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 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 1.2 or
18 any later version published by the Free Software Foundation; with no
19 Invariant Sections, with the Front-Cover texts being ``A GNU
20 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
21 license is included in the section entitled ``GNU Free Documentation
22 License'' in the Emacs manual.
24 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
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28 This document is part of a collection distributed under the GNU Free
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31 license to the document, as described in section 6 of the license.
37 * Emacs MIME: (emacs-mime). Emacs MIME de/composition library.
42 @setchapternewpage odd
45 @title Emacs MIME Manual
47 @author by Lars Magne Ingebrigtsen
49 @vskip 0pt plus 1filll
56 This manual documents the libraries used to compose and display
57 @acronym{MIME} messages.
59 This manual is directed at users who want to modify the behavior of
60 the @acronym{MIME} encoding/decoding process or want a more detailed
61 picture of how the Emacs @acronym{MIME} library works, and people who want
62 to write functions and commands that manipulate @acronym{MIME} elements.
64 @acronym{MIME} is short for @dfn{Multipurpose Internet Mail Extensions}.
65 This standard is documented in a number of RFCs; mainly RFC2045 (Format
66 of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message
67 Header Extensions for Non-@acronym{ASCII} Text), RFC2048 (Registration
68 Procedures), RFC2049 (Conformance Criteria and Examples). It is highly
69 recommended that anyone who intends writing @acronym{MIME}-compliant software
70 read at least RFC2045 and RFC2047.
73 * Decoding and Viewing:: A framework for decoding and viewing.
74 * Composing:: @acronym{MML}; a language for describing @acronym{MIME} parts.
75 * Interface Functions:: An abstraction over the basic functions.
76 * Basic Functions:: Utility and basic parsing functions.
77 * Standards:: A summary of RFCs and working documents used.
78 * Index:: Function and variable index.
82 @node Decoding and Viewing
83 @chapter Decoding and Viewing
85 This chapter deals with decoding and viewing @acronym{MIME} messages on a
88 The main idea is to first analyze a @acronym{MIME} article, and then allow
89 other programs to do things based on the list of @dfn{handles} that are
90 returned as a result of this analysis.
93 * Dissection:: Analyzing a @acronym{MIME} message.
94 * Non-MIME:: Analyzing a non-@acronym{MIME} message.
95 * Handles:: Handle manipulations.
96 * Display:: Displaying handles.
97 * Display Customization:: Variables that affect display.
98 * Files and Directories:: Saving and naming attachments.
99 * New Viewers:: How to write your own viewers.
106 The @code{mm-dissect-buffer} is the function responsible for dissecting
107 a @acronym{MIME} article. If given a multipart message, it will recursively
108 descend the message, following the structure, and return a tree of
109 @acronym{MIME} handles that describes the structure of the message.
113 @vindex mm-uu-configure-list
115 Gnus also understands some non-@acronym{MIME} attachments, such as
116 postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp,
117 diff. Each of these features can be disabled by add an item into
118 @code{mm-uu-configure-list}. For example,
122 (add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
148 Non-@acronym{MIME} forwarded message.
156 @acronym{PGP} signed clear text.
159 @findex pgp-encrypted
160 @acronym{PGP} encrypted clear text.
164 @acronym{PGP} public keys.
167 @findex emacs-sources
168 @vindex mm-uu-emacs-sources-regexp
169 Emacs source code. This item works only in the groups matching
170 @code{mm-uu-emacs-sources-regexp}.
174 @vindex mm-uu-diff-groups-regexp
175 Patches. This is intended for groups where diffs of committed files
176 are automatically sent to. It only works in groups matching
177 @code{mm-uu-diff-groups-regexp}.
180 @cindex verbatim-marks
181 Slrn-style verbatim marks.
185 LaTeX documents. It only works in groups matching
186 @code{mm-uu-tex-groups-regexp}.
190 @cindex text/x-verbatim
191 @c Is @vindex suitable for a face?
192 @vindex mm-uu-extract
193 Some inlined non-@acronym{MIME} attachments are displayed using the face
194 @code{mm-uu-extract}. By default, no @acronym{MIME} button for these
195 parts is displayed. You can force displaying a button using @kbd{K b}
196 (@code{gnus-summary-display-buttonized}) or add @code{text/x-verbatim}
197 to @code{gnus-buttonized-mime-types}, @xref{MIME Commands, ,MIME
198 Commands, gnus, Gnus Manual}.
203 A @acronym{MIME} handle is a list that fully describes a @acronym{MIME}
206 The following macros can be used to access elements in a handle:
209 @item mm-handle-buffer
210 @findex mm-handle-buffer
211 Return the buffer that holds the contents of the undecoded @acronym{MIME}
215 @findex mm-handle-type
216 Return the parsed @code{Content-Type} of the part.
218 @item mm-handle-encoding
219 @findex mm-handle-encoding
220 Return the @code{Content-Transfer-Encoding} of the part.
222 @item mm-handle-undisplayer
223 @findex mm-handle-undisplayer
224 Return the object that can be used to remove the displayed part (if it
227 @item mm-handle-set-undisplayer
228 @findex mm-handle-set-undisplayer
229 Set the undisplayer object.
231 @item mm-handle-disposition
232 @findex mm-handle-disposition
233 Return the parsed @code{Content-Disposition} of the part.
235 @item mm-get-content-id
236 Returns the handle(s) referred to by @code{Content-ID}.
244 Functions for displaying, removing and saving.
247 @item mm-display-part
248 @findex mm-display-part
252 @findex mm-remove-part
253 Remove the part (if it has been displayed).
256 @findex mm-inlinable-p
257 Say whether a @acronym{MIME} type can be displayed inline.
259 @item mm-automatic-display-p
260 @findex mm-automatic-display-p
261 Say whether a @acronym{MIME} type should be displayed automatically.
263 @item mm-destroy-part
264 @findex mm-destroy-part
265 Free all resources occupied by a part.
269 Offer to save the part in a file.
273 Offer to pipe the part to some process.
275 @item mm-interactively-view-part
276 @findex mm-interactively-view-part
277 Prompt for a mailcap method to use to view the part.
282 @node Display Customization
283 @section Display Customization
287 @item mm-inline-media-tests
288 @vindex mm-inline-media-tests
289 This is an alist where the key is a @acronym{MIME} type, the second element
290 is a function to display the part @dfn{inline} (i.e., inside Emacs), and
291 the third element is a form to be @code{eval}ed to say whether the part
292 can be displayed inline.
294 This variable specifies whether a part @emph{can} be displayed inline,
295 and, if so, how to do it. It does not say whether parts are
296 @emph{actually} displayed inline.
298 @item mm-inlined-types
299 @vindex mm-inlined-types
300 This, on the other hand, says what types are to be displayed inline, if
301 they satisfy the conditions set by the variable above. It's a list of
302 @acronym{MIME} media types.
304 @item mm-automatic-display
305 @vindex mm-automatic-display
306 This is a list of types that are to be displayed ``automatically'', but
307 only if the above variable allows it. That is, only inlinable parts can
308 be displayed automatically.
310 @item mm-automatic-external-display
311 @vindex mm-automatic-external-display
312 This is a list of types that will be displayed automatically in an
315 @item mm-keep-viewer-alive-types
316 @vindex mm-keep-viewer-alive-types
317 This is a list of media types for which the external viewer will not
318 be killed when selecting a different article.
320 @item mm-attachment-override-types
321 @vindex mm-attachment-override-types
322 Some @acronym{MIME} agents create parts that have a content-disposition of
323 @samp{attachment}. This variable allows overriding that disposition and
324 displaying the part inline. (Note that the disposition is only
325 overridden if we are able to, and want to, display the part inline.)
327 @item mm-discouraged-alternatives
328 @vindex mm-discouraged-alternatives
329 List of @acronym{MIME} types that are discouraged when viewing
330 @samp{multipart/alternative}. Viewing agents are supposed to view the
331 last possible part of a message, as that is supposed to be the richest.
332 However, users may prefer other types instead, and this list says what
333 types are most unwanted. If, for instance, @samp{text/html} parts are
334 very unwanted, and @samp{text/richtext} parts are somewhat unwanted,
335 you could say something like:
338 (setq mm-discouraged-alternatives
339 '("text/html" "text/richtext")
341 (remove "text/html" mm-automatic-display))
344 Adding @code{"image/.*"} might also be useful. Spammers use images as
345 the preferred part of @samp{multipart/alternative} messages, so you might
346 not notice there are other parts. See also
347 @code{gnus-buttonized-mime-types}, @ref{MIME Commands, ,MIME Commands,
348 gnus, Gnus Manual}. After adding @code{"multipart/alternative"} to
349 @code{gnus-buttonized-mime-types} you can choose manually which
350 alternative you'd like to view. For example, you can set those
354 (setq gnus-buttonized-mime-types
355 '("multipart/alternative" "multipart/signed")
356 mm-discouraged-alternatives
357 '("text/html" "image/.*"))
360 In this case, Gnus will display radio buttons for such a kind of spam
364 1. (*) multipart/alternative ( ) image/gif
366 2. (*) text/plain ( ) text/html
369 @item mm-inline-large-images
370 @vindex mm-inline-large-images
371 When displaying inline images that are larger than the window, Emacs
372 does not enable scrolling, which means that you cannot see the whole
373 image. To prevent this, the library tries to determine the image size
374 before displaying it inline, and if it doesn't fit the window, the
375 library will display it externally (e.g. with @samp{ImageMagick} or
376 @samp{xv}). Setting this variable to @code{t} disables this check and
377 makes the library display all inline images as inline, regardless of
380 @item mm-inline-override-types
381 @vindex mm-inline-override-types
382 @code{mm-inlined-types} may include regular expressions, for example to
383 specify that all @samp{text/.*} parts be displayed inline. If a user
384 prefers to have a type that matches such a regular expression be treated
385 as an attachment, that can be accomplished by setting this variable to a
386 list containing that type. For example assuming @code{mm-inlined-types}
387 includes @samp{text/.*}, then including @samp{text/html} in this
388 variable will cause @samp{text/html} parts to be treated as attachments.
390 @item mm-text-html-renderer
391 @vindex mm-text-html-renderer
392 This selects the function used to render @acronym{HTML}. The predefined
393 renderers are selected by the symbols @code{w3},
394 @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
395 information about emacs-w3m}, @code{links}, @code{lynx},
396 @code{w3m-standalone} or @code{html2text}. If @code{nil} use an
397 external viewer. You can also specify a function, which will be
398 called with a @acronym{MIME} handle as the argument.
400 @item mm-inline-text-html-with-images
401 @vindex mm-inline-text-html-with-images
402 Some @acronym{HTML} mails might have the trick of spammers using
403 @samp{<img>} tags. It is likely to be intended to verify whether you
404 have read the mail. You can prevent your personal informations from
405 leaking by setting this option to @code{nil} (which is the default).
406 It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
407 command @kbd{t} on the image anchor to show an image even if it is
408 @code{nil}.@footnote{The command @kbd{T} will load all images. If you
409 have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
412 @item mm-w3m-safe-url-regexp
413 @vindex mm-w3m-safe-url-regexp
414 A regular expression that matches safe URL names, i.e. URLs that are
415 unlikely to leak personal information when rendering @acronym{HTML}
416 email (the default value is @samp{\\`cid:}). If @code{nil} consider
419 @item mm-inline-text-html-with-w3m-keymap
420 @vindex mm-inline-text-html-with-w3m-keymap
421 You can use emacs-w3m command keys in the inlined text/html part by
422 setting this option to non-@code{nil}. The default value is @code{t}.
424 @item mm-external-terminal-program
425 @vindex mm-external-terminal-program
426 The program used to start an external terminal.
428 @item mm-enable-external
429 @vindex mm-enable-external
430 Indicate whether external @acronym{MIME} handlers should be used.
432 If @code{t}, all defined external @acronym{MIME} handlers are used. If
433 @code{nil}, files are saved to disk (@code{mailcap-save-binary-file}).
434 If it is the symbol @code{ask}, you are prompted before the external
435 @acronym{MIME} handler is invoked.
437 When you launch an attachment through mailcap (@pxref{mailcap}) an
438 attempt is made to use a safe viewer with the safest options---this isn't
439 the case if you save it to disk and launch it in a different way
440 (command line or double-clicking). Anyhow, if you want to be sure not
441 to launch any external programs, set this variable to @code{nil} or
446 @node Files and Directories
447 @section Files and Directories
451 @item mm-default-directory
452 @vindex mm-default-directory
453 The default directory for saving attachments. If @code{nil} use
454 @code{default-directory}.
456 @item mm-tmp-directory
457 @vindex mm-tmp-directory
458 Directory for storing temporary files.
460 @item mm-file-name-rewrite-functions
461 @vindex mm-file-name-rewrite-functions
462 A list of functions used for rewriting file names of @acronym{MIME}
463 parts. Each function is applied successively to the file name.
464 Ready-made functions include
467 @item mm-file-name-delete-control
468 @findex mm-file-name-delete-control
469 Delete all control characters.
471 @item mm-file-name-delete-gotchas
472 @findex mm-file-name-delete-gotchas
473 Delete characters that could have unintended consequences when used
474 with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and
475 @samp{-}, @samp{.} as the first character.
477 @item mm-file-name-delete-whitespace
478 @findex mm-file-name-delete-whitespace
479 Remove all whitespace.
481 @item mm-file-name-trim-whitespace
482 @findex mm-file-name-trim-whitespace
483 Remove leading and trailing whitespace.
485 @item mm-file-name-collapse-whitespace
486 @findex mm-file-name-collapse-whitespace
487 Collapse multiple whitespace characters.
489 @item mm-file-name-replace-whitespace
490 @findex mm-file-name-replace-whitespace
491 @vindex mm-file-name-replace-whitespace
492 Replace whitespace with underscores. Set the variable
493 @code{mm-file-name-replace-whitespace} to any other string if you do
494 not like underscores.
497 The standard Emacs functions @code{capitalize}, @code{downcase},
498 @code{upcase} and @code{upcase-initials} might also prove useful.
500 @item mm-path-name-rewrite-functions
501 @vindex mm-path-name-rewrite-functions
502 List of functions used for rewriting the full file names of @acronym{MIME}
503 parts. This is used when viewing parts externally, and is meant for
504 transforming the absolute name so that non-compliant programs can find
505 the file where it's saved.
512 Here's an example viewer for displaying @code{text/enriched} inline:
515 (defun mm-display-enriched-inline (handle)
518 (mm-insert-part handle)
519 (save-window-excursion
520 (enriched-decode (point-min) (point-max))
521 (setq text (buffer-string))))
522 (mm-insert-inline handle text)))
525 We see that the function takes a @acronym{MIME} handle as its parameter. It
526 then goes to a temporary buffer, inserts the text of the part, does some
527 work on the text, stores the result, goes back to the buffer it was
528 called from and inserts the result.
530 The two important helper functions here are @code{mm-insert-part} and
531 @code{mm-insert-inline}. The first function inserts the text of the
532 handle in the current buffer. It handles charset and/or content
533 transfer decoding. The second function just inserts whatever text you
534 tell it to insert, but it also sets things up so that the text can be
535 ``undisplayed'' in a convenient manner.
541 @cindex MIME Composing
543 @cindex MIME Meta Language
545 Creating a @acronym{MIME} message is boring and non-trivial. Therefore,
546 a library called @code{mml} has been defined that parses a language
547 called @acronym{MML} (@acronym{MIME} Meta Language) and generates
548 @acronym{MIME} messages.
550 @findex mml-generate-mime
551 The main interface function is @code{mml-generate-mime}. It will
552 examine the contents of the current (narrowed-to) buffer and return a
553 string containing the @acronym{MIME} message.
556 * Simple MML Example:: An example @acronym{MML} document.
557 * MML Definition:: All valid @acronym{MML} elements.
558 * Advanced MML Example:: Another example @acronym{MML} document.
559 * Encoding Customization:: Variables that affect encoding.
560 * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}.
561 * Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa.
562 * Flowed text:: Soft and hard newlines.
566 @node Simple MML Example
567 @section Simple MML Example
569 Here's a simple @samp{multipart/alternative}:
572 <#multipart type=alternative>
573 This is a plain text part.
574 <#part type=text/enriched>
575 <center>This is a centered enriched part</center>
579 After running this through @code{mml-generate-mime}, we get this:
582 Content-Type: multipart/alternative; boundary="=-=-="
588 This is a plain text part.
591 Content-Type: text/enriched
594 <center>This is a centered enriched part</center>
601 @section MML Definition
603 The @acronym{MML} language is very simple. It looks a bit like an SGML
604 application, but it's not.
606 The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a
607 different type or use a different charset. The way to delineate a part
608 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
609 with the @samp{<#multipart ...>} tag. Parts are ended by the
610 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
611 @samp{<#part ...>} tags are also closed by the next open tag.
613 There's also the @samp{<#external ...>} tag. These introduce
614 @samp{external/message-body} parts.
616 Each tag can contain zero or more parameters on the form
617 @samp{parameter=value}. The values may be enclosed in quotation marks,
618 but that's not necessary unless the value contains white space. So
619 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
621 The following parameters have meaning in @acronym{MML}; parameters that have no
622 meaning are ignored. The @acronym{MML} parameter names are the same as the
623 @acronym{MIME} parameter names; the things in the parentheses say which
624 header it will be used in.
628 The @acronym{MIME} type of the part (@code{Content-Type}).
631 Use the contents of the file in the body of the part
632 (@code{Content-Disposition}).
635 The contents of the body of the part are to be encoded in the character
636 set specified (@code{Content-Type}). @xref{Charset Translation}.
639 Might be used to suggest a file name if the part is to be saved
640 to a file (@code{Content-Type}).
643 Valid values are @samp{inline} and @samp{attachment}
644 (@code{Content-Disposition}).
647 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
648 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
652 A description of the part (@code{Content-Description}).
655 RFC822 date when the part was created (@code{Content-Disposition}).
657 @item modification-date
658 RFC822 date when the part was modified (@code{Content-Disposition}).
661 RFC822 date when the part was read (@code{Content-Disposition}).
664 Who to encrypt/sign the part to. This field is used to override any
665 auto-detection based on the To/CC headers.
668 Identity used to sign the part. This field is used to override the
672 The size (in octets) of the part (@code{Content-Disposition}).
675 What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp}
679 What technology to encrypt this @acronym{MML} part with (@code{smime},
680 @code{pgp} or @code{pgpmime})
684 Parameters for @samp{text/plain}:
688 Formatting parameter for the text, valid values include @samp{fixed}
689 (the default) and @samp{flowed}. Normally you do not specify this
690 manually, since it requires the textual body to be formatted in a
691 special way described in RFC 2646. @xref{Flowed text}.
694 Parameters for @samp{application/octet-stream}:
698 Type of the part; informal---meant for human readers
699 (@code{Content-Type}).
702 Parameters for @samp{message/external-body}:
706 A word indicating the supported access mechanism by which the file may
707 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
708 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
711 The RFC822 date after which the file may no longer be fetched.
712 (@code{Content-Type}.)
715 The size (in octets) of the file. (@code{Content-Type}.)
718 Valid values are @samp{read} and @samp{read-write}
719 (@code{Content-Type}).
723 Parameters for @samp{sign=smime}:
728 File containing key and certificate for signer.
732 Parameters for @samp{encrypt=smime}:
737 File containing certificate for recipient.
742 @node Advanced MML Example
743 @section Advanced MML Example
745 Here's a complex multipart message. It's a @samp{multipart/mixed} that
746 contains many parts, one of which is a @samp{multipart/alternative}.
749 <#multipart type=mixed>
750 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
751 <#multipart type=alternative>
752 This is a plain text part.
753 <#part type=text/enriched name=enriched.txt>
754 <center>This is a centered enriched part</center>
756 This is a new plain text part.
757 <#part disposition=attachment>
758 This plain text part is an attachment.
762 And this is the resulting @acronym{MIME} message:
765 Content-Type: multipart/mixed; boundary="=-=-="
773 Content-Type: image/jpeg;
775 Content-Disposition: inline;
777 Content-Transfer-Encoding: base64
779 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
780 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
781 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
782 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
783 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
784 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
785 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
786 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
787 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
788 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
789 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
790 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
791 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
792 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
793 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
794 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
795 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
798 Content-Type: multipart/alternative; boundary="==-=-="
804 This is a plain text part.
807 Content-Type: text/enriched;
811 <center>This is a centered enriched part</center>
817 This is a new plain text part.
820 Content-Disposition: attachment
823 This plain text part is an attachment.
828 @node Encoding Customization
829 @section Encoding Customization
833 @item mm-body-charset-encoding-alist
834 @vindex mm-body-charset-encoding-alist
835 Mapping from @acronym{MIME} charset to encoding to use. This variable is
836 usually used except, e.g., when other requirements force a specific
837 encoding (digitally signed messages require 7bit encodings). The
841 ((iso-2022-jp . 7bit)
842 (iso-2022-jp-2 . 7bit)
848 As an example, if you do not want to have ISO-8859-1 characters
849 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
850 this variable. You can override this setting on a per-message basis
851 by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
853 @item mm-coding-system-priorities
854 @vindex mm-coding-system-priorities
855 Prioritize coding systems to use for outgoing messages. The default
856 is @code{nil}, which means to use the defaults in Emacs, but is
857 @code{(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)} when
858 running Emacs in the Japanese language environment. It is a list of
859 coding system symbols (aliases of coding systems are also allowed, use
860 @kbd{M-x describe-coding-system} to make sure you are specifying correct
861 coding system names). For example, if you have configured Emacs
862 to prefer UTF-8, but wish that outgoing messages should be sent in
863 ISO-8859-1 if possible, you can set this variable to
864 @code{(iso-8859-1)}. You can override this setting on a per-message
865 basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}).
867 As different hierarchies prefer different charsets, you may want to set
868 @code{mm-coding-system-priorities} according to the hierarchy in Gnus.
871 @c Corrections about preferred charsets are welcome. de, fr and fj
872 @c should be correct, I don't know about the rest (so these are only
875 (add-to-list 'gnus-newsgroup-variables 'mm-coding-system-priorities)
876 (setq gnus-parameters
878 ;; Some charsets are just examples!
879 '(("^cn\\." ;; Chinese
880 (mm-coding-system-priorities
881 '(iso-8859-1 cn-big5 chinese-iso-7bit utf-8)))
882 ("^cz\\.\\|^pl\\." ;; Central and Eastern European
883 (mm-coding-system-priorities '(iso-8859-2 utf-8)))
884 ("^de\\." ;; German language
885 (mm-coding-system-priorities '(iso-8859-1 iso-8859-15 utf-8)))
887 (mm-coding-system-priorities '(iso-8859-15 iso-8859-1 utf-8)))
888 ("^fj\\." ;; Japanese
889 (mm-coding-system-priorities
890 '(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)))
891 ("^ru\\." ;; Cyrillic
892 (mm-coding-system-priorities
893 '(koi8-r iso-8859-5 iso-8859-1 utf-8))))
897 @item mm-content-transfer-encoding-defaults
898 @vindex mm-content-transfer-encoding-defaults
899 Mapping from @acronym{MIME} types to encoding to use. This variable is usually
900 used except, e.g., when other requirements force a safer encoding
901 (digitally signed messages require 7bit encoding). Besides the normal
902 @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
903 each case the most efficient of quoted-printable and base64 should be
906 @code{qp-or-base64} has another effect. It will fold long lines so that
907 MIME parts may not be broken by MTA. So do @code{quoted-printable} and
910 Note that it affects body encoding only when a part is a raw forwarded
911 message (which will be made by @code{gnus-summary-mail-forward} with the
912 arg 2 for example) or is neither the @samp{text/*} type nor the
913 @samp{message/*} type. Even though in those cases, you can override
914 this setting on a per-message basis by using the @code{encoding}
915 @acronym{MML} tag (@pxref{MML Definition}).
917 @item mm-use-ultra-safe-encoding
918 @vindex mm-use-ultra-safe-encoding
919 When this is non-@code{nil}, it means that textual parts are encoded as
920 quoted-printable if they contain lines longer than 76 characters or
921 starting with "From " in the body. Non-7bit encodings (8bit, binary)
922 are generally disallowed. This reduce the probability that a non-8bit
923 clean MTA or MDA changes the message. This should never be set
924 directly, but bound by other functions when necessary (e.g., when
925 encoding messages that are to be digitally signed).
929 @node Charset Translation
930 @section Charset Translation
933 During translation from @acronym{MML} to @acronym{MIME}, for each
934 @acronym{MIME} part which has been composed inside Emacs, an appropriate
935 charset has to be chosen.
937 @vindex mail-parse-charset
938 If you are running a non-@sc{mule} Emacs, this process is simple: If the
939 part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset
940 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
941 variable directly, though. If you want to change the default charset,
942 please consult the documentation of the package which you use to process
943 @acronym{MIME} messages.
944 @xref{Various Message Variables, , Various Message Variables, message,
945 Message Manual}, for example.)
946 If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is
952 @vindex mm-mime-mule-charset-alist
953 Things are slightly more complicated when running Emacs with @sc{mule}
954 support. In this case, a list of the @sc{mule} charsets used in the
955 part is obtained, and the @sc{mule} charsets are translated to
956 @acronym{MIME} charsets by consulting the table provided by Emacs itself
957 or the variable @code{mm-mime-mule-charset-alist} for XEmacs.
958 If this results in a single @acronym{MIME} charset, this is used to encode
959 the part. But if the resulting list of @acronym{MIME} charsets contains more
960 than one element, two things can happen: If it is possible to encode the
961 part via UTF-8, this charset is used. (For this, Emacs must support
962 the @code{utf-8} coding system, and the part must consist entirely of
963 characters which have Unicode counterparts.) If UTF-8 is not available
964 for some reason, the part is split into several ones, so that each one
965 can be encoded with a single @acronym{MIME} charset. The part can only be
966 split at line boundaries, though---if more than one @acronym{MIME} charset is
967 required to encode a single line, it is not possible to encode the part.
969 When running Emacs with @sc{mule} support, the preferences for which
970 coding system to use is inherited from Emacs itself. This means that
971 if Emacs is set up to prefer UTF-8, it will be used when encoding
972 messages. You can modify this by altering the
973 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
976 The charset to be used can be overridden by setting the @code{charset}
977 @acronym{MML} tag (@pxref{MML Definition}) when composing the message.
979 The encoding of characters (quoted-printable, 8bit etc) is orthogonal
980 to the discussion here, and is controlled by the variables
981 @code{mm-body-charset-encoding-alist} and
982 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
989 A (multipart) @acronym{MIME} message can be converted to @acronym{MML}
990 with the @code{mime-to-mml} function. It works on the message in the
991 current buffer, and substitutes @acronym{MML} markup for @acronym{MIME}
992 boundaries. Non-textual parts do not have their contents in the buffer,
993 but instead have the contents in separate buffers that are referred to
994 from the @acronym{MML} tags.
997 An @acronym{MML} message can be converted back to @acronym{MIME} by the
998 @code{mml-to-mime} function.
1000 These functions are in certain senses ``lossy''---you will not get back
1001 an identical message if you run @code{mime-to-mml} and then
1002 @code{mml-to-mime}. Not only will trivial things like the order of the
1003 headers differ, but the contents of the headers may also be different.
1004 For instance, the original message may use base64 encoding on text,
1005 while @code{mml-to-mime} may decide to use quoted-printable encoding, and
1008 In essence, however, these two functions should be the inverse of each
1009 other. The resulting contents of the message should remain equivalent,
1014 @section Flowed text
1015 @cindex format=flowed
1017 The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines}
1018 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
1019 emacs, Emacs Manual}) when encoding a message, and the
1020 ``format=flowed'' Content-Type parameter when decoding a message.
1022 On encoding text, regardless of @code{use-hard-newlines}, lines
1023 terminated by soft newline characters are filled together and wrapped
1024 after the column decided by @code{fill-flowed-encode-column}.
1025 Quotation marks (matching @samp{^>* ?}) are respected. The variable
1026 controls how the text will look in a client that does not support
1027 flowed text, the default is to wrap after 66 characters. If hard
1028 newline characters are not present in the buffer, no flow encoding
1031 On decoding flowed text, lines with soft newline characters are filled
1032 together and wrapped after the column decided by
1033 @code{fill-flowed-display-column}. The default is to wrap after
1037 @item mm-fill-flowed
1038 @vindex mm-fill-flowed
1039 If non-@code{nil} a format=flowed article will be displayed flowed.
1043 @node Interface Functions
1044 @chapter Interface Functions
1045 @cindex interface functions
1048 The @code{mail-parse} library is an abstraction over the actual
1049 low-level libraries that are described in the next chapter.
1051 Standards change, and so programs have to change to fit in the new
1052 mold. For instance, RFC2045 describes a syntax for the
1053 @code{Content-Type} header that only allows @acronym{ASCII} characters in the
1054 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
1055 for continuation headers and non-@acronym{ASCII} characters.
1057 The traditional way to deal with this is just to update the library
1058 functions to parse the new syntax. However, this is sometimes the wrong
1059 thing to do. In some instances it may be vital to be able to understand
1060 both the old syntax as well as the new syntax, and if there is only one
1061 library, one must choose between the old version of the library and the
1062 new version of the library.
1064 The Emacs @acronym{MIME} library takes a different tack. It defines a
1065 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
1066 and so on) that parses strictly according to the corresponding
1067 standard. However, normal programs would not use the functions
1068 provided by these libraries directly, but instead use the functions
1069 provided by the @code{mail-parse} library. The functions in this
1070 library are just aliases to the corresponding functions in the latest
1071 low-level libraries. Using this scheme, programs get a consistent
1072 interface they can use, and library developers are free to create
1073 write code that handles new standards.
1075 The following functions are defined by this library:
1078 @item mail-header-parse-content-type
1079 @findex mail-header-parse-content-type
1080 Parse a @code{Content-Type} header and return a list on the following
1085 (attribute1 . value1)
1086 (attribute2 . value2)
1093 (mail-header-parse-content-type
1094 "image/gif; name=\"b980912.gif\"")
1095 @result{} ("image/gif" (name . "b980912.gif"))
1098 @item mail-header-parse-content-disposition
1099 @findex mail-header-parse-content-disposition
1100 Parse a @code{Content-Disposition} header and return a list on the same
1101 format as the function above.
1103 @item mail-content-type-get
1104 @findex mail-content-type-get
1105 Takes two parameters---a list on the format above, and an attribute.
1106 Returns the value of the attribute.
1109 (mail-content-type-get
1110 '("image/gif" (name . "b980912.gif")) 'name)
1111 @result{} "b980912.gif"
1114 @item mail-header-encode-parameter
1115 @findex mail-header-encode-parameter
1116 Takes a parameter string and returns an encoded version of the string.
1117 This is used for parameters in headers like @code{Content-Type} and
1118 @code{Content-Disposition}.
1120 @item mail-header-remove-comments
1121 @findex mail-header-remove-comments
1122 Return a comment-free version of a header.
1125 (mail-header-remove-comments
1126 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1127 @result{} "Gnus/5.070027 "
1130 @item mail-header-remove-whitespace
1131 @findex mail-header-remove-whitespace
1132 Remove linear white space from a header. Space inside quoted strings
1133 and comments is preserved.
1136 (mail-header-remove-whitespace
1137 "image/gif; name=\"Name with spaces\"")
1138 @result{} "image/gif;name=\"Name with spaces\""
1141 @item mail-header-get-comment
1142 @findex mail-header-get-comment
1143 Return the last comment in a header.
1146 (mail-header-get-comment
1147 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1148 @result{} "Finnish Landrace"
1151 @item mail-header-parse-address
1152 @findex mail-header-parse-address
1153 Parse an address and return a list containing the mailbox and the
1157 (mail-header-parse-address
1158 "Hrvoje Niksic <hniksic@@srce.hr>")
1159 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1162 @item mail-header-parse-addresses
1163 @findex mail-header-parse-addresses
1164 Parse a string with list of addresses and return a list of elements like
1165 the one described above.
1168 (mail-header-parse-addresses
1169 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1170 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1171 ("sb@@metis.no" . "Steinar Bang"))
1174 @item mail-header-parse-date
1175 @findex mail-header-parse-date
1176 Parse a date string and return an Emacs time structure.
1178 @item mail-narrow-to-head
1179 @findex mail-narrow-to-head
1180 Narrow the buffer to the header section of the buffer. Point is placed
1181 at the beginning of the narrowed buffer.
1183 @item mail-header-narrow-to-field
1184 @findex mail-header-narrow-to-field
1185 Narrow the buffer to the header under point. Understands continuation
1188 @item mail-header-fold-field
1189 @findex mail-header-fold-field
1190 Fold the header under point.
1192 @item mail-header-unfold-field
1193 @findex mail-header-unfold-field
1194 Unfold the header under point.
1196 @item mail-header-field-value
1197 @findex mail-header-field-value
1198 Return the value of the field under point.
1200 @item mail-encode-encoded-word-region
1201 @findex mail-encode-encoded-word-region
1202 Encode the non-@acronym{ASCII} words in the region. For instance,
1203 @samp{Na@"{@dotless{i}}ve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1205 @item mail-encode-encoded-word-buffer
1206 @findex mail-encode-encoded-word-buffer
1207 Encode the non-@acronym{ASCII} words in the current buffer. This function is
1208 meant to be called narrowed to the headers of a message.
1210 @item mail-encode-encoded-word-string
1211 @findex mail-encode-encoded-word-string
1212 Encode the words that need encoding in a string, and return the result.
1215 (mail-encode-encoded-word-string
1216 "This is na@"{@dotless{i}}ve, baby")
1217 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1220 @item mail-decode-encoded-word-region
1221 @findex mail-decode-encoded-word-region
1222 Decode the encoded words in the region.
1224 @item mail-decode-encoded-word-string
1225 @findex mail-decode-encoded-word-string
1226 Decode the encoded words in the string and return the result.
1229 (mail-decode-encoded-word-string
1230 "This is =?iso-8859-1?q?na=EFve,?= baby")
1231 @result{} "This is na@"{@dotless{i}}ve, baby"
1236 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1237 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1238 in the subsequent sections.
1242 @node Basic Functions
1243 @chapter Basic Functions
1245 This chapter describes the basic, ground-level functions for parsing and
1246 handling. Covered here is parsing @code{From} lines, removing comments
1247 from header lines, decoding encoded words, parsing date headers and so
1248 on. High-level functionality is dealt with in the first chapter
1249 (@pxref{Decoding and Viewing}).
1252 * rfc2045:: Encoding @code{Content-Type} headers.
1253 * rfc2231:: Parsing @code{Content-Type} headers.
1254 * ietf-drums:: Handling mail headers defined by RFC822bis.
1255 * rfc2047:: En/decoding encoded words in headers.
1256 * time-date:: Functions for parsing dates and manipulating time.
1257 * qp:: Quoted-Printable en/decoding.
1258 * base64:: Base64 en/decoding.
1259 * binhex:: Binhex decoding.
1260 * uudecode:: Uuencode decoding.
1261 * yenc:: Yenc decoding.
1262 * rfc1843:: Decoding HZ-encoded text.
1263 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1270 RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would
1271 imagine that there would be a lot to implement. But there isn't, since
1272 most of the implementation details are delegated to the subsequent
1275 So @file{rfc2045.el} has only a single function:
1278 @item rfc2045-encode-string
1279 @findex rfc2045-encode-string
1280 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1281 @var{value} will be quoted if there are non-safe characters in it.
1288 RFC2231 defines a syntax for the @code{Content-Type} and
1289 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1290 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1293 In short, these headers look something like this:
1296 Content-Type: application/x-stuff;
1297 title*0*=us-ascii'en'This%20is%20even%20more%20;
1298 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1302 They usually aren't this bad, though.
1304 The following functions are defined by this library:
1307 @item rfc2231-parse-string
1308 @findex rfc2231-parse-string
1309 Parse a @code{Content-Type} header and return a list describing its
1313 (rfc2231-parse-string
1314 "application/x-stuff;
1315 title*0*=us-ascii'en'This%20is%20even%20more%20;
1316 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1317 title*2=\"isn't it!\"")
1318 @result{} ("application/x-stuff"
1319 (title . "This is even more ***fun*** isn't it!"))
1322 @item rfc2231-get-value
1323 @findex rfc2231-get-value
1324 Takes one of the lists on the format above and returns
1325 the value of the specified attribute.
1327 @item rfc2231-encode-string
1328 @findex rfc2231-encode-string
1329 Encode a parameter in headers likes @code{Content-Type} and
1330 @code{Content-Disposition}.
1338 @dfn{drums} is an IETF working group that is working on the replacement
1341 The functions provided by this library include:
1344 @item ietf-drums-remove-comments
1345 @findex ietf-drums-remove-comments
1346 Remove the comments from the argument and return the results.
1348 @item ietf-drums-remove-whitespace
1349 @findex ietf-drums-remove-whitespace
1350 Remove linear white space from the string and return the results.
1351 Spaces inside quoted strings and comments are left untouched.
1353 @item ietf-drums-get-comment
1354 @findex ietf-drums-get-comment
1355 Return the last most comment from the string.
1357 @item ietf-drums-parse-address
1358 @findex ietf-drums-parse-address
1359 Parse an address string and return a list that contains the mailbox and
1360 the plain text name.
1362 @item ietf-drums-parse-addresses
1363 @findex ietf-drums-parse-addresses
1364 Parse a string that contains any number of comma-separated addresses and
1365 return a list that contains mailbox/plain text pairs.
1367 @item ietf-drums-parse-date
1368 @findex ietf-drums-parse-date
1369 Parse a date string and return an Emacs time structure.
1371 @item ietf-drums-narrow-to-header
1372 @findex ietf-drums-narrow-to-header
1373 Narrow the buffer to the header section of the current buffer.
1381 RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how
1382 non-@acronym{ASCII} text in headers are to be encoded. This is actually rather
1383 complicated, so a number of variables are necessary to tweak what this
1386 The following variables are tweakable:
1389 @item rfc2047-header-encoding-alist
1390 @vindex rfc2047-header-encoding-alist
1391 This is an alist of header / encoding-type pairs. Its main purpose is
1392 to prevent encoding of certain headers.
1394 The keys can either be header regexps, or @code{t}.
1396 The values can be @code{nil}, in which case the header(s) in question
1397 won't be encoded, @code{mime}, which means that they will be encoded, or
1398 @code{address-mime}, which means the header(s) will be encoded carefully
1399 assuming they contain addresses.
1401 @item rfc2047-charset-encoding-alist
1402 @vindex rfc2047-charset-encoding-alist
1403 RFC2047 specifies two forms of encoding---@code{Q} (a
1404 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1405 specifies which charset should use which encoding.
1407 @item rfc2047-encode-function-alist
1408 @vindex rfc2047-encode-function-alist
1409 This is an alist of encoding / function pairs. The encodings are
1410 @code{Q}, @code{B} and @code{nil}.
1412 @item rfc2047-encoded-word-regexp
1413 @vindex rfc2047-encoded-word-regexp
1414 When decoding words, this library looks for matches to this regexp.
1416 @item rfc2047-encode-encoded-words
1417 @vindex rfc2047-encode-encoded-words
1418 The boolean variable specifies whether encoded words
1419 (e.g. @samp{=?hello?=}) should be encoded again.
1423 Those were the variables, and these are this functions:
1426 @item rfc2047-narrow-to-field
1427 @findex rfc2047-narrow-to-field
1428 Narrow the buffer to the header on the current line.
1430 @item rfc2047-encode-message-header
1431 @findex rfc2047-encode-message-header
1432 Should be called narrowed to the header of a message. Encodes according
1433 to @code{rfc2047-header-encoding-alist}.
1435 @item rfc2047-encode-region
1436 @findex rfc2047-encode-region
1437 Encodes all encodable words in the region specified.
1439 @item rfc2047-encode-string
1440 @findex rfc2047-encode-string
1441 Encode a string and return the results.
1443 @item rfc2047-decode-region
1444 @findex rfc2047-decode-region
1445 Decode the encoded words in the region.
1447 @item rfc2047-decode-string
1448 @findex rfc2047-decode-string
1449 Decode a string and return the results.
1451 @item rfc2047-encode-parameter
1452 @findex rfc2047-encode-parameter
1453 Encode a parameter in the RFC2047-like style. This is a replacement for
1454 the @code{rfc2231-encode-string} function. @xref{rfc2231}.
1456 When attaching files as @acronym{MIME} parts, we should use the RFC2231
1457 encoding to specify the file names containing non-@acronym{ASCII}
1458 characters. However, many mail softwares don't support it in practice
1459 and recipients won't be able to extract files with correct names.
1460 Instead, the RFC2047-like encoding is acceptable generally. This
1461 function provides the very RFC2047-like encoding, resigning to such a
1462 regrettable trend. To use it, put the following line in your
1463 @file{~/.gnus.el} file:
1466 (defalias 'mail-header-encode-parameter 'rfc2047-encode-parameter)
1475 While not really a part of the @acronym{MIME} library, it is convenient to
1476 document this library here. It deals with parsing @code{Date} headers
1477 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1480 These functions convert between five formats: A date string, an Emacs
1481 time structure, a decoded time list, a second number, and a day number.
1483 Here's a bunch of time/date/second/day examples:
1486 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1487 @result{} (54 21 12 12 9 1998 6 nil 7200)
1489 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1490 @result{} (13818 19266)
1492 (time-to-seconds '(13818 19266))
1493 @result{} 905595714.0
1495 (seconds-to-time 905595714.0)
1496 @result{} (13818 19266 0)
1498 (time-to-days '(13818 19266))
1501 (days-to-time 729644)
1502 @result{} (961933 65536)
1504 (time-since '(13818 19266))
1507 (time-less-p '(13818 19266) '(13818 19145))
1510 (subtract-time '(13818 19266) '(13818 19145))
1513 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1514 "Sat Sep 07 12:21:54 1998 +0200")
1517 (date-leap-year-p 2000)
1520 (time-to-day-in-year '(13818 19266))
1523 (time-to-number-of-days
1525 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1526 @result{} 4.146122685185185
1529 And finally, we have @code{safe-date-to-time}, which does the same as
1530 @code{date-to-time}, but returns a zero time if the date is
1531 syntactically malformed.
1533 The five data representations used are the following:
1537 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1538 12:21:54 1998 +0200"}.
1541 An internal Emacs time. For instance: @code{(13818 26466)}.
1544 A floating point representation of the internal Emacs time. For
1545 instance: @code{905595714.0}.
1548 An integer number representing the number of days since 00000101. For
1549 instance: @code{729644}.
1552 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1556 All the examples above represent the same moment.
1558 These are the functions available:
1562 Take a date and return a time.
1564 @item time-to-seconds
1565 Take a time and return seconds.
1567 @item seconds-to-time
1568 Take seconds and return a time.
1571 Take a time and return days.
1574 Take days and return a time.
1577 Take a date and return days.
1579 @item time-to-number-of-days
1580 Take a time and return the number of days that represents.
1582 @item safe-date-to-time
1583 Take a date and return a time. If the date is not syntactically valid,
1584 return a ``zero'' time.
1587 Take two times and say whether the first time is less (i. e., earlier)
1588 than the second time.
1591 Take a time and return a time saying how long it was since that time.
1594 Take two times and subtract the second from the first. I. e., return
1595 the time between the two times.
1598 Take two days and return the number of days between those two days.
1600 @item date-leap-year-p
1601 Take a year number and say whether it's a leap year.
1603 @item time-to-day-in-year
1604 Take a time and return the day number within the year that the time is
1613 This library deals with decoding and encoding Quoted-Printable text.
1615 Very briefly explained, qp encoding means translating all 8-bit
1616 characters (and lots of control characters) into things that look like
1617 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1620 The following functions are defined by the library:
1623 @item quoted-printable-decode-region
1624 @findex quoted-printable-decode-region
1625 QP-decode all the encoded text in the specified region.
1627 @item quoted-printable-decode-string
1628 @findex quoted-printable-decode-string
1629 Decode the QP-encoded text in a string and return the results.
1631 @item quoted-printable-encode-region
1632 @findex quoted-printable-encode-region
1633 QP-encode all the encodable characters in the specified region. The third
1634 optional parameter @var{fold} specifies whether to fold long lines.
1635 (Long here means 72.)
1637 @item quoted-printable-encode-string
1638 @findex quoted-printable-encode-string
1639 QP-encode all the encodable characters in a string and return the
1649 Base64 is an encoding that encodes three bytes into four characters,
1650 thereby increasing the size by about 33%. The alphabet used for
1651 encoding is very resistant to mangling during transit.
1653 The following functions are defined by this library:
1656 @item base64-encode-region
1657 @findex base64-encode-region
1658 base64 encode the selected region. Return the length of the encoded
1659 text. Optional third argument @var{no-line-break} means do not break
1660 long lines into shorter lines.
1662 @item base64-encode-string
1663 @findex base64-encode-string
1664 base64 encode a string and return the result.
1666 @item base64-decode-region
1667 @findex base64-decode-region
1668 base64 decode the selected region. Return the length of the decoded
1669 text. If the region can't be decoded, return @code{nil} and don't
1672 @item base64-decode-string
1673 @findex base64-decode-string
1674 base64 decode a string and return the result. If the string can't be
1675 decoded, @code{nil} is returned.
1686 @code{binhex} is an encoding that originated in Macintosh environments.
1687 The following function is supplied to deal with these:
1690 @item binhex-decode-region
1691 @findex binhex-decode-region
1692 Decode the encoded text in the region. If given a third parameter, only
1693 decode the @code{binhex} header and return the filename.
1702 @code{uuencode} is probably still the most popular encoding of binaries
1703 used on Usenet, although @code{base64} rules the mail world.
1705 The following function is supplied by this package:
1708 @item uudecode-decode-region
1709 @findex uudecode-decode-region
1710 Decode the text in the region.
1718 @code{yenc} is used for encoding binaries on Usenet. The following
1719 function is supplied by this package:
1722 @item yenc-decode-region
1723 @findex yenc-decode-region
1724 Decode the encoded text in the region.
1735 RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In
1736 essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this:
1739 This sentence is in @acronym{ASCII}.
1740 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1743 Simple enough, and widely used in China.
1745 The following functions are available to handle this encoding:
1748 @item rfc1843-decode-region
1749 Decode HZ-encoded text in the region.
1751 @item rfc1843-decode-string
1752 Decode a HZ-encoded string and return the result.
1760 The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message
1761 handlers and describes how elements are supposed to be displayed.
1762 Here's an example file:
1766 audio/wav; wavplayer %s
1767 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1770 This says that all image files should be displayed with @code{gimp},
1771 that WAVE audio files should be played by @code{wavplayer}, and that
1772 MS-WORD files should be inlined by @code{catdoc}.
1774 The @code{mailcap} library parses this file, and provides functions for
1778 @item mailcap-mime-data
1779 @vindex mailcap-mime-data
1780 This variable is an alist of alists containing backup viewing rules.
1784 Interface functions:
1787 @item mailcap-parse-mailcaps
1788 @findex mailcap-parse-mailcaps
1789 Parse the @file{~/.mailcap} file.
1791 @item mailcap-mime-info
1792 Takes a @acronym{MIME} type as its argument and returns the matching viewer.
1802 The Emacs @acronym{MIME} library implements handling of various elements
1803 according to a (somewhat) large number of RFCs, drafts and standards
1804 documents. This chapter lists the relevant ones. They can all be
1805 fetched from @uref{http://quimby.gnus.org/notes/}.
1810 Standard for the Format of ARPA Internet Text Messages.
1813 Standard for Interchange of USENET Messages
1816 Format of Internet Message Bodies
1822 Message Header Extensions for Non-@acronym{ASCII} Text
1825 Registration Procedures
1828 Conformance Criteria and Examples
1831 @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets,
1832 Languages, and Continuations
1835 HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1836 @acronym{ASCII} characters
1838 @item draft-ietf-drums-msg-fmt-05.txt
1839 Draft for the successor of RFC822
1842 The @acronym{MIME} Multipart/Related Content-type
1845 The Multipart/Report Content Type for the Reporting of Mail System
1846 Administrative Messages
1849 Communicating Presentation Information in Internet Messages: The
1850 Content-Disposition Header Field
1853 Documentation of the text/plain format parameter for flowed text.
1869 @c coding: iso-8859-1
1873 arch-tag: c7ef2fd0-a91c-4e10-aa52-c1a2b11b1a8d