This manual documents the libraries used to compose and display
@sc{mime} messages.
-This is not a manual meant for users; it's a manual directed at people
-who want to write functions and commands that manipulate @sc{mime}
-elements.
+This manual is directed at users who want to modify the behaviour of
+the MIME encoding/decoding process or want a more detailed picture of
+how the Emacs MIME library works, and people who want to write
+functions and commands that manipulate @sc{mime} elements.
@sc{mime} is short for @dfn{Multipurpose Internet Mail Extensions}.
This standard is documented in a number of RFCs; mainly RFC2045 (Format
read at least RFC2045 and RFC2047.
@menu
-* Interface Functions:: An abstraction over the basic functions.
-* Basic Functions:: Utility and basic parsing functions.
* Decoding and Viewing:: A framework for decoding and viewing.
* Composing:: MML; a language for describing @sc{mime} parts.
+* Interface Functions:: An abstraction over the basic functions.
+* Basic Functions:: Utility and basic parsing functions.
* Standards:: A summary of RFCs and working documents used.
* Index:: Function and variable index.
@end menu
-@node Interface Functions
-@chapter Interface Functions
-@cindex interface functions
-@cindex mail-parse
+@node Decoding and Viewing
+@chapter Decoding and Viewing
-The @code{mail-parse} library is an abstraction over the actual
-low-level libraries that are described in the next chapter.
+This chapter deals with decoding and viewing @sc{mime} messages on a
+higher level.
-Standards change, and so programs have to change to fit in the new
-mold. For instance, RFC2045 describes a syntax for the
-@code{Content-Type} header that only allows ASCII characters in the
-parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
-for continuation headers and non-ASCII characters.
+The main idea is to first analyze a @sc{mime} article, and then allow
+other programs to do things based on the list of @dfn{handles} that are
+returned as a result of this analysis.
-The traditional way to deal with this is just to update the library
-functions to parse the new syntax. However, this is sometimes the wrong
-thing to do. In some instances it may be vital to be able to understand
-both the old syntax as well as the new syntax, and if there is only one
-library, one must choose between the old version of the library and the
-new version of the library.
+@menu
+* Dissection:: Analyzing a @sc{mime} message.
+* Non-MIME:: Analyzing a non-@sc{mime} message.
+* Handles:: Handle manipulations.
+* Display:: Displaying handles.
+* Display Customization:: Variables that affect display.
+* New Viewers:: How to write your own viewers.
+@end menu
-The Emacs @sc{mime} library takes a different tack. It defines a
-series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
-and so on) that parses strictly according to the corresponding
-standard. However, normal programs would not use the functions
-provided by these libraries directly, but instead use the functions
-provided by the @code{mail-parse} library. The functions in this
-library are just aliases to the corresponding functions in the latest
-low-level libraries. Using this scheme, programs get a consistent
-interface they can use, and library developers are free to create
-write code that handles new standards.
-The following functions are defined by this library:
+@node Dissection
+@section Dissection
-@table @code
-@item mail-header-parse-content-type
-@findex mail-header-parse-content-type
-Parse a @code{Content-Type} header and return a list on the following
-format:
+The @code{mm-dissect-buffer} is the function responsible for dissecting
+a @sc{mime} article. If given a multipart message, it will recursively
+descend the message, following the structure, and return a tree of
+@sc{mime} handles that describes the structure of the message.
+
+@node Non-MIME
+@section Non-MIME
+
+Gnus also understands some non-@sc{mime} attachments, such as
+postscript, uuencode, binhex, shar, forward, gnatsweb, pgp. Each of
+these features can be disabled by add an item into
+@code{mm-uu-configure-list}. For example,
@lisp
-("type/subtype"
- (attribute1 . value1)
- (attribute2 . value2)
- ...)
+(require 'mm-uu)
+(add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
@end lisp
-Here's an example:
+@table @code
+@item postscript
+@findex postscript
+Postscript file.
-@example
-(mail-header-parse-content-type
- "image/gif; name=\"b980912.gif\"")
-@result{} ("image/gif" (name . "b980912.gif"))
-@end example
+@item uu
+@findex uu
+Uuencoded file.
-@item mail-header-parse-content-disposition
-@findex mail-header-parse-content-disposition
-Parse a @code{Content-Disposition} header and return a list on the same
-format as the function above.
+@item binhex
+@findex binhex
+Binhex encoded file.
-@item mail-content-type-get
-@findex mail-content-type-get
-Takes two parameters---a list on the format above, and an attribute.
-Returns the value of the attribute.
+@item shar
+@findex shar
+Shar archive file.
-@example
-(mail-content-type-get
- '("image/gif" (name . "b980912.gif")) 'name)
-@result{} "b980912.gif"
-@end example
+@item forward
+@findex forward
+Non-@sc{mime} forwarded message.
-@item mail-header-encode-parameter
-@findex mail-header-encode-parameter
-Takes a parameter string and returns an encoded version of the string.
-This is used for parameters in headers like @code{Content-Type} and
-@code{Content-Disposition}.
+@item gnatsweb
+@findex gnatsweb
+Gnatsweb attachment.
-@item mail-header-remove-comments
-@findex mail-header-remove-comments
-Return a comment-free version of a header.
+@item pgp-signed
+@findex pgp-signed
+PGP signed clear text.
-@example
-(mail-header-remove-comments
- "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
-@result{} "Gnus/5.070027 "
-@end example
+@item pgp-encrypted
+@findex pgp-encrypted
+PGP encrypted clear text.
-@item mail-header-remove-whitespace
-@findex mail-header-remove-whitespace
-Remove linear white space from a header. Space inside quoted strings
-and comments is preserved.
+@item pgp-key
+@findex pgp-key
+PGP public keys.
-@example
-(mail-header-remove-whitespace
- "image/gif; name=\"Name with spaces\"")
-@result{} "image/gif;name=\"Name with spaces\""
-@end example
+@item emacs-sources
+@findex emacs-sources
+Emacs source code. This item works only in the groups matching
+@code{mm-uu-emacs-sources-regexp}.
-@item mail-header-get-comment
-@findex mail-header-get-comment
-Return the last comment in a header.
+@end table
-@example
-(mail-header-get-comment
- "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
-@result{} "Finnish Landrace"
-@end example
+@node Handles
+@section Handles
-@item mail-header-parse-address
-@findex mail-header-parse-address
-Parse an address and return a list containing the mailbox and the
-plaintext name.
+A @sc{mime} handle is a list that fully describes a @sc{mime}
+component.
-@example
-(mail-header-parse-address
- "Hrvoje Niksic <hniksic@@srce.hr>")
-@result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
-@end example
+The following macros can be used to access elements in a handle:
-@item mail-header-parse-addresses
-@findex mail-header-parse-addresses
-Parse a string with list of addresses and return a list of elements like
-the one described above.
+@table @code
+@item mm-handle-buffer
+@findex mm-handle-buffer
+Return the buffer that holds the contents of the undecoded @sc{mime}
+part.
-@example
-(mail-header-parse-addresses
- "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
-@result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
- ("sb@@metis.no" . "Steinar Bang"))
-@end example
+@item mm-handle-type
+@findex mm-handle-type
+Return the parsed @code{Content-Type} of the part.
-@item mail-header-parse-date
-@findex mail-header-parse-date
-Parse a date string and return an Emacs time structure.
+@item mm-handle-encoding
+@findex mm-handle-encoding
+Return the @code{Content-Transfer-Encoding} of the part.
-@item mail-narrow-to-head
-@findex mail-narrow-to-head
-Narrow the buffer to the header section of the buffer. Point is placed
-at the beginning of the narrowed buffer.
+@item mm-handle-undisplayer
+@findex mm-handle-undisplayer
+Return the object that can be used to remove the displayed part (if it
+has been displayed).
-@item mail-header-narrow-to-field
-@findex mail-header-narrow-to-field
-Narrow the buffer to the header under point. Understands continuation
-headers.
+@item mm-handle-set-undisplayer
+@findex mm-handle-set-undisplayer
+Set the undisplayer object.
-@item mail-header-fold-field
-@findex mail-header-fold-field
-Fold the header under point.
+@item mm-handle-disposition
+@findex mm-handle-disposition
+Return the parsed @code{Content-Disposition} of the part.
-@item mail-header-unfold-field
-@findex mail-header-unfold-field
-Unfold the header under point.
+@item mm-handle-disposition
+@findex mm-handle-disposition
+Return the description of the part.
-@item mail-header-field-value
-@findex mail-header-field-value
-Return the value of the field under point.
+@item mm-get-content-id
+Returns the handle(s) referred to by @code{Content-ID}.
-@item mail-encode-encoded-word-region
-@findex mail-encode-encoded-word-region
-Encode the non-ASCII words in the region. For instance,
-@samp{Naïve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
+@end table
-@item mail-encode-encoded-word-buffer
-@findex mail-encode-encoded-word-buffer
-Encode the non-ASCII words in the current buffer. This function is
-meant to be called narrowed to the headers of a message.
-@item mail-encode-encoded-word-string
-@findex mail-encode-encoded-word-string
-Encode the words that need encoding in a string, and return the result.
+@node Display
+@section Display
-@example
-(mail-encode-encoded-word-string
- "This is naïve, baby")
-@result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
-@end example
+Functions for displaying, removing and saving.
-@item mail-decode-encoded-word-region
-@findex mail-decode-encoded-word-region
-Decode the encoded words in the region.
+@table @code
+@item mm-display-part
+@findex mm-display-part
+Display the part.
-@item mail-decode-encoded-word-string
-@findex mail-decode-encoded-word-string
-Decode the encoded words in the string and return the result.
+@item mm-remove-part
+@findex mm-remove-part
+Remove the part (if it has been displayed).
-@example
-(mail-decode-encoded-word-string
- "This is =?iso-8859-1?q?na=EFve,?= baby")
-@result{} "This is naïve, baby"
-@end example
+@item mm-inlinable-p
+@findex mm-inlinable-p
+Say whether a @sc{mime} type can be displayed inline.
-@end table
+@item mm-automatic-display-p
+@findex mm-automatic-display-p
+Say whether a @sc{mime} type should be displayed automatically.
-Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
-@code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
-in the subsequent sections.
+@item mm-destroy-part
+@findex mm-destroy-part
+Free all resources occupied by a part.
+@item mm-save-part
+@findex mm-save-part
+Offer to save the part in a file.
+@item mm-pipe-part
+@findex mm-pipe-part
+Offer to pipe the part to some process.
-@node Basic Functions
-@chapter Basic Functions
+@item mm-interactively-view-part
+@findex mm-interactively-view-part
+Prompt for a mailcap method to use to view the part.
-This chapter describes the basic, ground-level functions for parsing and
-handling. Covered here is parsing @code{From} lines, removing comments
-from header lines, decoding encoded words, parsing date headers and so
-on. High-level functionality is dealt with in the next chapter
-(@pxref{Decoding and Viewing}).
+@end table
-@menu
-* rfc2045:: Encoding @code{Content-Type} headers.
-* rfc2231:: Parsing @code{Content-Type} headers.
-* ietf-drums:: Handling mail headers defined by RFC822bis.
-* rfc2047:: En/decoding encoded words in headers.
-* time-date:: Functions for parsing dates and manipulating time.
-* qp:: Quoted-Printable en/decoding.
-* base64:: Base64 en/decoding.
-* binhex:: Binhex decoding.
-* uudecode:: Uuencode decoding.
-* rfc1843:: Decoding HZ-encoded text.
-* mailcap:: How parts are displayed is specified by the @file{.mailcap} file
-@end menu
+@node Display Customization
+@section Display Customization
-@node rfc2045
-@section rfc2045
+@table @code
-RFC2045 is the ``main'' @sc{mime} document, and as such, one would
-imagine that there would be a lot to implement. But there isn't, since
-most of the implementation details are delegated to the subsequent
-RFCs.
+@item mm-inline-media-tests
+This is an alist where the key is a @sc{mime} type, the second element
+is a function to display the part @dfn{inline} (i.e., inside Emacs), and
+the third element is a form to be @code{eval}ed to say whether the part
+can be displayed inline.
-So @file{rfc2045.el} has only a single function:
+This variable specifies whether a part @emph{can} be displayed inline,
+and, if so, how to do it. It does not say whether parts are
+@emph{actually} displayed inline.
-@table @code
-@item rfc2045-encode-string
-@findex rfc2045-encode-string
-Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
-@var{value} will be quoted if there are non-safe characters in it.
-@end table
+@item mm-inlined-types
+This, on the other hand, says what types are to be displayed inline, if
+they satisfy the conditions set by the variable above. It's a list of
+@sc{mime} media types.
+@item mm-automatic-display
+This is a list of types that are to be displayed ``automatically'', but
+only if the above variable allows it. That is, only inlinable parts can
+be displayed automatically.
-@node rfc2231
-@section rfc2231
+@item mm-attachment-override-types
+Some @sc{mime} agents create parts that have a content-disposition of
+@samp{attachment}. This variable allows overriding that disposition and
+displaying the part inline. (Note that the disposition is only
+overridden if we are able to, and want to, display the part inline.)
-RFC2231 defines a syntax for the @code{Content-Type} and
-@code{Content-Disposition} headers. Its snappy name is @dfn{MIME
-Parameter Value and Encoded Word Extensions: Character Sets, Languages,
-and Continuations}.
+@item mm-discouraged-alternatives
+List of @sc{mime} types that are discouraged when viewing
+@samp{multipart/alternative}. Viewing agents are supposed to view the
+last possible part of a message, as that is supposed to be the richest.
+However, users may prefer other types instead, and this list says what
+types are most unwanted. If, for instance, @samp{text/html} parts are
+very unwanted, and @samp{text/richtech} parts are somewhat unwanted,
+you could say something like:
-In short, these headers look something like this:
+@lisp
+(setq mm-discouraged-alternatives
+ '("text/html" "text/richtext")
+ mm-automatic-display
+ (remove "text/html" mm-automatic-display))
+@end lisp
-@example
-Content-Type: application/x-stuff;
- title*0*=us-ascii'en'This%20is%20even%20more%20;
- title*1*=%2A%2A%2Afun%2A%2A%2A%20;
- title*2="isn't it!"
-@end example
+@item mm-inline-large-images-p
+When displaying inline images that are larger than the window, XEmacs
+does not enable scrolling, which means that you cannot see the whole
+image. To prevent this, the library tries to determine the image size
+before displaying it inline, and if it doesn't fit the window, the
+library will display it externally (e.g. with @samp{ImageMagick} or
+@samp{xv}). Setting this variable to @code{t} disables this check and
+makes the library display all inline images as inline, regardless of
+their size.
-They usually aren't this bad, though.
+@item mm-inline-override-type
+@code{mm-inlined-types} may include regular expressions, for example to
+specify that all @samp{text/.*} parts be displayed inline. If a user
+prefers to have a type that matches such a regular expression be treated
+as an attachment, that can be accomplished by setting this variable to a
+list containing that type. For example assuming @code{mm-inlined-types}
+includes @samp{text/.*}, then including @samp{text/html} in this
+variable will cause @samp{text/html} parts to be treated as attachments.
-The following functions are defined by this library:
+@item mm-inline-text-html-renderer
+This selects the function used to render @sc{html}. The predefined
+renderers are selected by the symbols @code{w3},
+@code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
+information about emacs-w3m}, @code{links}, @code{lynx} or
+@code{html2text}. You can also specify a function, which will be
+called with a @sc{mime} handle as the argument.
-@table @code
-@item rfc2231-parse-string
-@findex rfc2231-parse-string
-Parse a @code{Content-Type} header and return a list describing its
-elements.
+@item mm-inline-text-html-with-images
+Some @sc{html} mails might have the trick of spammers using
+@samp{<img>} tags. It is likely to be intended to verify whether you
+have read the mail. You can prevent your personal informations from
+leaking by setting this option to @code{nil} (which is the default).
+It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
+command @kbd{t} on the image anchor to show an image even if it is
+@code{nil}.@footnote{The command @kbd{T} will load all images. If you
+have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
+or @kbd{I} instead.}
-@example
-(rfc2231-parse-string
- "application/x-stuff;
- title*0*=us-ascii'en'This%20is%20even%20more%20;
- title*1*=%2A%2A%2Afun%2A%2A%2A%20;
- title*2=\"isn't it!\"")
-@result{} ("application/x-stuff"
- (title . "This is even more ***fun*** isn't it!"))
-@end example
+@item mm-inline-text-html-with-w3m-keymap
+You can use emacs-w3m command keys in the inlined text/html part by
+setting this option to non-@code{nil}. The default value is @code{t}.
-@item rfc2231-get-value
-@findex rfc2231-get-value
-Takes one of the lists on the format above and returns
-the value of the specified attribute.
+@end table
-@item rfc2231-encode-string
-@findex rfc2231-encode-string
-Encode a parameter in headers likes @code{Content-Type} and
-@code{Content-Disposition}.
-@end table
+@node New Viewers
+@section New Viewers
+Here's an example viewer for displaying @code{text/enriched} inline:
-@node ietf-drums
-@section ietf-drums
+@lisp
+(defun mm-display-enriched-inline (handle)
+ (let (text)
+ (with-temp-buffer
+ (mm-insert-part handle)
+ (save-window-excursion
+ (enriched-decode (point-min) (point-max))
+ (setq text (buffer-string))))
+ (mm-insert-inline handle text)))
+@end lisp
-@dfn{drums} is an IETF working group that is working on the replacement
-for RFC822.
+We see that the function takes a @sc{mime} handle as its parameter. It
+then goes to a temporary buffer, inserts the text of the part, does some
+work on the text, stores the result, goes back to the buffer it was
+called from and inserts the result.
-The functions provided by this library include:
+The two important helper functions here are @code{mm-insert-part} and
+@code{mm-insert-inline}. The first function inserts the text of the
+handle in the current buffer. It handles charset and/or content
+transfer decoding. The second function just inserts whatever text you
+tell it to insert, but it also sets things up so that the text can be
+``undisplayed' in a convenient manner.
-@table @code
-@item ietf-drums-remove-comments
-@findex ietf-drums-remove-comments
-Remove the comments from the argument and return the results.
-@item ietf-drums-remove-whitespace
-@findex ietf-drums-remove-whitespace
-Remove linear white space from the string and return the results.
-Spaces inside quoted strings and comments are left untouched.
+@node Composing
+@chapter Composing
+@cindex Composing
+@cindex MIME Composing
+@cindex MML
+@cindex MIME Meta Language
-@item ietf-drums-get-comment
-@findex ietf-drums-get-comment
-Return the last most comment from the string.
+Creating a @sc{mime} message is boring and non-trivial. Therefore, a
+library called @code{mml} has been defined that parses a language called
+MML (@sc{mime} Meta Language) and generates @sc{mime} messages.
-@item ietf-drums-parse-address
-@findex ietf-drums-parse-address
-Parse an address string and return a list that contains the mailbox and
-the plain text name.
+@findex mml-generate-mime
+The main interface function is @code{mml-generate-mime}. It will
+examine the contents of the current (narrowed-to) buffer and return a
+string containing the @sc{mime} message.
-@item ietf-drums-parse-addresses
-@findex ietf-drums-parse-addresses
-Parse a string that contains any number of comma-separated addresses and
-return a list that contains mailbox/plain text pairs.
+@menu
+* Simple MML Example:: An example MML document.
+* MML Definition:: All valid MML elements.
+* Advanced MML Example:: Another example MML document.
+* Encoding Customization:: Variables that affect encoding.
+* Charset Translation:: How charsets are mapped from @sc{mule} to @sc{mime}.
+* Conversion:: Going from @sc{mime} to MML and vice versa.
+* Flowed text:: Soft and hard newlines.
+@end menu
-@item ietf-drums-parse-date
-@findex ietf-drums-parse-date
-Parse a date string and return an Emacs time structure.
-@item ietf-drums-narrow-to-header
-@findex ietf-drums-narrow-to-header
-Narrow the buffer to the header section of the current buffer.
+@node Simple MML Example
+@section Simple MML Example
-@end table
+Here's a simple @samp{multipart/alternative}:
+@example
+<#multipart type=alternative>
+This is a plain text part.
+<#part type=text/enriched>
+<center>This is a centered enriched part</center>
+<#/multipart>
+@end example
-@node rfc2047
-@section rfc2047
+After running this through @code{mml-generate-mime}, we get this:
-RFC2047 (Message Header Extensions for Non-ASCII Text) specifies how
-non-ASCII text in headers are to be encoded. This is actually rather
-complicated, so a number of variables are necessary to tweak what this
-library does.
+@example
+Content-Type: multipart/alternative; boundary="=-=-="
-The following variables are tweakable:
-@table @code
-@item rfc2047-default-charset
-@vindex rfc2047-default-charset
-Characters in this charset should not be decoded by this library.
-This defaults to @code{iso-8859-1}.
+--=-=-=
-@item rfc2047-header-encoding-list
-@vindex rfc2047-header-encoding-list
-This is an alist of header / encoding-type pairs. Its main purpose is
-to prevent encoding of certain headers.
-The keys can either be header regexps, or @code{t}.
+This is a plain text part.
-The values can be either @code{nil}, in which case the header(s) in
-question won't be encoded, or @code{mime}, which means that they will be
-encoded.
+--=-=-=
+Content-Type: text/enriched
-@item rfc2047-charset-encoding-alist
-@vindex rfc2047-charset-encoding-alist
-RFC2047 specifies two forms of encoding---@code{Q} (a
-Quoted-Printable-like encoding) and @code{B} (base64). This alist
-specifies which charset should use which encoding.
-@item rfc2047-encoding-function-alist
-@vindex rfc2047-encoding-function-alist
-This is an alist of encoding / function pairs. The encodings are
-@code{Q}, @code{B} and @code{nil}.
+<center>This is a centered enriched part</center>
-@item rfc2047-q-encoding-alist
-@vindex rfc2047-q-encoding-alist
-The @code{Q} encoding isn't quite the same for all headers. Some
-headers allow a narrower range of characters, and that is what this
-variable is for. It's an alist of header regexps / allowable character
-ranges.
+--=-=-=--
+@end example
-@item rfc2047-encoded-word-regexp
-@vindex rfc2047-encoded-word-regexp
-When decoding words, this library looks for matches to this regexp.
-@end table
+@node MML Definition
+@section MML Definition
-Those were the variables, and these are this functions:
+The MML language is very simple. It looks a bit like an SGML
+application, but it's not.
-@table @code
-@item rfc2047-narrow-to-field
-@findex rfc2047-narrow-to-field
-Narrow the buffer to the header on the current line.
+The main concept of MML is the @dfn{part}. Each part can be of a
+different type or use a different charset. The way to delineate a part
+is with a @samp{<#part ...>} tag. Multipart parts can be introduced
+with the @samp{<#multipart ...>} tag. Parts are ended by the
+@samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
+@samp{<#part ...>} tags are also closed by the next open tag.
-@item rfc2047-encode-message-header
-@findex rfc2047-encode-message-header
-Should be called narrowed to the header of a message. Encodes according
-to @code{rfc2047-header-encoding-alist}.
+There's also the @samp{<#external ...>} tag. These introduce
+@samp{external/message-body} parts.
-@item rfc2047-encode-region
-@findex rfc2047-encode-region
-Encodes all encodable words in the region specified.
+Each tag can contain zero or more parameters on the form
+@samp{parameter=value}. The values may be enclosed in quotation marks,
+but that's not necessary unless the value contains white space. So
+@samp{filename=/home/user/#hello$^yes} is perfectly valid.
-@item rfc2047-encode-string
-@findex rfc2047-encode-string
-Encode a string and return the results.
+The following parameters have meaning in MML; parameters that have no
+meaning are ignored. The MML parameter names are the same as the
+@sc{mime} parameter names; the things in the parentheses say which
+header it will be used in.
-@item rfc2047-decode-region
-@findex rfc2047-decode-region
-Decode the encoded words in the region.
+@table @samp
+@item type
+The @sc{mime} type of the part (@code{Content-Type}).
-@item rfc2047-decode-string
-@findex rfc2047-decode-string
-Decode a string and return the results.
+@item filename
+Use the contents of the file in the body of the part
+(@code{Content-Disposition}).
-@end table
+@item charset
+The contents of the body of the part are to be encoded in the character
+set speficied (@code{Content-Type}). @xref{Charset Translation}.
+@item name
+Might be used to suggest a file name if the part is to be saved
+to a file (@code{Content-Type}).
-@node time-date
-@section time-date
+@item disposition
+Valid values are @samp{inline} and @samp{attachment}
+(@code{Content-Disposition}).
-While not really a part of the @sc{mime} library, it is convenient to
-document this library here. It deals with parsing @code{Date} headers
-and manipulating time. (Not by using tesseracts, though, I'm sorry to
-say.)
+@item encoding
+Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
+@samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
+Translation}.
-These functions convert between five formats: A date string, an Emacs
-time structure, a decoded time list, a second number, and a day number.
+@item description
+A description of the part (@code{Content-Description}).
-Here's a bunch of time/date/second/day examples:
+@item creation-date
+RFC822 date when the part was created (@code{Content-Disposition}).
-@example
-(parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
-@result{} (54 21 12 12 9 1998 6 nil 7200)
+@item modification-date
+RFC822 date when the part was modified (@code{Content-Disposition}).
-(date-to-time "Sat Sep 12 12:21:54 1998 +0200")
-@result{} (13818 19266)
+@item read-date
+RFC822 date when the part was read (@code{Content-Disposition}).
-(time-to-seconds '(13818 19266))
-@result{} 905595714.0
+@item recipients
+Who to encrypt/sign the part to. This field is used to override any
+auto-detection based on the To/CC headers.
-(seconds-to-time 905595714.0)
-@result{} (13818 19266 0)
+@item size
+The size (in octets) of the part (@code{Content-Disposition}).
-(time-to-days '(13818 19266))
-@result{} 729644
+@item sign
+What technology to sign this MML part with (@code{smime}, @code{pgp}
+or @code{pgpmime})
-(days-to-time 729644)
-@result{} (961933 65536)
+@item encrypt
+What technology to encrypt this MML part with (@code{smime},
+@code{pgp} or @code{pgpmime})
-(time-since '(13818 19266))
-@result{} (0 430)
+@end table
-(time-less-p '(13818 19266) '(13818 19145))
-@result{} nil
+Parameters for @samp{application/octet-stream}:
-(subtract-time '(13818 19266) '(13818 19145))
-@result{} (0 121)
+@table @samp
+@item type
+Type of the part; informal---meant for human readers
+(@code{Content-Type}).
+@end table
-(days-between "Sat Sep 12 12:21:54 1998 +0200"
- "Sat Sep 07 12:21:54 1998 +0200")
-@result{} 5
+Parameters for @samp{message/external-body}:
-(date-leap-year-p 2000)
-@result{} t
+@table @samp
+@item access-type
+A word indicating the supported access mechanism by which the file may
+be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
+@samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
-(time-to-day-in-year '(13818 19266))
-@result{} 255
+@item expiration
+The RFC822 date after which the file may no longer be fetched.
+(@code{Content-Type}.)
-(time-to-number-of-days
- (time-since
- (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
-@result{} 4.146122685185185
-@end example
+@item size
+The size (in octets) of the file. (@code{Content-Type}.)
-And finally, we have @code{safe-date-to-time}, which does the same as
-@code{date-to-time}, but returns a zero time if the date is
-syntactically malformed.
+@item permission
+Valid values are @samp{read} and @samp{read-write}
+(@code{Content-Type}).
-The five data representations used are the following:
+@end table
-@table @var
-@item date
-An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
-12:21:54 1998 +0200"}.
+Parameters for @samp{sign=smime}:
-@item time
-An internal Emacs time. For instance: @code{(13818 26466)}.
+@table @samp
-@item seconds
-A floating point representation of the internal Emacs time. For
-instance: @code{905595714.0}.
+@item keyfile
+File containing key and certificate for signer.
-@item days
-An integer number representing the number of days since 00000101. For
-instance: @code{729644}.
+@end table
+
+Parameters for @samp{encrypt=smime}:
+
+@table @samp
+
+@item certfile
+File containing certificate for recipient.
-@item decoded time
-A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
-7200)}.
@end table
-All the examples above represent the same moment.
-These are the functions available:
+@node Advanced MML Example
+@section Advanced MML Example
+
+Here's a complex multipart message. It's a @samp{multipart/mixed} that
+contains many parts, one of which is a @samp{multipart/alternative}.
+
+@example
+<#multipart type=mixed>
+<#part type=image/jpeg filename=~/rms.jpg disposition=inline>
+<#multipart type=alternative>
+This is a plain text part.
+<#part type=text/enriched name=enriched.txt>
+<center>This is a centered enriched part</center>
+<#/multipart>
+This is a new plain text part.
+<#part disposition=attachment>
+This plain text part is an attachment.
+<#/multipart>
+@end example
+
+And this is the resulting @sc{mime} message:
+
+@example
+Content-Type: multipart/mixed; boundary="=-=-="
+
+
+--=-=-=
-@table @code
-@item date-to-time
-Take a date and return a time.
-@item time-to-seconds
-Take a time and return seconds.
-@item seconds-to-time
-Take seconds and return a time.
+--=-=-=
+Content-Type: image/jpeg;
+ filename="~/rms.jpg"
+Content-Disposition: inline;
+ filename="~/rms.jpg"
+Content-Transfer-Encoding: base64
-@item time-to-days
-Take a time and return days.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-@item days-to-time
-Take days and return a time.
+--=-=-=
+Content-Type: multipart/alternative; boundary="==-=-="
-@item date-to-day
-Take a date and return days.
-@item time-to-number-of-days
-Take a time and return the number of days that represents.
+--==-=-=
-@item safe-date-to-time
-Take a date and return a time. If the date is not syntactically valid,
-return a "zero" date.
-@item time-less-p
-Take two times and say whether the first time is less (i. e., earlier)
-than the second time.
+This is a plain text part.
-@item time-since
-Take a time and return a time saying how long it was since that time.
+--==-=-=
+Content-Type: text/enriched;
+ name="enriched.txt"
-@item subtract-time
-Take two times and subtract the second from the first. I. e., return
-the time between the two times.
-@item days-between
-Take two days and return the number of days between those two days.
+<center>This is a centered enriched part</center>
-@item date-leap-year-p
-Take a year number and say whether it's a leap year.
+--==-=-=--
-@item time-to-day-in-year
-Take a time and return the day number within the year that the time is
-in.
+--=-=-=
-@end table
+This is a new plain text part.
+--=-=-=
+Content-Disposition: attachment
-@node qp
-@section qp
-This library deals with decoding and encoding Quoted-Printable text.
+This plain text part is an attachment.
-Very briefly explained, qp encoding means translating all 8-bit
-characters (and lots of control characters) into things that look like
-@samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
-string.
+--=-=-=--
+@end example
-The following functions are defined by the library:
+@node Encoding Customization
+@section Encoding Customization
@table @code
-@item quoted-printable-decode-region
-@findex quoted-printable-decode-region
-QP-decode all the encoded text in the specified region.
-@item quoted-printable-decode-string
-@findex quoted-printable-decode-string
-Decode the QP-encoded text in a string and return the results.
+@item mm-body-charset-encoding-alist
+@vindex mm-body-charset-encoding-alist
+Mapping from MIME charset to encoding to use. This variable is
+usually used except, e.g., when other requirements force a specific
+encoding (digitally signed messages require 7bit encodings). The
+default is @code{((iso-2022-jp . 7bit) (iso-2022-jp-2 . 7bit))}. As
+an example, if you do not want to have ISO-8859-1 characters
+quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
+this variable. You can override this setting on a per-message basis
+by using the @code{encoding} MML tag (@pxref{MML Definition}).
+
+@item mm-coding-system-priorities
+@vindex mm-coding-system-priorities
+Prioritize coding systems to use for outgoing messages. The default
+is nil, which means to use the defaults in Emacs. It is a list of
+coding system symbols (aliases of coding systems does not work, use
+@kbd{M-x describe-coding-system} to make sure you are not specifying
+an alias in this variable). For example, if you have configured Emacs
+to use prefer UTF-8, but wish that outgoing messages should be sent in
+ISO-8859-1 if possible, you can set this variable to
+@code{(iso-latin-1)}. You can override this setting on a per-message
+basis by using the @code{charset} MML tag (@pxref{MML Definition}).
+
+@item mm-content-transfer-encoding-defaults
+@vindex mm-content-transfer-encoding-defaults
+Mapping from MIME types to encoding to use. This variable is usually
+used except, e.g., when other requirements force a safer encoding
+(digitally signed messages require 7bit encoding). Besides the normal
+MIME encodings, @code{qp-or-base64} may be used to indicate that for
+each case the most efficient of quoted-printable and base64 should be
+used. You can override this setting on a per-message basis by using
+the @code{encoding} MML tag (@pxref{MML Definition}).
+
+@item mm-use-ultra-safe-encoding
+@vindex mm-use-ultra-safe-encoding
+When this is non-nil, it means that textual parts are encoded as
+quoted-printable if they contain lines longer than 76 characters or
+starting with "From " in the body. Non-7bit encodings (8bit, binary)
+are generally disallowed. This reduce the probability that a non-8bit
+clean MTA or MDA changes the message. This should never be set
+directly, but bound by other functions when necessary (e.g., when
+encoding messages that are to be digitally signed).
-@item quoted-printable-encode-region
-@findex quoted-printable-encode-region
-QP-encode all the encodable characters in the specified region. The third
-optional parameter @var{fold} specifies whether to fold long lines.
-(Long here means 72.)
+@end table
-@item quoted-printable-encode-string
-@findex quoted-printable-encode-string
-QP-encode all the encodable characters in a string and return the
-results.
+@node Charset Translation
+@section Charset Translation
+@cindex charsets
-@end table
+During translation from MML to @sc{mime}, for each @sc{mime} part which
+has been composed inside Emacs, an appropriate charset has to be chosen.
+@vindex mail-parse-charset
+If you are running a non-@sc{mule} Emacs, this process is simple: If the
+part contains any non-ASCII (8-bit) characters, the @sc{mime} charset
+given by @code{mail-parse-charset} (a symbol) is used. (Never set this
+variable directly, though. If you want to change the default charset,
+please consult the documentation of the package which you use to process
+@sc{mime} messages.
+@xref{Various Message Variables, , Various Message Variables, message,
+ Message Manual}, for example.)
+If there are only ASCII characters, the @sc{mime} charset US-ASCII is
+used, of course.
-@node base64
-@section base64
-@cindex base64
+@cindex MULE
+@cindex UTF-8
+@cindex Unicode
+@vindex mm-mime-mule-charset-alist
+Things are slightly more complicated when running Emacs with @sc{mule}
+support. In this case, a list of the @sc{mule} charsets used in the
+part is obtained, and the @sc{mule} charsets are translated to @sc{mime}
+charsets by consulting the variable @code{mm-mime-mule-charset-alist}.
+If this results in a single @sc{mime} charset, this is used to encode
+the part. But if the resulting list of @sc{mime} charsets contains more
+than one element, two things can happen: If it is possible to encode the
+part via UTF-8, this charset is used. (For this, Emacs must support
+the @code{utf-8} coding system, and the part must consist entirely of
+characters which have Unicode counterparts.) If UTF-8 is not available
+for some reason, the part is split into several ones, so that each one
+can be encoded with a single @sc{mime} charset. The part can only be
+split at line boundaries, though---if more than one @sc{mime} charset is
+required to encode a single line, it is not possible to encode the part.
-Base64 is an encoding that encodes three bytes into four characters,
-thereby increasing the size by about 33%. The alphabet used for
-encoding is very resistant to mangling during transit.
+When running Emacs with @sc{mule} support, the preferences for which
+coding system to use is inherited from Emacs itself. This means that
+if Emacs is set up to prefer UTF-8, it will be used when encoding
+messages. You can modify this by altering the
+@code{mm-coding-system-priorities} variable though (@pxref{Encoding
+Customization}).
-The following functions are defined by this library:
+The charset to be used can be overriden by setting the @code{charset}
+MML tag (@pxref{MML Definition}) when composing the message.
-@table @code
-@item base64-encode-region
-@findex base64-encode-region
-base64 encode the selected region. Return the length of the encoded
-text. Optional third argument @var{no-line-break} means do not break
-long lines into shorter lines.
+The encoding of characters (quoted-printable, 8bit etc) is orthogonal
+to the discussion here, and is controlled by the variables
+@code{mm-body-charset-encoding-alist} and
+@code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
+Customization}).
-@item base64-encode-string
-@findex base64-encode-string
-base64 encode a string and return the result.
+@node Conversion
+@section Conversion
-@item base64-decode-region
-@findex base64-decode-region
-base64 decode the selected region. Return the length of the decoded
-text. If the region can't be decoded, return @code{nil} and don't
-modify the buffer.
+@findex mime-to-mml
+A (multipart) @sc{mime} message can be converted to MML with the
+@code{mime-to-mml} function. It works on the message in the current
+buffer, and substitutes MML markup for @sc{mime} boundaries.
+Non-textual parts do not have their contents in the buffer, but instead
+have the contents in separate buffers that are referred to from the MML
+tags.
-@item base64-decode-string
-@findex base64-decode-string
-base64 decode a string and return the result. If the string can't be
-decoded, @code{nil} is returned.
+@findex mml-to-mime
+An MML message can be converted back to @sc{mime} by the
+@code{mml-to-mime} function.
-@end table
+These functions are in certain senses ``lossy''---you will not get back
+an identical message if you run @sc{mime-to-mml} and then
+@sc{mml-to-mime}. Not only will trivial things like the order of the
+headers differ, but the contents of the headers may also be different.
+For instance, the original message may use base64 encoding on text,
+while @sc{mml-to-mime} may decide to use quoted-printable encoding, and
+so on.
+In essence, however, these two functions should be the inverse of each
+other. The resulting contents of the message should remain equivalent,
+if not identical.
-@node binhex
-@section binhex
-@cindex binhex
-@cindex Apple
-@cindex Macintosh
-@code{binhex} is an encoding that originated in Macintosh environments.
-The following function is supplied to deal with these:
+@node Flowed text
+@section Flowed text
+@cindex format=flowed
-@table @code
-@item binhex-decode-region
-@findex binhex-decode-region
-Decode the encoded text in the region. If given a third parameter, only
-decode the @code{binhex} header and return the filename.
+The Emacs @sc{mime} library will respect the @code{use-hard-newlines}
+variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
+emacs, Emacs Manual}) when encoding a message, and the
+``format=flowed'' Content-Type parameter when decoding a message.
-@end table
+On encoding text, lines terminated by soft newline characters are
+filled together and wrapped after the column decided by
+@code{fill-flowed-encode-column}. This variable controls how the text
+will look in a client that does not support flowed text, the default
+is to wrap after 66 characters. If hard newline characters are not
+present in the buffer, no flow encoding occurs.
+On decoding flowed text, lines with soft newline characters are filled
+together and wrapped after the column decided by
+@code{fill-flowed-display-column}. The default is to wrap after
+@code{fill-column}.
-@node uudecode
-@section uudecode
-@cindex uuencode
-@cindex uudecode
-@code{uuencode} is probably still the most popular encoding of binaries
-used on Usenet, although @code{base64} rules the mail world.
-The following function is supplied by this package:
-@table @code
-@item uudecode-decode-region
-@findex uudecode-decode-region
-Decode the text in the region.
-@end table
+@node Interface Functions
+@chapter Interface Functions
+@cindex interface functions
+@cindex mail-parse
+
+The @code{mail-parse} library is an abstraction over the actual
+low-level libraries that are described in the next chapter.
+
+Standards change, and so programs have to change to fit in the new
+mold. For instance, RFC2045 describes a syntax for the
+@code{Content-Type} header that only allows ASCII characters in the
+parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
+for continuation headers and non-ASCII characters.
+
+The traditional way to deal with this is just to update the library
+functions to parse the new syntax. However, this is sometimes the wrong
+thing to do. In some instances it may be vital to be able to understand
+both the old syntax as well as the new syntax, and if there is only one
+library, one must choose between the old version of the library and the
+new version of the library.
+
+The Emacs @sc{mime} library takes a different tack. It defines a
+series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
+and so on) that parses strictly according to the corresponding
+standard. However, normal programs would not use the functions
+provided by these libraries directly, but instead use the functions
+provided by the @code{mail-parse} library. The functions in this
+library are just aliases to the corresponding functions in the latest
+low-level libraries. Using this scheme, programs get a consistent
+interface they can use, and library developers are free to create
+write code that handles new standards.
+The following functions are defined by this library:
-@node rfc1843
-@section rfc1843
-@cindex rfc1843
-@cindex HZ
-@cindex Chinese
+@table @code
+@item mail-header-parse-content-type
+@findex mail-header-parse-content-type
+Parse a @code{Content-Type} header and return a list on the following
+format:
-RFC1843 deals with mixing Chinese and ASCII characters in messages. In
-essence, RFC1843 switches between ASCII and Chinese by doing this:
+@lisp
+("type/subtype"
+ (attribute1 . value1)
+ (attribute2 . value2)
+ ...)
+@end lisp
+
+Here's an example:
@example
-This sentence is in ASCII.
-The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
+(mail-header-parse-content-type
+ "image/gif; name=\"b980912.gif\"")
+@result{} ("image/gif" (name . "b980912.gif"))
@end example
-Simple enough, and widely used in China.
-
-The following functions are available to handle this encoding:
+@item mail-header-parse-content-disposition
+@findex mail-header-parse-content-disposition
+Parse a @code{Content-Disposition} header and return a list on the same
+format as the function above.
-@table @code
-@item rfc1843-decode-region
-Decode HZ-encoded text in the region.
+@item mail-content-type-get
+@findex mail-content-type-get
+Takes two parameters---a list on the format above, and an attribute.
+Returns the value of the attribute.
-@item rfc1843-decode-string
-Decode a HZ-encoded string and return the result.
+@example
+(mail-content-type-get
+ '("image/gif" (name . "b980912.gif")) 'name)
+@result{} "b980912.gif"
+@end example
-@end table
+@item mail-header-encode-parameter
+@findex mail-header-encode-parameter
+Takes a parameter string and returns an encoded version of the string.
+This is used for parameters in headers like @code{Content-Type} and
+@code{Content-Disposition}.
+@item mail-header-remove-comments
+@findex mail-header-remove-comments
+Return a comment-free version of a header.
-@node mailcap
-@section mailcap
+@example
+(mail-header-remove-comments
+ "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
+@result{} "Gnus/5.070027 "
+@end example
-The @file{~/.mailcap} file is parsed by most @sc{mime}-aware message
-handlers and describes how elements are supposed to be displayed.
-Here's an example file:
+@item mail-header-remove-whitespace
+@findex mail-header-remove-whitespace
+Remove linear white space from a header. Space inside quoted strings
+and comments is preserved.
@example
-image/*; gimp -8 %s
-audio/wav; wavplayer %s
-application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
+(mail-header-remove-whitespace
+ "image/gif; name=\"Name with spaces\"")
+@result{} "image/gif;name=\"Name with spaces\""
@end example
-This says that all image files should be displayed with @code{gimp},
-that WAVE audio files should be played by @code{wavplayer}, and that
-MS-WORD files should be inlined by @code{catdoc}.
-
-The @code{mailcap} library parses this file, and provides functions for
-matching types.
+@item mail-header-get-comment
+@findex mail-header-get-comment
+Return the last comment in a header.
-@table @code
-@item mailcap-mime-data
-@vindex mailcap-mime-data
-This variable is an alist of alists containing backup viewing rules.
+@example
+(mail-header-get-comment
+ "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
+@result{} "Finnish Landrace"
+@end example
-@end table
+@item mail-header-parse-address
+@findex mail-header-parse-address
+Parse an address and return a list containing the mailbox and the
+plaintext name.
-Interface functions:
+@example
+(mail-header-parse-address
+ "Hrvoje Niksic <hniksic@@srce.hr>")
+@result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
+@end example
-@table @code
-@item mailcap-parse-mailcaps
-@findex mailcap-parse-mailcaps
-Parse the @code{~/.mailcap} file.
+@item mail-header-parse-addresses
+@findex mail-header-parse-addresses
+Parse a string with list of addresses and return a list of elements like
+the one described above.
-@item mailcap-mime-info
-Takes a @sc{mime} type as its argument and returns the matching viewer.
+@example
+(mail-header-parse-addresses
+ "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
+@result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
+ ("sb@@metis.no" . "Steinar Bang"))
+@end example
-@end table
+@item mail-header-parse-date
+@findex mail-header-parse-date
+Parse a date string and return an Emacs time structure.
+@item mail-narrow-to-head
+@findex mail-narrow-to-head
+Narrow the buffer to the header section of the buffer. Point is placed
+at the beginning of the narrowed buffer.
+@item mail-header-narrow-to-field
+@findex mail-header-narrow-to-field
+Narrow the buffer to the header under point. Understands continuation
+headers.
+@item mail-header-fold-field
+@findex mail-header-fold-field
+Fold the header under point.
-@node Decoding and Viewing
-@chapter Decoding and Viewing
+@item mail-header-unfold-field
+@findex mail-header-unfold-field
+Unfold the header under point.
-This chapter deals with decoding and viewing @sc{mime} messages on a
-higher level.
+@item mail-header-field-value
+@findex mail-header-field-value
+Return the value of the field under point.
-The main idea is to first analyze a @sc{mime} article, and then allow
-other programs to do things based on the list of @dfn{handles} that are
-returned as a result of this analysis.
+@item mail-encode-encoded-word-region
+@findex mail-encode-encoded-word-region
+Encode the non-ASCII words in the region. For instance,
+@samp{Naïve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
-@menu
-* Dissection:: Analyzing a @sc{mime} message.
-* Non-MIME:: Analyzing a non-@sc{mime} message.
-* Handles:: Handle manipulations.
-* Display:: Displaying handles.
-* Customization:: Variables that affect display.
-* New Viewers:: How to write your own viewers.
-@end menu
+@item mail-encode-encoded-word-buffer
+@findex mail-encode-encoded-word-buffer
+Encode the non-ASCII words in the current buffer. This function is
+meant to be called narrowed to the headers of a message.
+@item mail-encode-encoded-word-string
+@findex mail-encode-encoded-word-string
+Encode the words that need encoding in a string, and return the result.
-@node Dissection
-@section Dissection
+@example
+(mail-encode-encoded-word-string
+ "This is naïve, baby")
+@result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
+@end example
-The @code{mm-dissect-buffer} is the function responsible for dissecting
-a @sc{mime} article. If given a multipart message, it will recursively
-descend the message, following the structure, and return a tree of
-@sc{mime} handles that describes the structure of the message.
+@item mail-decode-encoded-word-region
+@findex mail-decode-encoded-word-region
+Decode the encoded words in the region.
-@node Non-MIME
-@section Non-MIME
+@item mail-decode-encoded-word-string
+@findex mail-decode-encoded-word-string
+Decode the encoded words in the string and return the result.
-Gnus also understands some non-@sc{mime} attachments, such as
-postscript, uuencode, binhex, shar, forward, gnatsweb, pgp. Each of
-these features can be disabled by add an item into
-@code{mm-uu-configure-list}. For example,
+@example
+(mail-decode-encoded-word-string
+ "This is =?iso-8859-1?q?na=EFve,?= baby")
+@result{} "This is naïve, baby"
+@end example
-@lisp
-(require 'mm-uu)
-(add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
-@end lisp
+@end table
-@table @code
-@item postscript
-@findex postscript
-Postscript file.
+Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
+@code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
+in the subsequent sections.
-@item uu
-@findex uu
-Uuencoded file.
-@item binhex
-@findex binhex
-Binhex encoded file.
-@item shar
-@findex shar
-Shar archive file.
+@node Basic Functions
+@chapter Basic Functions
-@item forward
-@findex forward
-Non-@sc{mime} forwarded message.
+This chapter describes the basic, ground-level functions for parsing and
+handling. Covered here is parsing @code{From} lines, removing comments
+from header lines, decoding encoded words, parsing date headers and so
+on. High-level functionality is dealt with in the next chapter
+(@pxref{Decoding and Viewing}).
-@item gnatsweb
-@findex gnatsweb
-Gnatsweb attachment.
+@menu
+* rfc2045:: Encoding @code{Content-Type} headers.
+* rfc2231:: Parsing @code{Content-Type} headers.
+* ietf-drums:: Handling mail headers defined by RFC822bis.
+* rfc2047:: En/decoding encoded words in headers.
+* time-date:: Functions for parsing dates and manipulating time.
+* qp:: Quoted-Printable en/decoding.
+* base64:: Base64 en/decoding.
+* binhex:: Binhex decoding.
+* uudecode:: Uuencode decoding.
+* rfc1843:: Decoding HZ-encoded text.
+* mailcap:: How parts are displayed is specified by the @file{.mailcap} file
+@end menu
-@item pgp-signed
-@findex pgp-signed
-PGP signed clear text.
-@item pgp-encrypted
-@findex pgp-encrypted
-PGP encrypted clear text.
+@node rfc2045
+@section rfc2045
-@item pgp-key
-@findex pgp-key
-PGP public keys.
+RFC2045 is the ``main'' @sc{mime} document, and as such, one would
+imagine that there would be a lot to implement. But there isn't, since
+most of the implementation details are delegated to the subsequent
+RFCs.
-@item emacs-sources
-@findex emacs-sources
-Emacs source code. This item works only in the groups matching
-@code{mm-uu-emacs-sources-regexp}.
+So @file{rfc2045.el} has only a single function:
+@table @code
+@item rfc2045-encode-string
+@findex rfc2045-encode-string
+Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
+@var{value} will be quoted if there are non-safe characters in it.
@end table
-@node Handles
-@section Handles
-A @sc{mime} handle is a list that fully describes a @sc{mime}
-component.
+@node rfc2231
+@section rfc2231
-The following macros can be used to access elements in a handle:
+RFC2231 defines a syntax for the @code{Content-Type} and
+@code{Content-Disposition} headers. Its snappy name is @dfn{MIME
+Parameter Value and Encoded Word Extensions: Character Sets, Languages,
+and Continuations}.
-@table @code
-@item mm-handle-buffer
-@findex mm-handle-buffer
-Return the buffer that holds the contents of the undecoded @sc{mime}
-part.
+In short, these headers look something like this:
-@item mm-handle-type
-@findex mm-handle-type
-Return the parsed @code{Content-Type} of the part.
+@example
+Content-Type: application/x-stuff;
+ title*0*=us-ascii'en'This%20is%20even%20more%20;
+ title*1*=%2A%2A%2Afun%2A%2A%2A%20;
+ title*2="isn't it!"
+@end example
-@item mm-handle-encoding
-@findex mm-handle-encoding
-Return the @code{Content-Transfer-Encoding} of the part.
+They usually aren't this bad, though.
-@item mm-handle-undisplayer
-@findex mm-handle-undisplayer
-Return the object that can be used to remove the displayed part (if it
-has been displayed).
+The following functions are defined by this library:
-@item mm-handle-set-undisplayer
-@findex mm-handle-set-undisplayer
-Set the undisplayer object.
+@table @code
+@item rfc2231-parse-string
+@findex rfc2231-parse-string
+Parse a @code{Content-Type} header and return a list describing its
+elements.
-@item mm-handle-disposition
-@findex mm-handle-disposition
-Return the parsed @code{Content-Disposition} of the part.
+@example
+(rfc2231-parse-string
+ "application/x-stuff;
+ title*0*=us-ascii'en'This%20is%20even%20more%20;
+ title*1*=%2A%2A%2Afun%2A%2A%2A%20;
+ title*2=\"isn't it!\"")
+@result{} ("application/x-stuff"
+ (title . "This is even more ***fun*** isn't it!"))
+@end example
-@item mm-handle-disposition
-@findex mm-handle-disposition
-Return the description of the part.
+@item rfc2231-get-value
+@findex rfc2231-get-value
+Takes one of the lists on the format above and returns
+the value of the specified attribute.
-@item mm-get-content-id
-Returns the handle(s) referred to by @code{Content-ID}.
+@item rfc2231-encode-string
+@findex rfc2231-encode-string
+Encode a parameter in headers likes @code{Content-Type} and
+@code{Content-Disposition}.
@end table
-@node Display
-@section Display
+@node ietf-drums
+@section ietf-drums
-Functions for displaying, removing and saving.
+@dfn{drums} is an IETF working group that is working on the replacement
+for RFC822.
-@table @code
-@item mm-display-part
-@findex mm-display-part
-Display the part.
+The functions provided by this library include:
-@item mm-remove-part
-@findex mm-remove-part
-Remove the part (if it has been displayed).
+@table @code
+@item ietf-drums-remove-comments
+@findex ietf-drums-remove-comments
+Remove the comments from the argument and return the results.
-@item mm-inlinable-p
-@findex mm-inlinable-p
-Say whether a @sc{mime} type can be displayed inline.
+@item ietf-drums-remove-whitespace
+@findex ietf-drums-remove-whitespace
+Remove linear white space from the string and return the results.
+Spaces inside quoted strings and comments are left untouched.
-@item mm-automatic-display-p
-@findex mm-automatic-display-p
-Say whether a @sc{mime} type should be displayed automatically.
+@item ietf-drums-get-comment
+@findex ietf-drums-get-comment
+Return the last most comment from the string.
-@item mm-destroy-part
-@findex mm-destroy-part
-Free all resources occupied by a part.
+@item ietf-drums-parse-address
+@findex ietf-drums-parse-address
+Parse an address string and return a list that contains the mailbox and
+the plain text name.
-@item mm-save-part
-@findex mm-save-part
-Offer to save the part in a file.
+@item ietf-drums-parse-addresses
+@findex ietf-drums-parse-addresses
+Parse a string that contains any number of comma-separated addresses and
+return a list that contains mailbox/plain text pairs.
-@item mm-pipe-part
-@findex mm-pipe-part
-Offer to pipe the part to some process.
+@item ietf-drums-parse-date
+@findex ietf-drums-parse-date
+Parse a date string and return an Emacs time structure.
-@item mm-interactively-view-part
-@findex mm-interactively-view-part
-Prompt for a mailcap method to use to view the part.
+@item ietf-drums-narrow-to-header
+@findex ietf-drums-narrow-to-header
+Narrow the buffer to the header section of the current buffer.
@end table
-@node Customization
-@section Customization
-
-@table @code
-
-@item mm-inline-media-tests
-This is an alist where the key is a @sc{mime} type, the second element
-is a function to display the part @dfn{inline} (i.e., inside Emacs), and
-the third element is a form to be @code{eval}ed to say whether the part
-can be displayed inline.
-
-This variable specifies whether a part @emph{can} be displayed inline,
-and, if so, how to do it. It does not say whether parts are
-@emph{actually} displayed inline.
+@node rfc2047
+@section rfc2047
-@item mm-inlined-types
-This, on the other hand, says what types are to be displayed inline, if
-they satisfy the conditions set by the variable above. It's a list of
-@sc{mime} media types.
+RFC2047 (Message Header Extensions for Non-ASCII Text) specifies how
+non-ASCII text in headers are to be encoded. This is actually rather
+complicated, so a number of variables are necessary to tweak what this
+library does.
-@item mm-automatic-display
-This is a list of types that are to be displayed ``automatically'', but
-only if the above variable allows it. That is, only inlinable parts can
-be displayed automatically.
+The following variables are tweakable:
-@item mm-attachment-override-types
-Some @sc{mime} agents create parts that have a content-disposition of
-@samp{attachment}. This variable allows overriding that disposition and
-displaying the part inline. (Note that the disposition is only
-overridden if we are able to, and want to, display the part inline.)
+@table @code
+@item rfc2047-default-charset
+@vindex rfc2047-default-charset
+Characters in this charset should not be decoded by this library.
+This defaults to @code{iso-8859-1}.
-@item mm-discouraged-alternatives
-List of @sc{mime} types that are discouraged when viewing
-@samp{multipart/alternative}. Viewing agents are supposed to view the
-last possible part of a message, as that is supposed to be the richest.
-However, users may prefer other types instead, and this list says what
-types are most unwanted. If, for instance, @samp{text/html} parts are
-very unwanted, and @samp{text/richtech} parts are somewhat unwanted,
-you could say something like:
+@item rfc2047-header-encoding-list
+@vindex rfc2047-header-encoding-list
+This is an alist of header / encoding-type pairs. Its main purpose is
+to prevent encoding of certain headers.
-@lisp
-(setq mm-discouraged-alternatives
- '("text/html" "text/richtext")
- mm-automatic-display
- (remove "text/html" mm-automatic-display))
-@end lisp
+The keys can either be header regexps, or @code{t}.
-@item mm-inline-large-images-p
-When displaying inline images that are larger than the window, XEmacs
-does not enable scrolling, which means that you cannot see the whole
-image. To prevent this, the library tries to determine the image size
-before displaying it inline, and if it doesn't fit the window, the
-library will display it externally (e.g. with @samp{ImageMagick} or
-@samp{xv}). Setting this variable to @code{t} disables this check and
-makes the library display all inline images as inline, regardless of
-their size.
+The values can be either @code{nil}, in which case the header(s) in
+question won't be encoded, or @code{mime}, which means that they will be
+encoded.
-@item mm-inline-override-type
-@code{mm-inlined-types} may include regular expressions, for example to
-specify that all @samp{text/.*} parts be displayed inline. If a user
-prefers to have a type that matches such a regular expression be treated
-as an attachment, that can be accomplished by setting this variable to a
-list containing that type. For example assuming @code{mm-inlined-types}
-includes @samp{text/.*}, then including @samp{text/html} in this
-variable will cause @samp{text/html} parts to be treated as attachments.
+@item rfc2047-charset-encoding-alist
+@vindex rfc2047-charset-encoding-alist
+RFC2047 specifies two forms of encoding---@code{Q} (a
+Quoted-Printable-like encoding) and @code{B} (base64). This alist
+specifies which charset should use which encoding.
-@item mm-inline-text-html-renderer
-This selects the function used to render @sc{html}. The predefined
-renderers are selected by the symbols @code{w3},
-@code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
-information about emacs-w3m}, @code{links}, @code{lynx} or
-@code{html2text}. You can also specify a function, which will be
-called with a @sc{mime} handle as the argument.
+@item rfc2047-encoding-function-alist
+@vindex rfc2047-encoding-function-alist
+This is an alist of encoding / function pairs. The encodings are
+@code{Q}, @code{B} and @code{nil}.
-@item mm-inline-text-html-with-images
-Some @sc{html} mails might have the trick of spammers using
-@samp{<img>} tags. It is likely to be intended to verify whether you
-have read the mail. You can prevent your personal informations from
-leaking by setting this option to @code{nil} (which is the default).
-It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
-command @kbd{t} on the image anchor to show an image even if it is
-@code{nil}.@footnote{The command @kbd{T} will load all images. If you
-have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
-or @kbd{I} instead.}
+@item rfc2047-q-encoding-alist
+@vindex rfc2047-q-encoding-alist
+The @code{Q} encoding isn't quite the same for all headers. Some
+headers allow a narrower range of characters, and that is what this
+variable is for. It's an alist of header regexps / allowable character
+ranges.
-@item mm-inline-text-html-with-w3m-keymap
-You can use emacs-w3m command keys in the inlined text/html part by
-setting this option to non-@code{nil}. The default value is @code{t}.
+@item rfc2047-encoded-word-regexp
+@vindex rfc2047-encoded-word-regexp
+When decoding words, this library looks for matches to this regexp.
@end table
+Those were the variables, and these are this functions:
-@node New Viewers
-@section New Viewers
+@table @code
+@item rfc2047-narrow-to-field
+@findex rfc2047-narrow-to-field
+Narrow the buffer to the header on the current line.
+
+@item rfc2047-encode-message-header
+@findex rfc2047-encode-message-header
+Should be called narrowed to the header of a message. Encodes according
+to @code{rfc2047-header-encoding-alist}.
-Here's an example viewer for displaying @code{text/enriched} inline:
+@item rfc2047-encode-region
+@findex rfc2047-encode-region
+Encodes all encodable words in the region specified.
-@lisp
-(defun mm-display-enriched-inline (handle)
- (let (text)
- (with-temp-buffer
- (mm-insert-part handle)
- (save-window-excursion
- (enriched-decode (point-min) (point-max))
- (setq text (buffer-string))))
- (mm-insert-inline handle text)))
-@end lisp
+@item rfc2047-encode-string
+@findex rfc2047-encode-string
+Encode a string and return the results.
-We see that the function takes a @sc{mime} handle as its parameter. It
-then goes to a temporary buffer, inserts the text of the part, does some
-work on the text, stores the result, goes back to the buffer it was
-called from and inserts the result.
+@item rfc2047-decode-region
+@findex rfc2047-decode-region
+Decode the encoded words in the region.
-The two important helper functions here are @code{mm-insert-part} and
-@code{mm-insert-inline}. The first function inserts the text of the
-handle in the current buffer. It handles charset and/or content
-transfer decoding. The second function just inserts whatever text you
-tell it to insert, but it also sets things up so that the text can be
-``undisplayed' in a convenient manner.
+@item rfc2047-decode-string
+@findex rfc2047-decode-string
+Decode a string and return the results.
+@end table
-@node Composing
-@chapter Composing
-@cindex Composing
-@cindex MIME Composing
-@cindex MML
-@cindex MIME Meta Language
-Creating a @sc{mime} message is boring and non-trivial. Therefore, a
-library called @code{mml} has been defined that parses a language called
-MML (@sc{mime} Meta Language) and generates @sc{mime} messages.
+@node time-date
+@section time-date
-@findex mml-generate-mime
-The main interface function is @code{mml-generate-mime}. It will
-examine the contents of the current (narrowed-to) buffer and return a
-string containing the @sc{mime} message.
+While not really a part of the @sc{mime} library, it is convenient to
+document this library here. It deals with parsing @code{Date} headers
+and manipulating time. (Not by using tesseracts, though, I'm sorry to
+say.)
-@menu
-* Simple MML Example:: An example MML document.
-* MML Definition:: All valid MML elements.
-* Advanced MML Example:: Another example MML document.
-* Charset Translation:: How charsets are mapped from @sc{mule} to @sc{mime}.
-* Conversion:: Going from @sc{mime} to MML and vice versa.
-* Flowed text:: Soft and hard newlines.
-@end menu
+These functions convert between five formats: A date string, an Emacs
+time structure, a decoded time list, a second number, and a day number.
+Here's a bunch of time/date/second/day examples:
-@node Simple MML Example
-@section Simple MML Example
+@example
+(parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
+@result{} (54 21 12 12 9 1998 6 nil 7200)
-Here's a simple @samp{multipart/alternative}:
+(date-to-time "Sat Sep 12 12:21:54 1998 +0200")
+@result{} (13818 19266)
-@example
-<#multipart type=alternative>
-This is a plain text part.
-<#part type=text/enriched>
-<center>This is a centered enriched part</center>
-<#/multipart>
-@end example
+(time-to-seconds '(13818 19266))
+@result{} 905595714.0
-After running this through @code{mml-generate-mime}, we get this:
+(seconds-to-time 905595714.0)
+@result{} (13818 19266 0)
-@example
-Content-Type: multipart/alternative; boundary="=-=-="
+(time-to-days '(13818 19266))
+@result{} 729644
+(days-to-time 729644)
+@result{} (961933 65536)
---=-=-=
+(time-since '(13818 19266))
+@result{} (0 430)
+(time-less-p '(13818 19266) '(13818 19145))
+@result{} nil
-This is a plain text part.
+(subtract-time '(13818 19266) '(13818 19145))
+@result{} (0 121)
---=-=-=
-Content-Type: text/enriched
+(days-between "Sat Sep 12 12:21:54 1998 +0200"
+ "Sat Sep 07 12:21:54 1998 +0200")
+@result{} 5
+(date-leap-year-p 2000)
+@result{} t
-<center>This is a centered enriched part</center>
+(time-to-day-in-year '(13818 19266))
+@result{} 255
---=-=-=--
+(time-to-number-of-days
+ (time-since
+ (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
+@result{} 4.146122685185185
@end example
+And finally, we have @code{safe-date-to-time}, which does the same as
+@code{date-to-time}, but returns a zero time if the date is
+syntactically malformed.
-@node MML Definition
-@section MML Definition
+The five data representations used are the following:
-The MML language is very simple. It looks a bit like an SGML
-application, but it's not.
+@table @var
+@item date
+An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
+12:21:54 1998 +0200"}.
-The main concept of MML is the @dfn{part}. Each part can be of a
-different type or use a different charset. The way to delineate a part
-is with a @samp{<#part ...>} tag. Multipart parts can be introduced
-with the @samp{<#multipart ...>} tag. Parts are ended by the
-@samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
-@samp{<#part ...>} tags are also closed by the next open tag.
+@item time
+An internal Emacs time. For instance: @code{(13818 26466)}.
-There's also the @samp{<#external ...>} tag. These introduce
-@samp{external/message-body} parts.
+@item seconds
+A floating point representation of the internal Emacs time. For
+instance: @code{905595714.0}.
-Each tag can contain zero or more parameters on the form
-@samp{parameter=value}. The values may be enclosed in quotation marks,
-but that's not necessary unless the value contains white space. So
-@samp{filename=/home/user/#hello$^yes} is perfectly valid.
+@item days
+An integer number representing the number of days since 00000101. For
+instance: @code{729644}.
-The following parameters have meaning in MML; parameters that have no
-meaning are ignored. The MML parameter names are the same as the
-@sc{mime} parameter names; the things in the parentheses say which
-header it will be used in.
+@item decoded time
+A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
+7200)}.
+@end table
-@table @samp
-@item type
-The @sc{mime} type of the part (@code{Content-Type}).
+All the examples above represent the same moment.
-@item filename
-Use the contents of the file in the body of the part
-(@code{Content-Disposition}).
+These are the functions available:
-@item charset
-The contents of the body of the part are to be encoded in the character
-set speficied (@code{Content-Type}).
+@table @code
+@item date-to-time
+Take a date and return a time.
-@item name
-Might be used to suggest a file name if the part is to be saved
-to a file (@code{Content-Type}).
+@item time-to-seconds
+Take a time and return seconds.
-@item disposition
-Valid values are @samp{inline} and @samp{attachment}
-(@code{Content-Disposition}).
+@item seconds-to-time
+Take seconds and return a time.
-@item encoding
-Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
-@samp{base64} (@code{Content-Transfer-Encoding}).
+@item time-to-days
+Take a time and return days.
-@item description
-A description of the part (@code{Content-Description}).
+@item days-to-time
+Take days and return a time.
-@item creation-date
-RFC822 date when the part was created (@code{Content-Disposition}).
+@item date-to-day
+Take a date and return days.
-@item modification-date
-RFC822 date when the part was modified (@code{Content-Disposition}).
+@item time-to-number-of-days
+Take a time and return the number of days that represents.
-@item read-date
-RFC822 date when the part was read (@code{Content-Disposition}).
+@item safe-date-to-time
+Take a date and return a time. If the date is not syntactically valid,
+return a "zero" date.
-@item recipients
-Who to encrypt/sign the part to. This field is used to override any
-auto-detection based on the To/CC headers.
+@item time-less-p
+Take two times and say whether the first time is less (i. e., earlier)
+than the second time.
-@item size
-The size (in octets) of the part (@code{Content-Disposition}).
+@item time-since
+Take a time and return a time saying how long it was since that time.
-@item sign
-What technology to sign this MML part with (@code{smime}, @code{pgp}
-or @code{pgpmime})
+@item subtract-time
+Take two times and subtract the second from the first. I. e., return
+the time between the two times.
-@item encrypt
-What technology to encrypt this MML part with (@code{smime},
-@code{pgp} or @code{pgpmime})
+@item days-between
+Take two days and return the number of days between those two days.
-@end table
+@item date-leap-year-p
+Take a year number and say whether it's a leap year.
-Parameters for @samp{application/octet-stream}:
+@item time-to-day-in-year
+Take a time and return the day number within the year that the time is
+in.
-@table @samp
-@item type
-Type of the part; informal---meant for human readers
-(@code{Content-Type}).
@end table
-Parameters for @samp{message/external-body}:
-@table @samp
-@item access-type
-A word indicating the supported access mechanism by which the file may
-be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
-@samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
+@node qp
+@section qp
-@item expiration
-The RFC822 date after which the file may no longer be fetched.
-(@code{Content-Type}.)
+This library deals with decoding and encoding Quoted-Printable text.
-@item size
-The size (in octets) of the file. (@code{Content-Type}.)
+Very briefly explained, qp encoding means translating all 8-bit
+characters (and lots of control characters) into things that look like
+@samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
+string.
-@item permission
-Valid values are @samp{read} and @samp{read-write}
-(@code{Content-Type}).
+The following functions are defined by the library:
-@end table
+@table @code
+@item quoted-printable-decode-region
+@findex quoted-printable-decode-region
+QP-decode all the encoded text in the specified region.
-Parameters for @samp{sign=smime}:
+@item quoted-printable-decode-string
+@findex quoted-printable-decode-string
+Decode the QP-encoded text in a string and return the results.
-@table @samp
+@item quoted-printable-encode-region
+@findex quoted-printable-encode-region
+QP-encode all the encodable characters in the specified region. The third
+optional parameter @var{fold} specifies whether to fold long lines.
+(Long here means 72.)
-@item keyfile
-File containing key and certificate for signer.
+@item quoted-printable-encode-string
+@findex quoted-printable-encode-string
+QP-encode all the encodable characters in a string and return the
+results.
@end table
-Parameters for @samp{encrypt=smime}:
-
-@table @samp
-
-@item certfile
-File containing certificate for recipient.
-@end table
+@node base64
+@section base64
+@cindex base64
+Base64 is an encoding that encodes three bytes into four characters,
+thereby increasing the size by about 33%. The alphabet used for
+encoding is very resistant to mangling during transit.
-@node Advanced MML Example
-@section Advanced MML Example
+The following functions are defined by this library:
-Here's a complex multipart message. It's a @samp{multipart/mixed} that
-contains many parts, one of which is a @samp{multipart/alternative}.
+@table @code
+@item base64-encode-region
+@findex base64-encode-region
+base64 encode the selected region. Return the length of the encoded
+text. Optional third argument @var{no-line-break} means do not break
+long lines into shorter lines.
-@example
-<#multipart type=mixed>
-<#part type=image/jpeg filename=~/rms.jpg disposition=inline>
-<#multipart type=alternative>
-This is a plain text part.
-<#part type=text/enriched name=enriched.txt>
-<center>This is a centered enriched part</center>
-<#/multipart>
-This is a new plain text part.
-<#part disposition=attachment>
-This plain text part is an attachment.
-<#/multipart>
-@end example
+@item base64-encode-string
+@findex base64-encode-string
+base64 encode a string and return the result.
-And this is the resulting @sc{mime} message:
+@item base64-decode-region
+@findex base64-decode-region
+base64 decode the selected region. Return the length of the decoded
+text. If the region can't be decoded, return @code{nil} and don't
+modify the buffer.
-@example
-Content-Type: multipart/mixed; boundary="=-=-="
+@item base64-decode-string
+@findex base64-decode-string
+base64 decode a string and return the result. If the string can't be
+decoded, @code{nil} is returned.
+@end table
---=-=-=
+@node binhex
+@section binhex
+@cindex binhex
+@cindex Apple
+@cindex Macintosh
+@code{binhex} is an encoding that originated in Macintosh environments.
+The following function is supplied to deal with these:
---=-=-=
-Content-Type: image/jpeg;
- filename="~/rms.jpg"
-Content-Disposition: inline;
- filename="~/rms.jpg"
-Content-Transfer-Encoding: base64
+@table @code
+@item binhex-decode-region
+@findex binhex-decode-region
+Decode the encoded text in the region. If given a third parameter, only
+decode the @code{binhex} header and return the filename.
-/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
-Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
-AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
-BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
-RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
-qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
-AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
-AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
-sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
-2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
-5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
-L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
-34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
-tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
-7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
-pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
-jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
+@end table
---=-=-=
-Content-Type: multipart/alternative; boundary="==-=-="
+@node uudecode
+@section uudecode
+@cindex uuencode
+@cindex uudecode
---==-=-=
+@code{uuencode} is probably still the most popular encoding of binaries
+used on Usenet, although @code{base64} rules the mail world.
+The following function is supplied by this package:
-This is a plain text part.
+@table @code
+@item uudecode-decode-region
+@findex uudecode-decode-region
+Decode the text in the region.
+@end table
---==-=-=
-Content-Type: text/enriched;
- name="enriched.txt"
+@node rfc1843
+@section rfc1843
+@cindex rfc1843
+@cindex HZ
+@cindex Chinese
-<center>This is a centered enriched part</center>
+RFC1843 deals with mixing Chinese and ASCII characters in messages. In
+essence, RFC1843 switches between ASCII and Chinese by doing this:
---==-=-=--
+@example
+This sentence is in ASCII.
+The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
+@end example
---=-=-=
+Simple enough, and widely used in China.
-This is a new plain text part.
+The following functions are available to handle this encoding:
---=-=-=
-Content-Disposition: attachment
+@table @code
+@item rfc1843-decode-region
+Decode HZ-encoded text in the region.
+@item rfc1843-decode-string
+Decode a HZ-encoded string and return the result.
-This plain text part is an attachment.
+@end table
---=-=-=--
-@end example
-@node Charset Translation
-@section Charset Translation
-@cindex charsets
+@node mailcap
+@section mailcap
-During translation from MML to @sc{mime}, for each @sc{mime} part which
-has been composed inside Emacs, an appropriate charset has to be chosen.
+The @file{~/.mailcap} file is parsed by most @sc{mime}-aware message
+handlers and describes how elements are supposed to be displayed.
+Here's an example file:
-@vindex mail-parse-charset
-If you are running a non-@sc{mule} Emacs, this process is simple: If the
-part contains any non-ASCII (8-bit) characters, the @sc{mime} charset
-given by @code{mail-parse-charset} (a symbol) is used. (Never set this
-variable directly, though. If you want to change the default charset,
-please consult the documentation of the package which you use to process
-@sc{mime} messages.
-@xref{Various Message Variables, , Various Message Variables, message,
- Message Manual}, for example.)
-If there are only ASCII characters, the @sc{mime} charset US-ASCII is
-used, of course.
+@example
+image/*; gimp -8 %s
+audio/wav; wavplayer %s
+application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
+@end example
-@cindex MULE
-@cindex UTF-8
-@cindex Unicode
-@vindex mm-mime-mule-charset-alist
-Things are slightly more complicated when running Emacs with @sc{mule}
-support. In this case, a list of the @sc{mule} charsets used in the
-part is obtained, and the @sc{mule} charsets are translated to @sc{mime}
-charsets by consulting the variable @code{mm-mime-mule-charset-alist}.
-If this results in a single @sc{mime} charset, this is used to encode
-the part. But if the resulting list of @sc{mime} charsets contains more
-than one element, two things can happen: If it is possible to encode the
-part via UTF-8, this charset is used. (For this, Emacs must support
-the @code{utf-8} coding system, and the part must consist entirely of
-characters which have Unicode counterparts.) If UTF-8 is not available
-for some reason, the part is split into several ones, so that each one
-can be encoded with a single @sc{mime} charset. The part can only be
-split at line boundaries, though---if more than one @sc{mime} charset is
-required to encode a single line, it is not possible to encode the part.
+This says that all image files should be displayed with @code{gimp},
+that WAVE audio files should be played by @code{wavplayer}, and that
+MS-WORD files should be inlined by @code{catdoc}.
-@node Conversion
-@section Conversion
+The @code{mailcap} library parses this file, and provides functions for
+matching types.
-@findex mime-to-mml
-A (multipart) @sc{mime} message can be converted to MML with the
-@code{mime-to-mml} function. It works on the message in the current
-buffer, and substitutes MML markup for @sc{mime} boundaries.
-Non-textual parts do not have their contents in the buffer, but instead
-have the contents in separate buffers that are referred to from the MML
-tags.
+@table @code
+@item mailcap-mime-data
+@vindex mailcap-mime-data
+This variable is an alist of alists containing backup viewing rules.
-@findex mml-to-mime
-An MML message can be converted back to @sc{mime} by the
-@code{mml-to-mime} function.
+@end table
-These functions are in certain senses ``lossy''---you will not get back
-an identical message if you run @sc{mime-to-mml} and then
-@sc{mml-to-mime}. Not only will trivial things like the order of the
-headers differ, but the contents of the headers may also be different.
-For instance, the original message may use base64 encoding on text,
-while @sc{mml-to-mime} may decide to use quoted-printable encoding, and
-so on.
+Interface functions:
-In essence, however, these two functions should be the inverse of each
-other. The resulting contents of the message should remain equivalent,
-if not identical.
+@table @code
+@item mailcap-parse-mailcaps
+@findex mailcap-parse-mailcaps
+Parse the @code{~/.mailcap} file.
+@item mailcap-mime-info
+Takes a @sc{mime} type as its argument and returns the matching viewer.
-@node Flowed text
-@section Flowed text
-@cindex format=flowed
+@end table
-The Emacs @sc{mime} library will respect the @code{use-hard-newlines}
-variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
-emacs, Emacs Manual}) when encoding a message, and the
-``format=flowed'' Content-Type parameter when decoding a message.
-On encoding text, lines terminated by soft newline characters are
-filled together and wrapped after the column decided by
-@code{fill-flowed-encode-column}. This variable controls how the text
-will look in a client that does not support flowed text, the default
-is to wrap after 66 characters. If hard newline characters are not
-present in the buffer, no flow encoding occurs.
-On decoding flowed text, lines with soft newline characters are filled
-together and wrapped after the column decided by
-@code{fill-flowed-display-column}. The default is to wrap after
-@code{fill-column}.
@node Standards
@chapter Standards
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