @samp{external/message-body} parts.
628 Each tag can contain zero or more parameters on the form
629 @samp{parameter=value}. The values may be enclosed in quotation marks,
630 but that's not necessary unless the value contains white space. So
631 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
633 The following parameters have meaning in @acronym{MML}; parameters that have no
634 meaning are ignored. The @acronym{MML} parameter names are the same as the
635 @acronym{MIME} parameter names; the things in the parentheses say which
636 header it will be used in.
640 The @acronym{MIME} type of the part (@code{Content-Type}).
643 Use the contents of the file in the body of the part
644 (@code{Content-Disposition}).
647 The contents of the body of the part are to be encoded in the character
648 set specified (@code{Content-Type}). @xref{Charset Translation}.
651 Might be used to suggest a file name if the part is to be saved
652 to a file (@code{Content-Type}).
655 Valid values are @samp{inline} and @samp{attachment}
656 (@code{Content-Disposition}).
659 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
660 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
664 A description of the part (@code{Content-Description}).
667 RFC822 date when the part was created (@code{Content-Disposition}).
669 @item modification-date
670 RFC822 date when the part was modified (@code{Content-Disposition}).
673 RFC822 date when the part was read (@code{Content-Disposition}).
676 Who to encrypt/sign the part to. This field is used to override any
677 auto-detection based on the To/CC headers.
680 Identity used to sign the part. This field is used to override the
684 The size (in octets) of the part (@code{Content-Disposition}).
687 What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp}
691 What technology to encrypt this @acronym{MML} part with (@code{smime},
692 @code{pgp} or @code{pgpmime})
696 Parameters for @samp{text/plain}:
700 Formatting parameter for the text, valid values include @samp{fixed}
701 (the default) and @samp{flowed}. Normally you do not specify this
702 manually, since it requires the textual body to be formatted in a
703 special way described in RFC 2646. @xref{Flowed text}.
706 Parameters for @samp{application/octet-stream}:
710 Type of the part; informal---meant for human readers
711 (@code{Content-Type}).
714 Parameters for @samp{message/external-body}:
718 A word indicating the supported access mechanism by which the file may
719 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
720 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
723 The RFC822 date after which the file may no longer be fetched.
724 (@code{Content-Type}.)
727 The size (in octets) of the file. (@code{Content-Type}.)
730 Valid values are @samp{read} and @samp{read-write}
731 (@code{Content-Type}).
735 Parameters for @samp{sign=smime}:
740 File containing key and certificate for signer.
744 Parameters for @samp{encrypt=smime}:
749 File containing certificate for recipient.
754 @node Advanced MML Example
755 @section Advanced MML Example
757 Here's a complex multipart message. It's a @samp{multipart/mixed} that
758 contains many parts, one of which is a @samp{multipart/alternative}.
761 <#multipart type=mixed>
762 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
763 <#multipart type=alternative>
764 This is a plain text part.
765 <#part type=text/enriched name=enriched.txt>
766 <center>This is a centered enriched part</center>
768 This is a new plain text part.
769 <#part disposition=attachment>
770 This plain text part is an attachment.
774 And this is the resulting @acronym{MIME} message:
777 Content-Type: multipart/mixed; boundary="=-=-="
785 Content-Type: image/jpeg;
787 Content-Disposition: inline;
789 Content-Transfer-Encoding: base64
791 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
792 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
793 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
794 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
795 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
796 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
797 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
798 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
799 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
800 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
801 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
802 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
803 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
804 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
805 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
806 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
807 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
810 Content-Type: multipart/alternative; boundary="==-=-="
816 This is a plain text part.
819 Content-Type: text/enriched;
823 <center>This is a centered enriched part</center>
829 This is a new plain text part.
832 Content-Disposition: attachment
835 This plain text part is an attachment.
840 @node Encoding Customization
841 @section Encoding Customization
845 @item mm-body-charset-encoding-alist
846 @vindex mm-body-charset-encoding-alist
847 Mapping from @acronym{MIME} charset to encoding to use. This variable is
848 usually used except, e.g., when other requirements force a specific
849 encoding (digitally signed messages require 7bit encodings). The
853 ((iso-2022-jp . 7bit)
854 (iso-2022-jp-2 . 7bit)
860 As an example, if you do not want to have ISO-8859-1 characters
861 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
862 this variable. You can override this setting on a per-message basis
863 by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
865 @item mm-coding-system-priorities
866 @vindex mm-coding-system-priorities
867 Prioritize coding systems to use for outgoing messages. The default
868 is @code{nil}, which means to use the defaults in Emacs, but is
869 @code{(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)} when
870 running Emacs in the Japanese language environment. It is a list of
871 coding system symbols (aliases of coding systems are also allowed, use
872 @kbd{M-x describe-coding-system} to make sure you are specifying correct
873 coding system names). For example, if you have configured Emacs
874 to prefer UTF-8, but wish that outgoing messages should be sent in
875 ISO-8859-1 if possible, you can set this variable to
876 @code{(iso-8859-1)}. You can override this setting on a per-message
877 basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}).
879 As different hierarchies prefer different charsets, you may want to set
880 @code{mm-coding-system-priorities} according to the hierarchy in Gnus.
883 @c Corrections about preferred charsets are welcome. de, fr and fj
884 @c should be correct, I don't know about the rest (so these are only
887 (add-to-list 'gnus-newsgroup-variables 'mm-coding-system-priorities)
888 (setq gnus-parameters
890 ;; Some charsets are just examples!
891 '(("^cn\\." ;; Chinese
892 (mm-coding-system-priorities
893 '(iso-8859-1 cn-big5 chinese-iso-7bit utf-8)))
894 ("^cz\\.\\|^pl\\." ;; Central and Eastern European
895 (mm-coding-system-priorities '(iso-8859-2 utf-8)))
896 ("^de\\." ;; German language
897 (mm-coding-system-priorities '(iso-8859-1 iso-8859-15 utf-8)))
899 (mm-coding-system-priorities '(iso-8859-15 iso-8859-1 utf-8)))
900 ("^fj\\." ;; Japanese
901 (mm-coding-system-priorities
902 '(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)))
903 ("^ru\\." ;; Cyrillic
904 (mm-coding-system-priorities
905 '(koi8-r iso-8859-5 iso-8859-1 utf-8))))
909 @item mm-content-transfer-encoding-defaults
910 @vindex mm-content-transfer-encoding-defaults
911 Mapping from @acronym{MIME} types to encoding to use. This variable is usually
912 used except, e.g., when other requirements force a safer encoding
913 (digitally signed messages require 7bit encoding). Besides the normal
914 @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
915 each case the most efficient of quoted-printable and base64 should be
918 @code{qp-or-base64} has another effect. It will fold long lines so that
919 MIME parts may not be broken by MTA. So do @code{quoted-printable} and
922 Note that it affects body encoding only when a part is a raw forwarded
923 message (which will be made by @code{gnus-summary-mail-forward} with the
924 arg 2 for example) or is neither the @samp{text/*} type nor the
925 @samp{message/*} type. Even though in those cases, you can override
926 this setting on a per-message basis by using the @code{encoding}
927 @acronym{MML} tag (@pxref{MML Definition}).
929 @item mm-use-ultra-safe-encoding
930 @vindex mm-use-ultra-safe-encoding
931 When this is non-@code{nil}, it means that textual parts are encoded as
932 quoted-printable if they contain lines longer than 76 characters or
933 starting with "From " in the body. Non-7bit encodings (8bit, binary)
934 are generally disallowed. This reduce the probability that a non-8bit
935 clean MTA or MDA changes the message. This should never be set
936 directly, but bound by other functions when necessary (e.g., when
937 encoding messages that are to be digitally signed).
941 @node Charset Translation
942 @section Charset Translation
945 During translation from @acronym{MML} to @acronym{MIME}, for each
946 @acronym{MIME} part which has been composed inside Emacs, an appropriate
947 charset has to be chosen.
949 @vindex mail-parse-charset
950 If you are running a non-@sc{mule} Emacs, this process is simple: If the
951 part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset
952 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
953 variable directly, though. If you want to change the default charset,
954 please consult the documentation of the package which you use to process
955 @acronym{MIME} messages.
956 @xref{Various Message Variables, , Various Message Variables, message,
957 Message Manual}, for example.)
958 If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is
964 @vindex mm-mime-mule-charset-alist
965 Things are slightly more complicated when running Emacs with @sc{mule}
966 support. In this case, a list of the @sc{mule} charsets used in the
967 part is obtained, and the @sc{mule} charsets are translated to
968 @acronym{MIME} charsets by consulting the table provided by Emacs itself
969 or the variable @code{mm-mime-mule-charset-alist} for XEmacs.
970 If this results in a single @acronym{MIME} charset, this is used to encode
971 the part. But if the resulting list of @acronym{MIME} charsets contains more
972 than one element, two things can happen: If it is possible to encode the
973 part via UTF-8, this charset is used. (For this, Emacs must support
974 the @code{utf-8} coding system, and the part must consist entirely of
975 characters which have Unicode counterparts.) If UTF-8 is not available
976 for some reason, the part is split into several ones, so that each one
977 can be encoded with a single @acronym{MIME} charset. The part can only be
978 split at line boundaries, though---if more than one @acronym{MIME} charset is
979 required to encode a single line, it is not possible to encode the part.
981 When running Emacs with @sc{mule} support, the preferences for which
982 coding system to use is inherited from Emacs itself. This means that
983 if Emacs is set up to prefer UTF-8, it will be used when encoding
984 messages. You can modify this by altering the
985 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
988 The charset to be used can be overridden by setting the @code{charset}
989 @acronym{MML} tag (@pxref{MML Definition}) when composing the message.
991 The encoding of characters (quoted-printable, 8bit etc) is orthogonal
992 to the discussion here, and is controlled by the variables
993 @code{mm-body-charset-encoding-alist} and
994 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
1001 A (multipart) @acronym{MIME} message can be converted to @acronym{MML}
1002 with the @code{mime-to-mml} function. It works on the message in the
1003 current buffer, and substitutes @acronym{MML} markup for @acronym{MIME}
1004 boundaries. Non-textual parts do not have their contents in the buffer,
1005 but instead have the contents in separate buffers that are referred to
1006 from the @acronym{MML} tags.
1009 An @acronym{MML} message can be converted back to @acronym{MIME} by the
1010 @code{mml-to-mime} function.
1012 These functions are in certain senses ``lossy''---you will not get back
1013 an identical message if you run @code{mime-to-mml} and then
1014 @code{mml-to-mime}. Not only will trivial things like the order of the
1015 headers differ, but the contents of the headers may also be different.
1016 For instance, the original message may use base64 encoding on text,
1017 while @code{mml-to-mime} may decide to use quoted-printable encoding, and
1020 In essence, however, these two functions should be the inverse of each
1021 other. The resulting contents of the message should remain equivalent,
1026 @section Flowed text
1027 @cindex format=flowed
1029 The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines}
1030 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
1031 emacs, Emacs Manual}) when encoding a message, and the
1032 ``format=flowed'' Content-Type parameter when decoding a message.
1034 On encoding text, regardless of @code{use-hard-newlines}, lines
1035 terminated by soft newline characters are filled together and wrapped
1036 after the column decided by @code{fill-flowed-encode-column}.
1037 Quotation marks (matching @samp{^>* ?}) are respected. The variable
1038 controls how the text will look in a client that does not support
1039 flowed text, the default is to wrap after 66 characters. If hard
1040 newline characters are not present in the buffer, no flow encoding
1043 On decoding flowed text, lines with soft newline characters are filled
1044 together and wrapped after the column decided by
1045 @code{fill-flowed-display-column}. The default is to wrap after
1049 @item mm-fill-flowed
1050 @vindex mm-fill-flowed
1051 If non-@code{nil} a format=flowed article will be displayed flowed.
1055 @node Interface Functions
1056 @chapter Interface Functions
1057 @cindex interface functions
1060 The @code{mail-parse} library is an abstraction over the actual
1061 low-level libraries that are described in the next chapter.
1063 Standards change, and so programs have to change to fit in the new
1064 mold. For instance, RFC2045 describes a syntax for the
1065 @code{Content-Type} header that only allows @acronym{ASCII} characters in the
1066 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
1067 for continuation headers and non-@acronym{ASCII} characters.
1069 The traditional way to deal with this is just to update the library
1070 functions to parse the new syntax. However, this is sometimes the wrong
1071 thing to do. In some instances it may be vital to be able to understand
1072 both the old syntax as well as the new syntax, and if there is only one
1073 library, one must choose between the old version of the library and the
1074 new version of the library.
1076 The Emacs @acronym{MIME} library takes a different tack. It defines a
1077 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
1078 and so on) that parses strictly according to the corresponding
1079 standard. However, normal programs would not use the functions
1080 provided by these libraries directly, but instead use the functions
1081 provided by the @code{mail-parse} library. The functions in this
1082 library are just aliases to the corresponding functions in the latest
1083 low-level libraries. Using this scheme, programs get a consistent
1084 interface they can use, and library developers are free to create
1085 write code that handles new standards.
1087 The following functions are defined by this library:
1090 @item mail-header-parse-content-type
1091 @findex mail-header-parse-content-type
1092 Parse a @code{Content-Type} header and return a list on the following
1097 (attribute1 . value1)
1098 (attribute2 . value2)
1105 (mail-header-parse-content-type
1106 "image/gif; name=\"b980912.gif\"")
1107 @result{} ("image/gif" (name . "b980912.gif"))
1110 @item mail-header-parse-content-disposition
1111 @findex mail-header-parse-content-disposition
1112 Parse a @code{Content-Disposition} header and return a list on the same
1113 format as the function above.
1115 @item mail-content-type-get
1116 @findex mail-content-type-get
1117 Takes two parameters---a list on the format above, and an attribute.
1118 Returns the value of the attribute.
1121 (mail-content-type-get
1122 '("image/gif" (name . "b980912.gif")) 'name)
1123 @result{} "b980912.gif"
1126 @item mail-header-encode-parameter
1127 @findex mail-header-encode-parameter
1128 Takes a parameter string and returns an encoded version of the string.
1129 This is used for parameters in headers like @code{Content-Type} and
1130 @code{Content-Disposition}.
1132 @item mail-header-remove-comments
1133 @findex mail-header-remove-comments
1134 Return a comment-free version of a header.
1137 (mail-header-remove-comments
1138 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1139 @result{} "Gnus/5.070027 "
1142 @item mail-header-remove-whitespace
1143 @findex mail-header-remove-whitespace
1144 Remove linear white space from a header. Space inside quoted strings
1145 and comments is preserved.
1148 (mail-header-remove-whitespace
1149 "image/gif; name=\"Name with spaces\"")
1150 @result{} "image/gif;name=\"Name with spaces\""
1153 @item mail-header-get-comment
1154 @findex mail-header-get-comment
1155 Return the last comment in a header.
1158 (mail-header-get-comment
1159 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1160 @result{} "Finnish Landrace"
1163 @item mail-header-parse-address
1164 @findex mail-header-parse-address
1165 Parse an address and return a list containing the mailbox and the
1169 (mail-header-parse-address
1170 "Hrvoje Niksic <hniksic@@srce.hr>")
1171 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1174 @item mail-header-parse-addresses
1175 @findex mail-header-parse-addresses
1176 Parse a string with list of addresses and return a list of elements like
1177 the one described above.
1180 (mail-header-parse-addresses
1181 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1182 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1183 ("sb@@metis.no" . "Steinar Bang"))
1186 @item mail-header-parse-date
1187 @findex mail-header-parse-date
1188 Parse a date string and return an Emacs time structure.
1190 @item mail-narrow-to-head
1191 @findex mail-narrow-to-head
1192 Narrow the buffer to the header section of the buffer. Point is placed
1193 at the beginning of the narrowed buffer.
1195 @item mail-header-narrow-to-field
1196 @findex mail-header-narrow-to-field
1197 Narrow the buffer to the header under point. Understands continuation
1200 @item mail-header-fold-field
1201 @findex mail-header-fold-field
1202 Fold the header under point.
1204 @item mail-header-unfold-field
1205 @findex mail-header-unfold-field
1206 Unfold the header under point.
1208 @item mail-header-field-value
1209 @findex mail-header-field-value
1210 Return the value of the field under point.
1212 @item mail-encode-encoded-word-region
1213 @findex mail-encode-encoded-word-region
1214 Encode the non-@acronym{ASCII} words in the region. For instance,
1215 @samp{Na@"{@dotless{i}}ve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1217 @item mail-encode-encoded-word-buffer
1218 @findex mail-encode-encoded-word-buffer
1219 Encode the non-@acronym{ASCII} words in the current buffer. This function is
1220 meant to be called narrowed to the headers of a message.
1222 @item mail-encode-encoded-word-string
1223 @findex mail-encode-encoded-word-string
1224 Encode the words that need encoding in a string, and return the result.
1227 (mail-encode-encoded-word-string
1228 "This is na@"{@dotless{i}}ve, baby")
1229 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1232 @item mail-decode-encoded-word-region
1233 @findex mail-decode-encoded-word-region
1234 Decode the encoded words in the region.
1236 @item mail-decode-encoded-word-string
1237 @findex mail-decode-encoded-word-string
1238 Decode the encoded words in the string and return the result.
1241 (mail-decode-encoded-word-string
1242 "This is =?iso-8859-1?q?na=EFve,?= baby")
1243 @result{} "This is na@"{@dotless{i}}ve, baby"
1248 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1249 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1250 in the subsequent sections.
1254 @node Basic Functions
1255 @chapter Basic Functions
1257 This chapter describes the basic, ground-level functions for parsing and
1258 handling. Covered here is parsing @code{From} lines, removing comments
1259 from header lines, decoding encoded words, parsing date headers and so
1260 on. High-level functionality is dealt with in the first chapter
1261 (@pxref{Decoding and Viewing}).
1264 * rfc2045:: Encoding @code{Content-Type} headers.
1265 * rfc2231:: Parsing @code{Content-Type} headers.
1266 * ietf-drums:: Handling mail headers defined by RFC822bis.
1267 * rfc2047:: En/decoding encoded words in headers.
1268 * time-date:: Functions for parsing dates and manipulating time.
1269 * qp:: Quoted-Printable en/decoding.
1270 * base64:: Base64 en/decoding.
1271 * binhex:: Binhex decoding.
1272 * uudecode:: Uuencode decoding.
1273 * yenc:: Yenc decoding.
1274 * rfc1843:: Decoding HZ-encoded text.
1275 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1282 RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would
1283 imagine that there would be a lot to implement. But there isn't, since
1284 most of the implementation details are delegated to the subsequent
1287 So @file{rfc2045.el} has only a single function:
1290 @item rfc2045-encode-string
1291 @findex rfc2045-encode-string
1292 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1293 @var{value} will be quoted if there are non-safe characters in it.
1300 RFC2231 defines a syntax for the @code{Content-Type} and
1301 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1302 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1305 In short, these headers look something like this:
1308 Content-Type: application/x-stuff;
1309 title*0*=us-ascii'en'This%20is%20even%20more%20;
1310 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1314 They usually aren't this bad, though.
1316 The following functions are defined by this library:
1319 @item rfc2231-parse-string
1320 @findex rfc2231-parse-string
1321 Parse a @code{Content-Type} header and return a list describing its
1325 (rfc2231-parse-string
1326 "application/x-stuff;
1327 title*0*=us-ascii'en'This%20is%20even%20more%20;
1328 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1329 title*2=\"isn't it!\"")
1330 @result{} ("application/x-stuff"
1331 (title . "This is even more ***fun*** isn't it!"))
1334 @item rfc2231-get-value
1335 @findex rfc2231-get-value
1336 Takes one of the lists on the format above and returns
1337 the value of the specified attribute.
1339 @item rfc2231-encode-string
1340 @findex rfc2231-encode-string
1341 Encode a parameter in headers likes @code{Content-Type} and
1342 @code{Content-Disposition}.
1350 @dfn{drums} is an IETF working group that is working on the replacement
1353 The functions provided by this library include:
1356 @item ietf-drums-remove-comments
1357 @findex ietf-drums-remove-comments
1358 Remove the comments from the argument and return the results.
1360 @item ietf-drums-remove-whitespace
1361 @findex ietf-drums-remove-whitespace
1362 Remove linear white space from the string and return the results.
1363 Spaces inside quoted strings and comments are left untouched.
1365 @item ietf-drums-get-comment
1366 @findex ietf-drums-get-comment
1367 Return the last most comment from the string.
1369 @item ietf-drums-parse-address
1370 @findex ietf-drums-parse-address
1371 Parse an address string and return a list that contains the mailbox and
1372 the plain text name.
1374 @item ietf-drums-parse-addresses
1375 @findex ietf-drums-parse-addresses
1376 Parse a string that contains any number of comma-separated addresses and
1377 return a list that contains mailbox/plain text pairs.
1379 @item ietf-drums-parse-date
1380 @findex ietf-drums-parse-date
1381 Parse a date string and return an Emacs time structure.
1383 @item ietf-drums-narrow-to-header
1384 @findex ietf-drums-narrow-to-header
1385 Narrow the buffer to the header section of the current buffer.
1393 RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how
1394 non-@acronym{ASCII} text in headers are to be encoded. This is actually rather
1395 complicated, so a number of variables are necessary to tweak what this
1398 The following variables are tweakable:
1401 @item rfc2047-header-encoding-alist
1402 @vindex rfc2047-header-encoding-alist
1403 This is an alist of header / encoding-type pairs. Its main purpose is
1404 to prevent encoding of certain headers.
1406 The keys can either be header regexps, or @code{t}.
1408 The values can be @code{nil}, in which case the header(s) in question
1409 won't be encoded, @code{mime}, which means that they will be encoded, or
1410 @code{address-mime}, which means the header(s) will be encoded carefully
1411 assuming they contain addresses.
1413 @item rfc2047-charset-encoding-alist
1414 @vindex rfc2047-charset-encoding-alist
1415 RFC2047 specifies two forms of encoding---@code{Q} (a
1416 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1417 specifies which charset should use which encoding.
1419 @item rfc2047-encode-function-alist
1420 @vindex rfc2047-encode-function-alist
1421 This is an alist of encoding / function pairs. The encodings are
1422 @code{Q}, @code{B} and @code{nil}.
1424 @item rfc2047-encoded-word-regexp
1425 @vindex rfc2047-encoded-word-regexp
1426 When decoding words, this library looks for matches to this regexp.
1428 @item rfc2047-encoded-word-regexp-loose
1429 @vindex rfc2047-encoded-word-regexp-loose
1430 This is a version from which the regexp for the Q encoding pattern of
1431 @code{rfc2047-encoded-word-regexp} is made loose.
1433 @item rfc2047-encode-encoded-words
1434 @vindex rfc2047-encode-encoded-words
1435 The boolean variable specifies whether encoded words
1436 (e.g. @samp{=?us-ascii?q?hello?=}) should be encoded again.
1437 @code{rfc2047-encoded-word-regexp} is used to look for such words.
1439 @item rfc2047-allow-irregular-q-encoded-words
1440 @vindex rfc2047-allow-irregular-q-encoded-words
1441 The boolean variable specifies whether irregular Q encoded words
1442 (e.g. @samp{=?us-ascii?q?hello??=}) should be decoded. If it is
1443 non-@code{nil}, @code{rfc2047-encoded-word-regexp-loose} is used instead
1444 of @code{rfc2047-encoded-word-regexp} to look for encoded words.
1448 Those were the variables, and these are this functions:
1451 @item rfc2047-narrow-to-field
1452 @findex rfc2047-narrow-to-field
1453 Narrow the buffer to the header on the current line.
1455 @item rfc2047-encode-message-header
1456 @findex rfc2047-encode-message-header
1457 Should be called narrowed to the header of a message. Encodes according
1458 to @code{rfc2047-header-encoding-alist}.
1460 @item rfc2047-encode-region
1461 @findex rfc2047-encode-region
1462 Encodes all encodable words in the region specified.
1464 @item rfc2047-encode-string
1465 @findex rfc2047-encode-string
1466 Encode a string and return the results.
1468 @item rfc2047-decode-region
1469 @findex rfc2047-decode-region
1470 Decode the encoded words in the region.
1472 @item rfc2047-decode-string
1473 @findex rfc2047-decode-string
1474 Decode a string and return the results.
1476 @item rfc2047-encode-parameter
1477 @findex rfc2047-encode-parameter
1478 Encode a parameter in the RFC2047-like style. This is a substitution
1479 for the @code{rfc2231-encode-string} function, that is the standard but
1480 many mailers don't support it. @xref{rfc2231}.
1488 While not really a part of the @acronym{MIME} library, it is convenient to
1489 document this library here. It deals with parsing @code{Date} headers
1490 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1493 These functions convert between five formats: A date string, an Emacs
1494 time structure, a decoded time list, a second number, and a day number.
1496 Here's a bunch of time/date/second/day examples:
1499 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1500 @result{} (54 21 12 12 9 1998 6 nil 7200)
1502 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1503 @result{} (13818 19266)
1505 (time-to-seconds '(13818 19266))
1506 @result{} 905595714.0
1508 (seconds-to-time 905595714.0)
1509 @result{} (13818 19266 0)
1511 (time-to-days '(13818 19266))
1514 (days-to-time 729644)
1515 @result{} (961933 65536)
1517 (time-since '(13818 19266))
1520 (time-less-p '(13818 19266) '(13818 19145))
1523 (subtract-time '(13818 19266) '(13818 19145))
1526 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1527 "Sat Sep 07 12:21:54 1998 +0200")
1530 (date-leap-year-p 2000)
1533 (time-to-day-in-year '(13818 19266))
1536 (time-to-number-of-days
1538 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1539 @result{} 4.146122685185185
1542 And finally, we have @code{safe-date-to-time}, which does the same as
1543 @code{date-to-time}, but returns a zero time if the date is
1544 syntactically malformed.
1546 The five data representations used are the following:
1550 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1551 12:21:54 1998 +0200"}.
1554 An internal Emacs time. For instance: @code{(13818 26466)}.
1557 A floating point representation of the internal Emacs time. For
1558 instance: @code{905595714.0}.
1561 An integer number representing the number of days since 00000101. For
1562 instance: @code{729644}.
1565 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1569 All the examples above represent the same moment.
1571 These are the functions available:
1575 Take a date and return a time.
1577 @item time-to-seconds
1578 Take a time and return seconds. Note that Emacs has a built-in
1579 function, @code{float-time}, that does this.
1581 @item seconds-to-time
1582 Take seconds and return a time.
1585 Take a time and return days.
1588 Take days and return a time.
1591 Take a date and return days.
1593 @item time-to-number-of-days
1594 Take a time and return the number of days that represents.
1596 @item safe-date-to-time
1597 Take a date and return a time. If the date is not syntactically valid,
1598 return a ``zero'' time.
1601 Take two times and say whether the first time is less (i. e., earlier)
1602 than the second time.
1605 Take a time and return a time saying how long it was since that time.
1608 Take two times and subtract the second from the first. I. e., return
1609 the time between the two times.
1612 Take two days and return the number of days between those two days.
1614 @item date-leap-year-p
1615 Take a year number and say whether it's a leap year.
1617 @item time-to-day-in-year
1618 Take a time and return the day number within the year that the time is
1627 This library deals with decoding and encoding Quoted-Printable text.
1629 Very briefly explained, qp encoding means translating all 8-bit
1630 characters (and lots of control characters) into things that look like
1631 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1634 The following functions are defined by the library:
1637 @item quoted-printable-decode-region
1638 @findex quoted-printable-decode-region
1639 QP-decode all the encoded text in the specified region.
1641 @item quoted-printable-decode-string
1642 @findex quoted-printable-decode-string
1643 Decode the QP-encoded text in a string and return the results.
1645 @item quoted-printable-encode-region
1646 @findex quoted-printable-encode-region
1647 QP-encode all the encodable characters in the specified region. The third
1648 optional parameter @var{fold} specifies whether to fold long lines.
1649 (Long here means 72.)
1651 @item quoted-printable-encode-string
1652 @findex quoted-printable-encode-string
1653 QP-encode all the encodable characters in a string and return the
1663 Base64 is an encoding that encodes three bytes into four characters,
1664 thereby increasing the size by about 33%. The alphabet used for
1665 encoding is very resistant to mangling during transit.
1667 The following functions are defined by this library:
1670 @item base64-encode-region
1671 @findex base64-encode-region
1672 base64 encode the selected region. Return the length of the encoded
1673 text. Optional third argument @var{no-line-break} means do not break
1674 long lines into shorter lines.
1676 @item base64-encode-string
1677 @findex base64-encode-string
1678 base64 encode a string and return the result.
1680 @item base64-decode-region
1681 @findex base64-decode-region
1682 base64 decode the selected region. Return the length of the decoded
1683 text. If the region can't be decoded, return @code{nil} and don't
1686 @item base64-decode-string
1687 @findex base64-decode-string
1688 base64 decode a string and return the result. If the string can't be
1689 decoded, @code{nil} is returned.
1700 @code{binhex} is an encoding that originated in Macintosh environments.
1701 The following function is supplied to deal with these:
1704 @item binhex-decode-region
1705 @findex binhex-decode-region
1706 Decode the encoded text in the region. If given a third parameter, only
1707 decode the @code{binhex} header and return the filename.
1716 @code{uuencode} is probably still the most popular encoding of binaries
1717 used on Usenet, although @code{base64} rules the mail world.
1719 The following function is supplied by this package:
1722 @item uudecode-decode-region
1723 @findex uudecode-decode-region
1724 Decode the text in the region.
1732 @code{yenc} is used for encoding binaries on Usenet. The following
1733 function is supplied by this package:
1736 @item yenc-decode-region
1737 @findex yenc-decode-region
1738 Decode the encoded text in the region.
1749 RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In
1750 essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this:
1753 This sentence is in @acronym{ASCII}.
1754 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1757 Simple enough, and widely used in China.
1759 The following functions are available to handle this encoding:
1762 @item rfc1843-decode-region
1763 Decode HZ-encoded text in the region.
1765 @item rfc1843-decode-string
1766 Decode a HZ-encoded string and return the result.
1774 The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message
1775 handlers and describes how elements are supposed to be displayed.
1776 Here's an example file:
1780 audio/wav; wavplayer %s
1781 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1784 This says that all image files should be displayed with @code{gimp},
1785 that WAVE audio files should be played by @code{wavplayer}, and that
1786 MS-WORD files should be inlined by @code{catdoc}.
1788 The @code{mailcap} library parses this file, and provides functions for
1792 @item mailcap-mime-data
1793 @vindex mailcap-mime-data
1794 This variable is an alist of alists containing backup viewing rules.
1798 Interface functions:
1801 @item mailcap-parse-mailcaps
1802 @findex mailcap-parse-mailcaps
1803 Parse the @file{~/.mailcap} file.
1805 @item mailcap-mime-info
1806 Takes a @acronym{MIME} type as its argument and returns the matching viewer.
1816 The Emacs @acronym{MIME} library implements handling of various elements
1817 according to a (somewhat) large number of RFCs, drafts and standards
1818 documents. This chapter lists the relevant ones. They can all be
1819 fetched from @uref{http://quimby.gnus.org/notes/}.
1824 Standard for the Format of ARPA Internet Text Messages.
1827 Standard for Interchange of USENET Messages
1830 Format of Internet Message Bodies
1836 Message Header Extensions for Non-@acronym{ASCII} Text
1839 Registration Procedures
1842 Conformance Criteria and Examples
1845 @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets,
1846 Languages, and Continuations
1849 HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1850 @acronym{ASCII} characters
1852 @item draft-ietf-drums-msg-fmt-05.txt
1853 Draft for the successor of RFC822
1856 The @acronym{MIME} Multipart/Related Content-type
1859 The Multipart/Report Content Type for the Reporting of Mail System
1860 Administrative Messages
1863 Communicating Presentation Information in Internet Messages: The
1864 Content-Disposition Header Field
1867 Documentation of the text/plain format parameter for flowed text.
1871 @node GNU Free Documentation License
1872 @chapter GNU Free Documentation License
1873 @include doclicense.texi
1884 @c coding: iso-8859-1