3 @setfilename emacs-mime
4 @settitle Emacs MIME Manual
10 This file documents the Emacs MIME interface functionality.
12 Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
13 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
25 this GNU Manual, like GNU software. Copies published by the Free
26 Software Foundation raise funds for GNU development.''
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 it as the
345 prefered part of @samp{multipart/alternative} messages, and you might
346 not notice there are other parts. See also
347 @code{gnus-buttonized-mime-types} (@pxref{MIME Commands, ,MIME Commands,
348 gnus, Gnus Manual}), to which adding @code{"multipart/alternative"}
349 enables you to choose manually one of two types those mails include.
350 For example, you can set those variables like:
353 (setq gnus-buttonized-mime-types
354 '("multipart/alternative" "multipart/signed")
355 mm-discouraged-alternatives
356 '("text/html" "image/.*"))
359 In this case, Gnus will display radio buttons for such a kind of spam
363 1. (*) multipart/alternative ( ) image/gif
365 2. (*) text/plain ( ) text/html
368 @item mm-inline-large-images
369 @vindex mm-inline-large-images
370 When displaying inline images that are larger than the window, Emacs
371 does not enable scrolling, which means that you cannot see the whole
372 image. To prevent this, the library tries to determine the image size
373 before displaying it inline, and if it doesn't fit the window, the
374 library will display it externally (e.g. with @samp{ImageMagick} or
375 @samp{xv}). Setting this variable to @code{t} disables this check and
376 makes the library display all inline images as inline, regardless of
379 @item mm-inline-override-types
380 @vindex mm-inline-override-types
381 @code{mm-inlined-types} may include regular expressions, for example to
382 specify that all @samp{text/.*} parts be displayed inline. If a user
383 prefers to have a type that matches such a regular expression be treated
384 as an attachment, that can be accomplished by setting this variable to a
385 list containing that type. For example assuming @code{mm-inlined-types}
386 includes @samp{text/.*}, then including @samp{text/html} in this
387 variable will cause @samp{text/html} parts to be treated as attachments.
389 @item mm-text-html-renderer
390 @vindex mm-text-html-renderer
391 This selects the function used to render @acronym{HTML}. The predefined
392 renderers are selected by the symbols @code{w3},
393 @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
394 information about emacs-w3m}, @code{links}, @code{lynx},
395 @code{w3m-standalone} or @code{html2text}. If @code{nil} use an
396 external viewer. You can also specify a function, which will be
397 called with a @acronym{MIME} handle as the argument.
399 @item mm-inline-text-html-with-images
400 @vindex mm-inline-text-html-with-images
401 Some @acronym{HTML} mails might have the trick of spammers using
402 @samp{<img>} tags. It is likely to be intended to verify whether you
403 have read the mail. You can prevent your personal informations from
404 leaking by setting this option to @code{nil} (which is the default).
405 It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
406 command @kbd{t} on the image anchor to show an image even if it is
407 @code{nil}.@footnote{The command @kbd{T} will load all images. If you
408 have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
411 @item mm-w3m-safe-url-regexp
412 @vindex mm-w3m-safe-url-regexp
413 A regular expression that matches safe URL names, i.e. URLs that are
414 unlikely to leak personal information when rendering @acronym{HTML}
415 email (the default value is @samp{\\`cid:}). If @code{nil} consider
418 @item mm-inline-text-html-with-w3m-keymap
419 @vindex mm-inline-text-html-with-w3m-keymap
420 You can use emacs-w3m command keys in the inlined text/html part by
421 setting this option to non-@code{nil}. The default value is @code{t}.
423 @item mm-external-terminal-program
424 @vindex mm-external-terminal-program
425 The program used to start an external terminal.
427 @item mm-enable-external
428 @vindex mm-enable-external
429 Indicate whether external @acronym{MIME} handlers should be used.
431 If @code{t}, all defined external @acronym{MIME} handlers are used. If
432 @code{nil}, files are saved to disk (@code{mailcap-save-binary-file}).
433 If it is the symbol @code{ask}, you are prompted before the external
434 @acronym{MIME} handler is invoked.
436 When you launch an attachment through mailcap (@pxref{mailcap}) an
437 attempt is made to use a safe viewer with the safest options---this isn't
438 the case if you save it to disk and launch it in a different way
439 (command line or double-clicking). Anyhow, if you want to be sure not
440 to launch any external programs, set this variable to @code{nil} or
445 @node Files and Directories
446 @section Files and Directories
450 @item mm-default-directory
451 @vindex mm-default-directory
452 The default directory for saving attachments. If @code{nil} use
453 @code{default-directory}.
455 @item mm-tmp-directory
456 @vindex mm-tmp-directory
457 Directory for storing temporary files.
459 @item mm-file-name-rewrite-functions
460 @vindex mm-file-name-rewrite-functions
461 A list of functions used for rewriting file names of @acronym{MIME}
462 parts. Each function is applied successively to the file name.
463 Ready-made functions include
466 @item mm-file-name-delete-control
467 @findex mm-file-name-delete-control
468 Delete all control characters.
470 @item mm-file-name-delete-gotchas
471 @findex mm-file-name-delete-gotchas
472 Delete characters that could have unintended consequences when used
473 with flawed shell scripts, i.e. @samp{|}, @samp{>} and @samp{<}; and
474 @samp{-}, @samp{.} as the first character.
476 @item mm-file-name-delete-whitespace
477 @findex mm-file-name-delete-whitespace
478 Remove all whitespace.
480 @item mm-file-name-trim-whitespace
481 @findex mm-file-name-trim-whitespace
482 Remove leading and trailing whitespace.
484 @item mm-file-name-collapse-whitespace
485 @findex mm-file-name-collapse-whitespace
486 Collapse multiple whitespace characters.
488 @item mm-file-name-replace-whitespace
489 @findex mm-file-name-replace-whitespace
490 @vindex mm-file-name-replace-whitespace
491 Replace whitespace with underscores. Set the variable
492 @code{mm-file-name-replace-whitespace} to any other string if you do
493 not like underscores.
496 The standard Emacs functions @code{capitalize}, @code{downcase},
497 @code{upcase} and @code{upcase-initials} might also prove useful.
499 @item mm-path-name-rewrite-functions
500 @vindex mm-path-name-rewrite-functions
501 List of functions used for rewriting the full file names of @acronym{MIME}
502 parts. This is used when viewing parts externally, and is meant for
503 transforming the absolute name so that non-compliant programs can find
504 the file where it's saved.
511 Here's an example viewer for displaying @code{text/enriched} inline:
514 (defun mm-display-enriched-inline (handle)
517 (mm-insert-part handle)
518 (save-window-excursion
519 (enriched-decode (point-min) (point-max))
520 (setq text (buffer-string))))
521 (mm-insert-inline handle text)))
524 We see that the function takes a @acronym{MIME} handle as its parameter. It
525 then goes to a temporary buffer, inserts the text of the part, does some
526 work on the text, stores the result, goes back to the buffer it was
527 called from and inserts the result.
529 The two important helper functions here are @code{mm-insert-part} and
530 @code{mm-insert-inline}. The first function inserts the text of the
531 handle in the current buffer. It handles charset and/or content
532 transfer decoding. The second function just inserts whatever text you
533 tell it to insert, but it also sets things up so that the text can be
534 ``undisplayed'' in a convenient manner.
540 @cindex MIME Composing
542 @cindex MIME Meta Language
544 Creating a @acronym{MIME} message is boring and non-trivial. Therefore,
545 a library called @code{mml} has been defined that parses a language
546 called @acronym{MML} (@acronym{MIME} Meta Language) and generates
547 @acronym{MIME} messages.
549 @findex mml-generate-mime
550 The main interface function is @code{mml-generate-mime}. It will
551 examine the contents of the current (narrowed-to) buffer and return a
552 string containing the @acronym{MIME} message.
555 * Simple MML Example:: An example @acronym{MML} document.
556 * MML Definition:: All valid @acronym{MML} elements.
557 * Advanced MML Example:: Another example @acronym{MML} document.
558 * Encoding Customization:: Variables that affect encoding.
559 * Charset Translation:: How charsets are mapped from @sc{mule} to @acronym{MIME}.
560 * Conversion:: Going from @acronym{MIME} to @acronym{MML} and vice versa.
561 * Flowed text:: Soft and hard newlines.
565 @node Simple MML Example
566 @section Simple MML Example
568 Here's a simple @samp{multipart/alternative}:
571 <#multipart type=alternative>
572 This is a plain text part.
573 <#part type=text/enriched>
574 <center>This is a centered enriched part</center>
578 After running this through @code{mml-generate-mime}, we get this:
581 Content-Type: multipart/alternative; boundary="=-=-="
587 This is a plain text part.
590 Content-Type: text/enriched
593 <center>This is a centered enriched part</center>
600 @section MML Definition
602 The @acronym{MML} language is very simple. It looks a bit like an SGML
603 application, but it's not.
605 The main concept of @acronym{MML} is the @dfn{part}. Each part can be of a
606 different type or use a different charset. The way to delineate a part
607 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
608 with the @samp{<#multipart ...>} tag. Parts are ended by the
609 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
610 @samp{<#part ...>} tags are also closed by the next open tag.
612 There's also the @samp{<#external ...>} tag. These introduce
613 @samp{external/message-body} parts.
615 Each tag can contain zero or more parameters on the form
616 @samp{parameter=value}. The values may be enclosed in quotation marks,
617 but that's not necessary unless the value contains white space. So
618 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
620 The following parameters have meaning in @acronym{MML}; parameters that have no
621 meaning are ignored. The @acronym{MML} parameter names are the same as the
622 @acronym{MIME} parameter names; the things in the parentheses say which
623 header it will be used in.
627 The @acronym{MIME} type of the part (@code{Content-Type}).
630 Use the contents of the file in the body of the part
631 (@code{Content-Disposition}).
634 The contents of the body of the part are to be encoded in the character
635 set specified (@code{Content-Type}). @xref{Charset Translation}.
638 Might be used to suggest a file name if the part is to be saved
639 to a file (@code{Content-Type}).
642 Valid values are @samp{inline} and @samp{attachment}
643 (@code{Content-Disposition}).
646 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
647 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
651 A description of the part (@code{Content-Description}).
654 RFC822 date when the part was created (@code{Content-Disposition}).
656 @item modification-date
657 RFC822 date when the part was modified (@code{Content-Disposition}).
660 RFC822 date when the part was read (@code{Content-Disposition}).
663 Who to encrypt/sign the part to. This field is used to override any
664 auto-detection based on the To/CC headers.
667 Identity used to sign the part. This field is used to override the
671 The size (in octets) of the part (@code{Content-Disposition}).
674 What technology to sign this @acronym{MML} part with (@code{smime}, @code{pgp}
678 What technology to encrypt this @acronym{MML} part with (@code{smime},
679 @code{pgp} or @code{pgpmime})
683 Parameters for @samp{text/plain}:
687 Formatting parameter for the text, valid values include @samp{fixed}
688 (the default) and @samp{flowed}. Normally you do not specify this
689 manually, since it requires the textual body to be formatted in a
690 special way described in RFC 2646. @xref{Flowed text}.
693 Parameters for @samp{application/octet-stream}:
697 Type of the part; informal---meant for human readers
698 (@code{Content-Type}).
701 Parameters for @samp{message/external-body}:
705 A word indicating the supported access mechanism by which the file may
706 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
707 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
710 The RFC822 date after which the file may no longer be fetched.
711 (@code{Content-Type}.)
714 The size (in octets) of the file. (@code{Content-Type}.)
717 Valid values are @samp{read} and @samp{read-write}
718 (@code{Content-Type}).
722 Parameters for @samp{sign=smime}:
727 File containing key and certificate for signer.
731 Parameters for @samp{encrypt=smime}:
736 File containing certificate for recipient.
741 @node Advanced MML Example
742 @section Advanced MML Example
744 Here's a complex multipart message. It's a @samp{multipart/mixed} that
745 contains many parts, one of which is a @samp{multipart/alternative}.
748 <#multipart type=mixed>
749 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
750 <#multipart type=alternative>
751 This is a plain text part.
752 <#part type=text/enriched name=enriched.txt>
753 <center>This is a centered enriched part</center>
755 This is a new plain text part.
756 <#part disposition=attachment>
757 This plain text part is an attachment.
761 And this is the resulting @acronym{MIME} message:
764 Content-Type: multipart/mixed; boundary="=-=-="
772 Content-Type: image/jpeg;
774 Content-Disposition: inline;
776 Content-Transfer-Encoding: base64
778 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
779 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
780 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
781 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
782 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
783 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
784 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
785 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
786 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
787 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
788 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
789 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
790 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
791 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
792 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
793 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
794 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
797 Content-Type: multipart/alternative; boundary="==-=-="
803 This is a plain text part.
806 Content-Type: text/enriched;
810 <center>This is a centered enriched part</center>
816 This is a new plain text part.
819 Content-Disposition: attachment
822 This plain text part is an attachment.
827 @node Encoding Customization
828 @section Encoding Customization
832 @item mm-body-charset-encoding-alist
833 @vindex mm-body-charset-encoding-alist
834 Mapping from @acronym{MIME} charset to encoding to use. This variable is
835 usually used except, e.g., when other requirements force a specific
836 encoding (digitally signed messages require 7bit encodings). The
840 ((iso-2022-jp . 7bit)
841 (iso-2022-jp-2 . 7bit)
847 As an example, if you do not want to have ISO-8859-1 characters
848 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
849 this variable. You can override this setting on a per-message basis
850 by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
852 @item mm-coding-system-priorities
853 @vindex mm-coding-system-priorities
854 Prioritize coding systems to use for outgoing messages. The default
855 is @code{nil}, which means to use the defaults in Emacs, but is
856 @code{(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)} when
857 running Emacs in the Japanese language environment. It is a list of
858 coding system symbols (aliases of coding systems are also allowed, use
859 @kbd{M-x describe-coding-system} to make sure you are specifying correct
860 coding system names). For example, if you have configured Emacs
861 to prefer UTF-8, but wish that outgoing messages should be sent in
862 ISO-8859-1 if possible, you can set this variable to
863 @code{(iso-8859-1)}. You can override this setting on a per-message
864 basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}).
866 @item mm-content-transfer-encoding-defaults
867 @vindex mm-content-transfer-encoding-defaults
868 Mapping from @acronym{MIME} types to encoding to use. This variable is usually
869 used except, e.g., when other requirements force a safer encoding
870 (digitally signed messages require 7bit encoding). Besides the normal
871 @acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
872 each case the most efficient of quoted-printable and base64 should be
875 @code{qp-or-base64} has another effect. It will fold long lines so that
876 MIME parts may not be broken by MTA. So do @code{quoted-printable} and
879 Note that it affects body encoding only when a part is a raw forwarded
880 message (which will be made by @code{gnus-summary-mail-forward} with the
881 arg 2 for example) or is neither the @samp{text/*} type nor the
882 @samp{message/*} type. Even though in those cases, you can override
883 this setting on a per-message basis by using the @code{encoding}
884 @acronym{MML} tag (@pxref{MML Definition}).
886 @item mm-use-ultra-safe-encoding
887 @vindex mm-use-ultra-safe-encoding
888 When this is non-@code{nil}, it means that textual parts are encoded as
889 quoted-printable if they contain lines longer than 76 characters or
890 starting with "From " in the body. Non-7bit encodings (8bit, binary)
891 are generally disallowed. This reduce the probability that a non-8bit
892 clean MTA or MDA changes the message. This should never be set
893 directly, but bound by other functions when necessary (e.g., when
894 encoding messages that are to be digitally signed).
898 @node Charset Translation
899 @section Charset Translation
902 During translation from @acronym{MML} to @acronym{MIME}, for each
903 @acronym{MIME} part which has been composed inside Emacs, an appropriate
904 charset has to be chosen.
906 @vindex mail-parse-charset
907 If you are running a non-@sc{mule} Emacs, this process is simple: If the
908 part contains any non-@acronym{ASCII} (8-bit) characters, the @acronym{MIME} charset
909 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
910 variable directly, though. If you want to change the default charset,
911 please consult the documentation of the package which you use to process
912 @acronym{MIME} messages.
913 @xref{Various Message Variables, , Various Message Variables, message,
914 Message Manual}, for example.)
915 If there are only @acronym{ASCII} characters, the @acronym{MIME} charset US-ASCII is
921 @vindex mm-mime-mule-charset-alist
922 Things are slightly more complicated when running Emacs with @sc{mule}
923 support. In this case, a list of the @sc{mule} charsets used in the
924 part is obtained, and the @sc{mule} charsets are translated to
925 @acronym{MIME} charsets by consulting the table provided by Emacs itself
926 or the variable @code{mm-mime-mule-charset-alist} for XEmacs.
927 If this results in a single @acronym{MIME} charset, this is used to encode
928 the part. But if the resulting list of @acronym{MIME} charsets contains more
929 than one element, two things can happen: If it is possible to encode the
930 part via UTF-8, this charset is used. (For this, Emacs must support
931 the @code{utf-8} coding system, and the part must consist entirely of
932 characters which have Unicode counterparts.) If UTF-8 is not available
933 for some reason, the part is split into several ones, so that each one
934 can be encoded with a single @acronym{MIME} charset. The part can only be
935 split at line boundaries, though---if more than one @acronym{MIME} charset is
936 required to encode a single line, it is not possible to encode the part.
938 When running Emacs with @sc{mule} support, the preferences for which
939 coding system to use is inherited from Emacs itself. This means that
940 if Emacs is set up to prefer UTF-8, it will be used when encoding
941 messages. You can modify this by altering the
942 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
945 The charset to be used can be overridden by setting the @code{charset}
946 @acronym{MML} tag (@pxref{MML Definition}) when composing the message.
948 The encoding of characters (quoted-printable, 8bit etc) is orthogonal
949 to the discussion here, and is controlled by the variables
950 @code{mm-body-charset-encoding-alist} and
951 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
958 A (multipart) @acronym{MIME} message can be converted to @acronym{MML}
959 with the @code{mime-to-mml} function. It works on the message in the
960 current buffer, and substitutes @acronym{MML} markup for @acronym{MIME}
961 boundaries. Non-textual parts do not have their contents in the buffer,
962 but instead have the contents in separate buffers that are referred to
963 from the @acronym{MML} tags.
966 An @acronym{MML} message can be converted back to @acronym{MIME} by the
967 @code{mml-to-mime} function.
969 These functions are in certain senses ``lossy''---you will not get back
970 an identical message if you run @code{mime-to-mml} and then
971 @code{mml-to-mime}. Not only will trivial things like the order of the
972 headers differ, but the contents of the headers may also be different.
973 For instance, the original message may use base64 encoding on text,
974 while @code{mml-to-mime} may decide to use quoted-printable encoding, and
977 In essence, however, these two functions should be the inverse of each
978 other. The resulting contents of the message should remain equivalent,
984 @cindex format=flowed
986 The Emacs @acronym{MIME} library will respect the @code{use-hard-newlines}
987 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
988 emacs, Emacs Manual}) when encoding a message, and the
989 ``format=flowed'' Content-Type parameter when decoding a message.
991 On encoding text, regardless of @code{use-hard-newlines}, lines
992 terminated by soft newline characters are filled together and wrapped
993 after the column decided by @code{fill-flowed-encode-column}.
994 Quotation marks (matching @samp{^>* ?}) are respected. The variable
995 controls how the text will look in a client that does not support
996 flowed text, the default is to wrap after 66 characters. If hard
997 newline characters are not present in the buffer, no flow encoding
1000 On decoding flowed text, lines with soft newline characters are filled
1001 together and wrapped after the column decided by
1002 @code{fill-flowed-display-column}. The default is to wrap after
1006 @item mm-fill-flowed
1007 @vindex mm-fill-flowed
1008 If non-@code{nil} a format=flowed article will be displayed flowed.
1012 @node Interface Functions
1013 @chapter Interface Functions
1014 @cindex interface functions
1017 The @code{mail-parse} library is an abstraction over the actual
1018 low-level libraries that are described in the next chapter.
1020 Standards change, and so programs have to change to fit in the new
1021 mold. For instance, RFC2045 describes a syntax for the
1022 @code{Content-Type} header that only allows @acronym{ASCII} characters in the
1023 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
1024 for continuation headers and non-@acronym{ASCII} characters.
1026 The traditional way to deal with this is just to update the library
1027 functions to parse the new syntax. However, this is sometimes the wrong
1028 thing to do. In some instances it may be vital to be able to understand
1029 both the old syntax as well as the new syntax, and if there is only one
1030 library, one must choose between the old version of the library and the
1031 new version of the library.
1033 The Emacs @acronym{MIME} library takes a different tack. It defines a
1034 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
1035 and so on) that parses strictly according to the corresponding
1036 standard. However, normal programs would not use the functions
1037 provided by these libraries directly, but instead use the functions
1038 provided by the @code{mail-parse} library. The functions in this
1039 library are just aliases to the corresponding functions in the latest
1040 low-level libraries. Using this scheme, programs get a consistent
1041 interface they can use, and library developers are free to create
1042 write code that handles new standards.
1044 The following functions are defined by this library:
1047 @item mail-header-parse-content-type
1048 @findex mail-header-parse-content-type
1049 Parse a @code{Content-Type} header and return a list on the following
1054 (attribute1 . value1)
1055 (attribute2 . value2)
1062 (mail-header-parse-content-type
1063 "image/gif; name=\"b980912.gif\"")
1064 @result{} ("image/gif" (name . "b980912.gif"))
1067 @item mail-header-parse-content-disposition
1068 @findex mail-header-parse-content-disposition
1069 Parse a @code{Content-Disposition} header and return a list on the same
1070 format as the function above.
1072 @item mail-content-type-get
1073 @findex mail-content-type-get
1074 Takes two parameters---a list on the format above, and an attribute.
1075 Returns the value of the attribute.
1078 (mail-content-type-get
1079 '("image/gif" (name . "b980912.gif")) 'name)
1080 @result{} "b980912.gif"
1083 @item mail-header-encode-parameter
1084 @findex mail-header-encode-parameter
1085 Takes a parameter string and returns an encoded version of the string.
1086 This is used for parameters in headers like @code{Content-Type} and
1087 @code{Content-Disposition}.
1089 @item mail-header-remove-comments
1090 @findex mail-header-remove-comments
1091 Return a comment-free version of a header.
1094 (mail-header-remove-comments
1095 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1096 @result{} "Gnus/5.070027 "
1099 @item mail-header-remove-whitespace
1100 @findex mail-header-remove-whitespace
1101 Remove linear white space from a header. Space inside quoted strings
1102 and comments is preserved.
1105 (mail-header-remove-whitespace
1106 "image/gif; name=\"Name with spaces\"")
1107 @result{} "image/gif;name=\"Name with spaces\""
1110 @item mail-header-get-comment
1111 @findex mail-header-get-comment
1112 Return the last comment in a header.
1115 (mail-header-get-comment
1116 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1117 @result{} "Finnish Landrace"
1120 @item mail-header-parse-address
1121 @findex mail-header-parse-address
1122 Parse an address and return a list containing the mailbox and the
1126 (mail-header-parse-address
1127 "Hrvoje Niksic <hniksic@@srce.hr>")
1128 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1131 @item mail-header-parse-addresses
1132 @findex mail-header-parse-addresses
1133 Parse a string with list of addresses and return a list of elements like
1134 the one described above.
1137 (mail-header-parse-addresses
1138 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1139 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1140 ("sb@@metis.no" . "Steinar Bang"))
1143 @item mail-header-parse-date
1144 @findex mail-header-parse-date
1145 Parse a date string and return an Emacs time structure.
1147 @item mail-narrow-to-head
1148 @findex mail-narrow-to-head
1149 Narrow the buffer to the header section of the buffer. Point is placed
1150 at the beginning of the narrowed buffer.
1152 @item mail-header-narrow-to-field
1153 @findex mail-header-narrow-to-field
1154 Narrow the buffer to the header under point. Understands continuation
1157 @item mail-header-fold-field
1158 @findex mail-header-fold-field
1159 Fold the header under point.
1161 @item mail-header-unfold-field
1162 @findex mail-header-unfold-field
1163 Unfold the header under point.
1165 @item mail-header-field-value
1166 @findex mail-header-field-value
1167 Return the value of the field under point.
1169 @item mail-encode-encoded-word-region
1170 @findex mail-encode-encoded-word-region
1171 Encode the non-@acronym{ASCII} words in the region. For instance,
1172 @samp{Na@"{@dotless{i}}ve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1174 @item mail-encode-encoded-word-buffer
1175 @findex mail-encode-encoded-word-buffer
1176 Encode the non-@acronym{ASCII} words in the current buffer. This function is
1177 meant to be called narrowed to the headers of a message.
1179 @item mail-encode-encoded-word-string
1180 @findex mail-encode-encoded-word-string
1181 Encode the words that need encoding in a string, and return the result.
1184 (mail-encode-encoded-word-string
1185 "This is na@"{@dotless{i}}ve, baby")
1186 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1189 @item mail-decode-encoded-word-region
1190 @findex mail-decode-encoded-word-region
1191 Decode the encoded words in the region.
1193 @item mail-decode-encoded-word-string
1194 @findex mail-decode-encoded-word-string
1195 Decode the encoded words in the string and return the result.
1198 (mail-decode-encoded-word-string
1199 "This is =?iso-8859-1?q?na=EFve,?= baby")
1200 @result{} "This is na@"{@dotless{i}}ve, baby"
1205 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1206 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1207 in the subsequent sections.
1211 @node Basic Functions
1212 @chapter Basic Functions
1214 This chapter describes the basic, ground-level functions for parsing and
1215 handling. Covered here is parsing @code{From} lines, removing comments
1216 from header lines, decoding encoded words, parsing date headers and so
1217 on. High-level functionality is dealt with in the first chapter
1218 (@pxref{Decoding and Viewing}).
1221 * rfc2045:: Encoding @code{Content-Type} headers.
1222 * rfc2231:: Parsing @code{Content-Type} headers.
1223 * ietf-drums:: Handling mail headers defined by RFC822bis.
1224 * rfc2047:: En/decoding encoded words in headers.
1225 * time-date:: Functions for parsing dates and manipulating time.
1226 * qp:: Quoted-Printable en/decoding.
1227 * base64:: Base64 en/decoding.
1228 * binhex:: Binhex decoding.
1229 * uudecode:: Uuencode decoding.
1230 * yenc:: Yenc decoding.
1231 * rfc1843:: Decoding HZ-encoded text.
1232 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1239 RFC2045 is the ``main'' @acronym{MIME} document, and as such, one would
1240 imagine that there would be a lot to implement. But there isn't, since
1241 most of the implementation details are delegated to the subsequent
1244 So @file{rfc2045.el} has only a single function:
1247 @item rfc2045-encode-string
1248 @findex rfc2045-encode-string
1249 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1250 @var{value} will be quoted if there are non-safe characters in it.
1257 RFC2231 defines a syntax for the @code{Content-Type} and
1258 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1259 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1262 In short, these headers look something like this:
1265 Content-Type: application/x-stuff;
1266 title*0*=us-ascii'en'This%20is%20even%20more%20;
1267 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1271 They usually aren't this bad, though.
1273 The following functions are defined by this library:
1276 @item rfc2231-parse-string
1277 @findex rfc2231-parse-string
1278 Parse a @code{Content-Type} header and return a list describing its
1282 (rfc2231-parse-string
1283 "application/x-stuff;
1284 title*0*=us-ascii'en'This%20is%20even%20more%20;
1285 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1286 title*2=\"isn't it!\"")
1287 @result{} ("application/x-stuff"
1288 (title . "This is even more ***fun*** isn't it!"))
1291 @item rfc2231-get-value
1292 @findex rfc2231-get-value
1293 Takes one of the lists on the format above and returns
1294 the value of the specified attribute.
1296 @item rfc2231-encode-string
1297 @findex rfc2231-encode-string
1298 Encode a parameter in headers likes @code{Content-Type} and
1299 @code{Content-Disposition}.
1307 @dfn{drums} is an IETF working group that is working on the replacement
1310 The functions provided by this library include:
1313 @item ietf-drums-remove-comments
1314 @findex ietf-drums-remove-comments
1315 Remove the comments from the argument and return the results.
1317 @item ietf-drums-remove-whitespace
1318 @findex ietf-drums-remove-whitespace
1319 Remove linear white space from the string and return the results.
1320 Spaces inside quoted strings and comments are left untouched.
1322 @item ietf-drums-get-comment
1323 @findex ietf-drums-get-comment
1324 Return the last most comment from the string.
1326 @item ietf-drums-parse-address
1327 @findex ietf-drums-parse-address
1328 Parse an address string and return a list that contains the mailbox and
1329 the plain text name.
1331 @item ietf-drums-parse-addresses
1332 @findex ietf-drums-parse-addresses
1333 Parse a string that contains any number of comma-separated addresses and
1334 return a list that contains mailbox/plain text pairs.
1336 @item ietf-drums-parse-date
1337 @findex ietf-drums-parse-date
1338 Parse a date string and return an Emacs time structure.
1340 @item ietf-drums-narrow-to-header
1341 @findex ietf-drums-narrow-to-header
1342 Narrow the buffer to the header section of the current buffer.
1350 RFC2047 (Message Header Extensions for Non-@acronym{ASCII} Text) specifies how
1351 non-@acronym{ASCII} text in headers are to be encoded. This is actually rather
1352 complicated, so a number of variables are necessary to tweak what this
1355 The following variables are tweakable:
1358 @item rfc2047-header-encoding-alist
1359 @vindex rfc2047-header-encoding-alist
1360 This is an alist of header / encoding-type pairs. Its main purpose is
1361 to prevent encoding of certain headers.
1363 The keys can either be header regexps, or @code{t}.
1365 The values can be @code{nil}, in which case the header(s) in question
1366 won't be encoded, @code{mime}, which means that they will be encoded, or
1367 @code{address-mime}, which means the header(s) will be encoded carefully
1368 assuming they contain addresses.
1370 @item rfc2047-charset-encoding-alist
1371 @vindex rfc2047-charset-encoding-alist
1372 RFC2047 specifies two forms of encoding---@code{Q} (a
1373 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1374 specifies which charset should use which encoding.
1376 @item rfc2047-encode-function-alist
1377 @vindex rfc2047-encode-function-alist
1378 This is an alist of encoding / function pairs. The encodings are
1379 @code{Q}, @code{B} and @code{nil}.
1381 @item rfc2047-encoded-word-regexp
1382 @vindex rfc2047-encoded-word-regexp
1383 When decoding words, this library looks for matches to this regexp.
1385 @item rfc2047-encode-encoded-words
1386 @vindex rfc2047-encode-encoded-words
1387 The boolean variable specifies whether encoded words
1388 (e.g. @samp{=?hello?=}) should be encoded again.
1392 Those were the variables, and these are this functions:
1395 @item rfc2047-narrow-to-field
1396 @findex rfc2047-narrow-to-field
1397 Narrow the buffer to the header on the current line.
1399 @item rfc2047-encode-message-header
1400 @findex rfc2047-encode-message-header
1401 Should be called narrowed to the header of a message. Encodes according
1402 to @code{rfc2047-header-encoding-alist}.
1404 @item rfc2047-encode-region
1405 @findex rfc2047-encode-region
1406 Encodes all encodable words in the region specified.
1408 @item rfc2047-encode-string
1409 @findex rfc2047-encode-string
1410 Encode a string and return the results.
1412 @item rfc2047-decode-region
1413 @findex rfc2047-decode-region
1414 Decode the encoded words in the region.
1416 @item rfc2047-decode-string
1417 @findex rfc2047-decode-string
1418 Decode a string and return the results.
1420 @item rfc2047-encode-parameter
1421 @findex rfc2047-encode-parameter
1422 Encode a parameter in the RFC2047-like style. This is a replacement for
1423 the @code{rfc2231-encode-string} function. @xref{rfc2231}.
1425 When attaching files as @acronym{MIME} parts, we should use the RFC2231
1426 encoding to specify the file names containing non-@acronym{ASCII}
1427 characters. However, many mail softwares don't support it in practice
1428 and recipients won't be able to extract files with correct names.
1429 Instead, the RFC2047-like encoding is acceptable generally. This
1430 function provides the very RFC2047-like encoding, resigning to such a
1431 regrettable trend. To use it, put the following line in your
1432 @file{~/.gnus.el} file:
1435 (defalias 'mail-header-encode-parameter 'rfc2047-encode-parameter)
1444 While not really a part of the @acronym{MIME} library, it is convenient to
1445 document this library here. It deals with parsing @code{Date} headers
1446 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1449 These functions convert between five formats: A date string, an Emacs
1450 time structure, a decoded time list, a second number, and a day number.
1452 Here's a bunch of time/date/second/day examples:
1455 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1456 @result{} (54 21 12 12 9 1998 6 nil 7200)
1458 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1459 @result{} (13818 19266)
1461 (time-to-seconds '(13818 19266))
1462 @result{} 905595714.0
1464 (seconds-to-time 905595714.0)
1465 @result{} (13818 19266 0)
1467 (time-to-days '(13818 19266))
1470 (days-to-time 729644)
1471 @result{} (961933 65536)
1473 (time-since '(13818 19266))
1476 (time-less-p '(13818 19266) '(13818 19145))
1479 (subtract-time '(13818 19266) '(13818 19145))
1482 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1483 "Sat Sep 07 12:21:54 1998 +0200")
1486 (date-leap-year-p 2000)
1489 (time-to-day-in-year '(13818 19266))
1492 (time-to-number-of-days
1494 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1495 @result{} 4.146122685185185
1498 And finally, we have @code{safe-date-to-time}, which does the same as
1499 @code{date-to-time}, but returns a zero time if the date is
1500 syntactically malformed.
1502 The five data representations used are the following:
1506 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1507 12:21:54 1998 +0200"}.
1510 An internal Emacs time. For instance: @code{(13818 26466)}.
1513 A floating point representation of the internal Emacs time. For
1514 instance: @code{905595714.0}.
1517 An integer number representing the number of days since 00000101. For
1518 instance: @code{729644}.
1521 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1525 All the examples above represent the same moment.
1527 These are the functions available:
1531 Take a date and return a time.
1533 @item time-to-seconds
1534 Take a time and return seconds.
1536 @item seconds-to-time
1537 Take seconds and return a time.
1540 Take a time and return days.
1543 Take days and return a time.
1546 Take a date and return days.
1548 @item time-to-number-of-days
1549 Take a time and return the number of days that represents.
1551 @item safe-date-to-time
1552 Take a date and return a time. If the date is not syntactically valid,
1553 return a ``zero'' time.
1556 Take two times and say whether the first time is less (i. e., earlier)
1557 than the second time.
1560 Take a time and return a time saying how long it was since that time.
1563 Take two times and subtract the second from the first. I. e., return
1564 the time between the two times.
1567 Take two days and return the number of days between those two days.
1569 @item date-leap-year-p
1570 Take a year number and say whether it's a leap year.
1572 @item time-to-day-in-year
1573 Take a time and return the day number within the year that the time is
1582 This library deals with decoding and encoding Quoted-Printable text.
1584 Very briefly explained, qp encoding means translating all 8-bit
1585 characters (and lots of control characters) into things that look like
1586 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1589 The following functions are defined by the library:
1592 @item quoted-printable-decode-region
1593 @findex quoted-printable-decode-region
1594 QP-decode all the encoded text in the specified region.
1596 @item quoted-printable-decode-string
1597 @findex quoted-printable-decode-string
1598 Decode the QP-encoded text in a string and return the results.
1600 @item quoted-printable-encode-region
1601 @findex quoted-printable-encode-region
1602 QP-encode all the encodable characters in the specified region. The third
1603 optional parameter @var{fold} specifies whether to fold long lines.
1604 (Long here means 72.)
1606 @item quoted-printable-encode-string
1607 @findex quoted-printable-encode-string
1608 QP-encode all the encodable characters in a string and return the
1618 Base64 is an encoding that encodes three bytes into four characters,
1619 thereby increasing the size by about 33%. The alphabet used for
1620 encoding is very resistant to mangling during transit.
1622 The following functions are defined by this library:
1625 @item base64-encode-region
1626 @findex base64-encode-region
1627 base64 encode the selected region. Return the length of the encoded
1628 text. Optional third argument @var{no-line-break} means do not break
1629 long lines into shorter lines.
1631 @item base64-encode-string
1632 @findex base64-encode-string
1633 base64 encode a string and return the result.
1635 @item base64-decode-region
1636 @findex base64-decode-region
1637 base64 decode the selected region. Return the length of the decoded
1638 text. If the region can't be decoded, return @code{nil} and don't
1641 @item base64-decode-string
1642 @findex base64-decode-string
1643 base64 decode a string and return the result. If the string can't be
1644 decoded, @code{nil} is returned.
1655 @code{binhex} is an encoding that originated in Macintosh environments.
1656 The following function is supplied to deal with these:
1659 @item binhex-decode-region
1660 @findex binhex-decode-region
1661 Decode the encoded text in the region. If given a third parameter, only
1662 decode the @code{binhex} header and return the filename.
1671 @code{uuencode} is probably still the most popular encoding of binaries
1672 used on Usenet, although @code{base64} rules the mail world.
1674 The following function is supplied by this package:
1677 @item uudecode-decode-region
1678 @findex uudecode-decode-region
1679 Decode the text in the region.
1687 @code{yenc} is used for encoding binaries on Usenet. The following
1688 function is supplied by this package:
1691 @item yenc-decode-region
1692 @findex yenc-decode-region
1693 Decode the encoded text in the region.
1704 RFC1843 deals with mixing Chinese and @acronym{ASCII} characters in messages. In
1705 essence, RFC1843 switches between @acronym{ASCII} and Chinese by doing this:
1708 This sentence is in @acronym{ASCII}.
1709 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1712 Simple enough, and widely used in China.
1714 The following functions are available to handle this encoding:
1717 @item rfc1843-decode-region
1718 Decode HZ-encoded text in the region.
1720 @item rfc1843-decode-string
1721 Decode a HZ-encoded string and return the result.
1729 The @file{~/.mailcap} file is parsed by most @acronym{MIME}-aware message
1730 handlers and describes how elements are supposed to be displayed.
1731 Here's an example file:
1735 audio/wav; wavplayer %s
1736 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1739 This says that all image files should be displayed with @code{gimp},
1740 that WAVE audio files should be played by @code{wavplayer}, and that
1741 MS-WORD files should be inlined by @code{catdoc}.
1743 The @code{mailcap} library parses this file, and provides functions for
1747 @item mailcap-mime-data
1748 @vindex mailcap-mime-data
1749 This variable is an alist of alists containing backup viewing rules.
1753 Interface functions:
1756 @item mailcap-parse-mailcaps
1757 @findex mailcap-parse-mailcaps
1758 Parse the @file{~/.mailcap} file.
1760 @item mailcap-mime-info
1761 Takes a @acronym{MIME} type as its argument and returns the matching viewer.
1771 The Emacs @acronym{MIME} library implements handling of various elements
1772 according to a (somewhat) large number of RFCs, drafts and standards
1773 documents. This chapter lists the relevant ones. They can all be
1774 fetched from @uref{http://quimby.gnus.org/notes/}.
1779 Standard for the Format of ARPA Internet Text Messages.
1782 Standard for Interchange of USENET Messages
1785 Format of Internet Message Bodies
1791 Message Header Extensions for Non-@acronym{ASCII} Text
1794 Registration Procedures
1797 Conformance Criteria and Examples
1800 @acronym{MIME} Parameter Value and Encoded Word Extensions: Character Sets,
1801 Languages, and Continuations
1804 HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1805 @acronym{ASCII} characters
1807 @item draft-ietf-drums-msg-fmt-05.txt
1808 Draft for the successor of RFC822
1811 The @acronym{MIME} Multipart/Related Content-type
1814 The Multipart/Report Content Type for the Reporting of Mail System
1815 Administrative Messages
1818 Communicating Presentation Information in Internet Messages: The
1819 Content-Disposition Header Field
1822 Documentation of the text/plain format parameter for flowed text.
1838 @c coding: iso-8859-1