\input texinfo-ja @c -*-texinfo -*- coding: utf-8 -*-
@c Generated automatically from mime-en.sgml by sinfo 3.7.
@setfilename mime-en.info
@settitle FLIM-LB 1.14 Reference Manual about MIME Features
@documentencoding utf-8
@documentlanguage en
@dircategory GNU Emacs Lisp
@direntry
* FLIM-LB (en): (mime-en).         Internet message library.
@end direntry
@titlepage
@title FLIM-LB 1.14 Reference Manual about MIME Features
@author MORIOKA Tomohiko <morioka@@jaist.ac.jp>
@author Kazuhiro Ito
@subtitle 2020-09-17
@end titlepage
@node Top, Introduction, (dir), (dir)
@top FLIM-LB 1.14 Reference Manual about MIME Features

@ifinfo

This file documents MIME features of FLIM-LB, a fundamental library to
process Internet Messages for GNU Emacsen.
@end ifinfo

@menu
* Introduction::                What is FLIM-LB?
* How to use::                  How to use MIME features
* Entity::                      Message and Entity
* Content-Type::                Information of Content-Type field
* Content-Disposition::         Information of Content-Disposition field
* Content-Transfer-Encoding::   Encoding Method
* encoded-word::                Network representation of header
* custom::                      Various Customization
* Appendix::
* Concept Index::
* Function Index::
* Variable Index::
@end menu

@node Introduction, How to use, Top, Top
@chapter What is FLIM-LB?

FLIM is a library to provide basic features about message
representation or encoding.  FLIM-LB is a variant of FLIM, which
features supports to latest Emacs.


@node How to use, Entity, Introduction, Top
@chapter How to use MIME features

Please eval following to use MIME features provided by FLIM:

@lisp
(require 'mime)
@end lisp



@node Entity, Content-Type, How to use, Top
@chapter Message and Entity
@cindex mime-entity
@cindex entity

According to RFC 2045 (@ref{RFC 2045}), `The term ``entity'', refers
specifically to the MIME-defined header fields and contents of either a
message or one of the parts in the body of a multipart entity.'  In this
document, the term @strong{entity} indicates all of header fields and
body.@refill

The definition of RFC 2045 indicates that a MIME message is a tree, and
each node of the tree is an entity.  Namely MIME extends message to tree
structure.@refill

FLIM uses @strong{mime-entity} structure to represent
information of entity.  In this document, it is called simply
`mime-entity'.


@menu
* Entity creation::             Functions to create mime-entity
* Entity hierarchy::            Features about message tree
* Entity Search::               Find Entity
* Entity Attributes::           Functions about attributes of mime-entity
* Entity-header::               Information of entity header
* entity formatting::           Text presentation of entity
* Entity-content::              Contents of Entity
* Entity-network-representation::  Network representation of Entity
* Entity buffer::               Entity as buffer representation
* mm-backend::                  Entity representations and implementations
@end menu

@node Entity creation, Entity hierarchy, Entity, Entity
@section Functions to create mime-entity

@defun mime-open-entity &optional  type location

Open an entity and return it.@refill

@var{type} is representation-type. (cf. @ref{mm-backend}) @refill

@var{location} is location of entity.  Specification of it is depended
on representation-type.
@end defun


@defun mime-parse-buffer &optional  buffer type

Parse @var{buffer} as message, and set the result to buffer local
variable @code{mime-message-structure} of @var{buffer} as
mime-entity.@refill

If @var{buffer} is omitted, current buffer is used.@refill

@var{type} is representation-type of created
mime-entity. (cf. @ref{mm-backend}) Default value is @var{buffer}.
@end defun



@node Entity hierarchy, Entity Search, Entity creation, Entity
@section Features about message tree
@cindex node-id
@cindex entity-number
@cindex message
@cindex root-entity

Structure of a MIME message is tree.@refill

In the tree, root node is the entity indicates all of the message.  In
this document, it is called @strong{root-entity} or @strong{message}.
In FLIM, it is indicated by buffer local variable
@code{mime-message-structure}.@refill

Each entity except root-entity has a parent.  An entity may have
children.  We can indicate an entity by relative position from a base
entity, based on the parent-child relationship.@refill

In addition, we can indicate an entity by absolute position of the
message.@refill

Each entity, which is a node of the tree, can be numbered by
depth and left-to-right order of the depth.
@example

                              +-------+
                              |  nil  |
                              +---+---+
              +-------------------+-------------------+
            +-+-+               +-+-+               +-+-+
            | 0 |               | 1 |               | 2 |
            +-+-+               +-+-+               +-+-+
              |         +---------+---------+         |
           +--+--+   +--+--+   +--+--+   +--+--+   +--+--+
           | 0.0 |   | 1.0 |   | 1.1 |   | 1.2 |   | 2.0 |
           +-----+   +-----+   +-----+   +-----+   +-----+
@end example

Namely, if depth of a node is n, the node has a node-number, which is
consists of n integers.  In this document, it is called
@strong{entity-number}.  An entity-number is represented by list of
integer, like @code{(1 2 3)}.@refill

mime-entity has also @strong{node-id}.  A node-id is represented by
reversed list of entity-number.  For example, node-id corresponding with
1.2.3 is @code{(3 2 1)}.@refill

Each entity can be indicated by entity-number or node-id in
@code{mime-message-structure}.

@defvar mime-message-structure

Buffer local variable to store mime-entity structure of message.
@end defvar


@defun mime-entity-children entity

Return list of entities included in the @var{entity}.
@end defun


@defun mime-entity-parent entity  &optional  message

Return parent entity of the @var{entity}.@refill

If @var{message} is specified, it is regarded as root instead of
@code{mime-message-structure}.
@end defun


@defun mime-root-entity-p entity

Return non-@code{nil} if @var{entity} is root entity (message).
@end defun


@defun mime-entity-node-id entity

Return node-id of @var{entity}.
@end defun


@defun mime-entity-number entity

Return entity-number of @var{entity}.
@end defun



@node Entity Search, Entity Attributes, Entity hierarchy, Entity
@section Find Entity

@defun mime-find-entity-from-number entity-number  &optional  message

Return entity from @var{entity-number} in @var{message}.@refill

If @var{message} is not specified, @code{mime-message-structure} is
used.
@end defun


@defun mime-find-entity-from-node-id entity-node-id  &optional  message

Return entity from @var{entity-node-id} in @var{message}.@refill

If @var{message} is not specified, @code{mime-message-structure} is
used.
@end defun


@defun mime-find-entity-from-content-id cid  &optional  message

Return entity from @var{cid} in @var{message}.@refill

If @var{message} is not specified, @code{mime-message-structure} is
used.
@end defun



@node Entity Attributes, Entity-header, Entity Search, Entity
@section Functions about attributes of mime-entity

@defun mime-entity-content-type entity

Return content-type of @var{entity}.  (cf. @ref{mime-content-type})
@end defun


@defun mime-entity-content-disposition entity

Return content-disposition of
@var{entity}. (cf. @ref{mime-content-disposition})
@end defun


@defun mime-entity-filename entity

Return file name of @var{entity}.
@end defun


@defun mime-entity-encoding entity  &optional  default-encoding

Return content-transfer-encoding of @var{entity}.
(cf. @ref{Content-Transfer-Encoding}) @refill

If the @var{entity} does not have Content-Transfer-Encoding field, this
function returns @var{default-encoding}.  If it is nil, @code{"7bit"} is
used as default value.
@end defun


@defun mime-entity-cooked-p entity

Return non-nil if contents of @var{entity} has been already
code-converted.
@end defun



@node Entity-header, entity formatting, Entity Attributes, Entity
@section Information of entity header

@defun mime-fetch-field field-name  &optional  entity

Return field-body of @var{field-name} field in header of
@var{entity}.@refill

The results is network representation.@refill

If @var{entity} is omitted, @code{mime-message-structure} is used as
default value.@refill

If @var{field-name} field is not found, this function returns
@code{nil}.
@end defun


@defun mime-read-field field-name  &optional  entity

Parse @var{field-name} field in header of @var{entity}, and return the
result.@refill

Format of result is depended on kind of field.  For non-structured
field, this function returns string.  For structured field, it returns
list corresponding with structure of the field.@refill

Strings in the result will be converted to internal representation of
Emacs.@refill

If @var{entity} is omitted, @code{mime-message-structure} is used as
default value.@refill

If @var{field-name} field is not found, this function returns
@code{nil}.
@end defun



@node entity formatting, Entity-content, Entity-header, Entity
@section Text presentation of entity

@defun mime-insert-header entity  &optional  invisible-fields visible-fields

Insert before point a decoded contents of header of @var{entity}.@refill

@var{invisible-fields} is list of regexps to match field-name to hide.
@var{visible-fields} is list of regexps to match field-name to
hide.@refill

If a field-name is matched with some elements of @var{invisible-fields}
and matched with none of @var{visible-fields}, this function don't
insert the field.@refill

Each encoded-word (@ref{encoded-word}) in the header is decoded.  ``Raw
non us-ascii characters'' are also decoded as
@code{default-mime-charset}.
@end defun


@defun mime-insert-text-content entity

Insert before point a contents of @var{entity} as text entity.@refill

Contents of the @var{entity} are decoded as MIME charset (@ref{MIME charset}).  If the @var{entity} does not have charset parameter of
Content-Type field, @code{default-mime-charset} is used as default
value.
@end defun


@defvar default-mime-charset

Symbol to indicate default value of MIME charset (@ref{MIME charset}).@refill

It is used when MIME charset is not specified.@refill

It is originally variable of APEL.
@end defvar



@node Entity-content, Entity-network-representation, entity formatting, Entity
@section Contents of Entity

@defun mime-entity-content entity

Return content of @var{entity} as byte sequence.
@end defun


@defun mime-insert-entity-content entity

Insert content of @var{entity} at point.
@end defun


@defun mime-write-entity-content entity filename

Write content of @var{entity} into @var{filename}.
@end defun



@node Entity-network-representation, Entity buffer, Entity-content, Entity
@section Network representation of Entity

@defun mime-insert-entity entity

Insert header and body of @var{entity} at point.
@end defun


@defun mime-write-entity entity filename

Write representation of @var{entity} into @var{filename}.
@end defun


@defun mime-write-entity-body entity filename

Write body of @var{entity} into @var{filename}.
@end defun



@node Entity buffer, mm-backend, Entity-network-representation, Entity
@section Entity as buffer representation

@defun mime-entity-buffer entity

Return buffer, which contains @var{entity}.
@end defun


@defun mime-entity-point-min entity

Return the start point of @var{entity} in the buffer which contains
@var{entity}.
@end defun


@defun mime-entity-point-max entity

Return the end point of @var{entity} in the buffer which contains
@var{entity}.
@end defun


@defun mime-entity-header-start entity

Return the start point of header of @var{entity} in the buffer which
contains @var{entity}.
@end defun


@defun mime-entity-header-end entity

Return the end point of header of @var{entity} in the buffer which
contains @var{entity}.
@end defun


@defun mime-entity-body-start entity

Return the start point of body of @var{entity} in the buffer which
contains @var{entity}.
@end defun


@defun mime-entity-body-end entity

Return the end point of body of @var{entity} in the buffer which
contains @var{entity}.
@end defun



@node mm-backend,  , Entity buffer, Entity
@section Entity representations and implementations
@cindex mm-backend
@cindex entity processing method
@cindex representation-type

Entity is an abstraction.  It is designed to use various data
representations for their purposes.@refill

Each entity has @strong{representation-type}.  It must be specified when
an entity is created. (cf. @ref{Entity creation}) @refill

Functions about entity are implemented by request processing to the
entity.  Each entity knows its representation-type.  Each entity calls
processing function corresponding with the representation-type.  Such
kind of function is called @strong{entity processing method}.  A module,
consists of them corresponding with a representation-type, is called
@strong{mm-backend}.@refill

Module name of each mm-backend consists of the prefix @code{mm}
and its representation-type.  The module is required automatically
when its entity is created at first.


@menu
* Request for entity::          Message-passing for entity
* mm-backend module::           Definition of mm-backend
@end menu

@node Request for entity, mm-backend module, mm-backend, mm-backend
@subsection Message-passing for entity

@defun mime-entity-send entity message  &rest  args

Send @var{message} to @var{entity} with @var{args}, and return the
result.@refill

@var{args} is arguments of the @var{message}.
@end defun



@node mm-backend module,  , Request for entity, mm-backend
@subsection Definition of mm-backend

@defmac mm-define-backend type &optional  parents

Define @var{type} as a mm-backend.@refill

If @var{PARENTS} is specified, @var{type} inherits parents.  Each parent
must be representation-type.@refill

Example:@refill

@lisp
(mm-define-backend chao (generic))
@end lisp
@end defmac


@defmac mm-define-method name args  &rest  body

Define @var{name} as a method function of (nth 1 (car @var{args}))
backend.@refill

@var{args} is like an argument list of lambda, but (car @var{args}) must
be specialized parameter.  (car (car @var{args})) is name of variable
and (nth 1 (car @var{args})) is name of backend
(representation-type).@refill

Example:@refill

@lisp
(mm-define-method entity-cooked-p ((entity chao)) nil)
@end lisp
@end defmac



@node Content-Type, Content-Disposition, Entity, Top
@chapter Information of Content-Type field
@cindex mime-content-type
@cindex Content-Type field

@strong{Content-Type field} is a field to indicate kind of contents or
data format, such as media-type (@ref{media-type}) and MIME charset.  It
is defined in RFC 2045 (@ref{RFC 2045}).

@noindent
@strong{[Memo]}
@quotation

Historically, Content-Type field was proposed in RFC 1049.  In it,
Content-Type did not distinguish type and subtype, and there are no
mechanism to represent kind of character code like MIME charset.
@end quotation


FLIM provides parser for Content-Type field and structure
@strong{mime-content-type} to store information of
Content-Type field.


@menu
* Content-Type field::          Format of Content-Type field
* mime-content-type::           mime-content-type structure
* Content-Type parser::         Parser
* Content-Type utility::        Utility functions
@end menu

@node Content-Type field, mime-content-type, Content-Type, Content-Type
@section Format of Content-Type field
@cindex parameter
@cindex subtype
@cindex type

Format of Content-Type field is defined as follows:

@quotation
``Content-Type'' ``:'' @strong{type} ``/''
@strong{subtype} *( ``;'' @strong{parameter} )
@end quotation

For example:

@quotation
@example
Content-Type: image/jpeg
@end example
@end quotation


@quotation
@example
Content-Type: text/plain; charset=iso-2022-jp
@end example
@end quotation

`type' and `subtype' indicate format of an entity.  In this document,
pair of them is called `media-type'.  `image/jpeg' or `text/plain' is
a media-type.

@noindent
@strong{[Memo]}
@quotation

If an entity does not have Content-Type field, it is regarded as
following:

@quotation
@example
Content-Type: text/plain; charset=us-ascii
@end example
@end quotation

@noindent
(cf. @ref{us-ascii})
@end quotation



@node mime-content-type, Content-Type parser, Content-Type field, Content-Type
@section mime-content-type structure

@deffn{Structure} mime-content-type

Structure to store information of a Content-Type field.@refill

Applications should use reference functions
@code{mime-content-type-SLOT} to refer information of the
structure.@refill

Slots of the structure are following:

@table @var
@item primary-type
primary type of media-type (symbol).

@item subtype
subtype of media-type (symbol).

@item parameters
parameters of Content-Type field (association-list).

@end table
@end deffn


@defun make-mime-content-type type subtype
	   &optional  parameters

Constructor of content-type.
@end defun


@defun mime-content-type-parameter content-type parameter

Return value of @var{parameter} of @var{content-type}.
@end defun



@node Content-Type parser, Content-Type utility, mime-content-type, Content-Type
@section Parser

@defun mime-parse-Content-Type string

Parse @var{string} as a field-body of Content-Type field, and return the
result as mime-content-type (@ref{mime-content-type}) structure.
@end defun


@defun mime-read-Content-Type

Parse Content-Type field of the current buffer, and return the result as
mime-content-type (@ref{mime-content-type}) structure.@refill

Return @code{nil} if Content-Type field is not found.
@end defun



@node Content-Type utility,  , Content-Type parser, Content-Type
@section Utility functions

@defun mime-type/subtype-string type  &optional  subtype

Return type/subtype string from @var{type} and @var{subtype}.
@end defun



@node Content-Disposition, Content-Transfer-Encoding, Content-Type, Top
@chapter Information of Content-Disposition field
@cindex mime-content-disposition
@cindex RFC 2183
@cindex Standards Track
@cindex Content-Disposition field

@strong{Content-Disposition field} is an optional field to
specify presentation of an entity or attributes of an entity, such as
file name.


@noindent
[RFC 2183]
@quotation
S. Dorner, K. Moore and R. Troost, ``Communicating Presentation
Information in Internet Messages: The Content-Disposition Header'',
August 1997, Standards Track.
@end quotation

FLIM provides parser for Content-Disposition field and structure
@strong{mime-content-disposition} to store information of
Content-Disposition field.


@menu
* mime-content-disposition::    mime-content-disposition structure
* Content-Disposition parser::  Parser for Content-Disposition field
@end menu

@node mime-content-disposition, Content-Disposition parser, Content-Disposition, Content-Disposition
@section mime-content-disposition structure

@deffn{Structure} mime-content-disposition

Structure to store information of a Content-Disposition field.@refill

Applications should use reference functions
@code{mime-content-disposition-SLOT} to refer information of the
structure.@refill

Slots of the structure are following:

@table @var
@item disposition-type
disposition-type (symbol).

@item parameters
parameters of Content-Disposition field
(association-list).

@end table
@end deffn


@defun mime-content-disposition-parameter content-disposition parameter

Return value of @var{parameter} of @var{content-disposition}.
@end defun


@defun mime-content-disposition-filename content-disposition

Return filename of @var{content-disposition}.
@end defun



@node Content-Disposition parser,  , mime-content-disposition, Content-Disposition
@section Parser for Content-Disposition field

@defun mime-parse-Content-Disposition string

Parse @var{string} as field-body of Content-Disposition field, and
return the result as mime-content-disposition
(@ref{mime-content-disposition}) structure.
@end defun


@defun mime-read-Content-Disposition

Parse Content-Disposition field of the current buffer, and return the
result as mime-content-disposition (@ref{mime-content-disposition})
structure.@refill

Return @code{nil} if Content-Disposition field is not found.
@end defun



@node Content-Transfer-Encoding, encoded-word, Content-Disposition, Top
@chapter Encoding Method
@cindex Content-Transfer-Encoding field

@strong{Content-Transfer-Encoding field} is a header field to indicate
body encoding of a entity.@refill

FLIM provides parser functions for Content-Transfer-Encoding field.
They represent information of Content-Transfer-Encoding field as
string.@refill

In addition, FLIM provides encoder/decoder functions by
Content-Transfer-Encoding.


@menu
* Content-Transfer-Encoding parser::  Parser
* encoder/decoder::             Encoder/decoder
* Encoding information::        Other utilities
* mel-backend::                 How to write encoder/decoder module
* generic function for mel-backend::  How to add encoding/decoding service
@end menu

@node Content-Transfer-Encoding parser, encoder/decoder, Content-Transfer-Encoding, Content-Transfer-Encoding
@section Parser

@defun mime-parse-Content-Transfer-Encoding string

Parse @var{string} as a field-body of Content-Transfer-Encoding field,
and return the result.
@end defun


@defun mime-read-Content-Transfer-Encoding &optional default-encoding

Parse Content-Transfer-Encoding field of the current buffer, and return
the result.@refill

Return @var{default-encoding} if Content-Transfer-Encoding field is not
found.  If it is not specified, @code{nil} is used as the default value.
@end defun



@node encoder/decoder, Encoding information, Content-Transfer-Encoding parser, Content-Transfer-Encoding
@section Encoder/decoder

@defun mime-encode-region start end encoding

Encode region @var{start} to @var{end} of current buffer using
@var{encoding}.
@end defun


@defun mime-decode-region start end encoding

Decode region @var{start} to @var{end} of current buffer using
@var{encoding}.
@end defun



@defun mime-decode-string string encoding

Decode @var{string} which is encoded in @var{encoding}, and return the
result.
@end defun



@defun mime-insert-encoded-file filename encoding

Insert file @var{FILENAME} encoded by @var{ENCODING} format.
@end defun


@defun mime-write-decoded-region start end filename encoding

Decode and write current region encoded by @var{encoding} into
@var{filename}.@refill

@var{start} and @var{end} are buffer positions.
@end defun



@node Encoding information, mel-backend, encoder/decoder, Content-Transfer-Encoding
@section Other utilities

@defun mime-encoding-list &optional  SERVICE

Return list of Content-Transfer-Encoding.@refill

If @var{service} is specified, it returns available list of
Content-Transfer-Encoding for it.
@end defun


@defun mime-encoding-alist &optional  SERVICE

Return table of Content-Transfer-Encoding for completion.@refill

If @var{service} is specified, it returns available list of
Content-Transfer-Encoding for it.
@end defun



@node mel-backend, generic function for mel-backend, Encoding information, Content-Transfer-Encoding
@section How to write encoder/decoder module

@defmac mel-define-method name args  &rest  body

Define @var{name} as a method function of (nth 1 (car (last
@var{args}))) backend.@refill

@var{args} is like an argument list of lambda, but (car (last
@var{args})) must be specialized parameter.  (car (car (last
@var{args}))) is name of variable and (nth 1 (car (last @var{args}))) is
name of backend (encoding).@refill

Example:@refill

@lisp
(mel-define-method mime-write-decoded-region (start end filename
						    (nil "base64"))
  "Decode and write current region encoded by base64 into FILENAME.
START and END are buffer positions."
  (interactive
   (list (region-beginning) (region-end)
	 (read-file-name "Write decoded region to file: ")))
  (let ((str (buffer-substring start end)))
    (with-temp-buffer
      (insert (decode-base64-string str))
      (write-region-as-binary (point-min) (point-max) filename)
      )))
@end lisp
@end defmac


@defmac mel-define-method-function spec function

Set @var{spec}'s function definition to @var{function}.@refill

First element of @var{spec} is service.@refill

Rest of @var{args} is like an argument list of lambda, but (car (last
@var{args})) must be specialized parameter.  (car (car (last
@var{args}))) is name of variable and (nth 1 (car (last @var{args}))) is
name of backend (encoding).@refill

Example:@refill

@lisp
(mel-define-method-function (mime-encode-string string (nil "base64"))
			    'encode-base64-string)
@end lisp
@end defmac



@node generic function for mel-backend,  , mel-backend, Content-Transfer-Encoding
@section How to add encoding/decoding service

@defmac mel-define-service name &optional  args doc-string

Define @var{name} as a service for Content-Transfer-Encodings.@refill

If @var{args} is specified, @var{name} is defined as a generic function
for the service.@refill

Example:@refill

@lisp
(mel-define-service encoded-text-encode-string (string encoding)
  "Encode STRING as encoded-text using ENCODING.
ENCODING must be string.")
@end lisp
@end defmac



@node encoded-word, custom, Content-Transfer-Encoding, Top
@chapter Network representation of header
@cindex RFC 2047
@cindex Standards Track
@cindex encoded-word
@cindex RFC 2047

@strong{RFC 2047} defines the @strong{encoded-word} which is a format to
represent non-ASCII (@ref{ASCII}) characters in a header.@refill


@noindent
[RFC 2047]
@quotation
K. Moore, ``MIME (Multipurpose Internet Mail Extensions) Part Three:
Message Header Extensions for Non-ASCII Text'', November 1996, Standards
Track (obsolete RFC 1521,1522,1590).
@end quotation

The encoded-word is the only valid format to represent non-ASCII
(@ref{ASCII}) characters in a header, but there are also invalid styles.
Such kinds of evil messages represent non-ASCII (@ref{ASCII}) characters
in headers without encoded-words (it is called "raw" non-ASCII
(@ref{ASCII}) characters).@refill

FLIM provides encoding/decoding features of both encoded-word and
invalid "raw" non-ASCII (@ref{ASCII}) characters.


@menu
* Header encoder/decoder::      Header encoding/decoding
@end menu

@node Header encoder/decoder,  , encoded-word, encoded-word
@section Header encoding/decoding

@defun eword-decode-header &optional  code-conversion separator

Decode MIME encoded-words in header fields.@refill

If @var{code-conversion} is @code{nil}, only encoded-words are decoded.
If @var{code-conversion} is a MIME charset (@ref{MIME charset}),
non-ASCII bit patterns are decoded as the MIME charset.  Otherwise
non-ASCII bit patterns are decoded as the
@code{default-mime-charset}. (cf. @ref{entity formatting}) @refill

If @var{separator} is not @code{nil}, it is used as header separator.
@end defun


@defun eword-encode-header &optional  code-conversion

Encode header fields to network representation, such as MIME
encoded-word.@refill

Each field is encoded as corresponding method specified by variable
@code{mime-field-encoding-method-alist}.
@end defun


@defvar mime-field-encoding-method-alist

Association list to specify field encoding method.  Each element looks
like (FIELD . METHOD).@refill

If METHOD is @code{mime}, the FIELD will be encoded into MIME format
(encoded-word).@refill

If METHOD is @code{nil}, the FIELD will not be encoded.@refill

If METHOD is a MIME charset, the FIELD will be encoded as the charset
when it must be convert into network-code.@refill

Otherwise the FIELD will be encoded as variable
@code{default-mime-charset} when it must be convert into network-code.
@end defvar



@node custom, Appendix, encoded-word, Top
@chapter Various Customization

@deffn{group} mime

The group associated with functions related to MIME.@refill

It belongs to @code{mail} and @code{news}.
@end deffn


@node Appendix, Concept Index, custom, Top
@chapter Appendix


@menu
* Glossary::                    
* Bug report::                  How to report bugs
* GitHub::                      GitHub based development
* History::                     History of FLIM
@end menu

@node Glossary, Bug report, Appendix, Appendix
@section Glossary


@menu
* 7bit::                        
* 8bit::                        
* ASCII::                       
* Base64::                      
* binary::                      
* coded character set::         Coded character set, Character code
* media-type::                  
* message::                     
* MIME::                        
* MIME charset::                
* MTA::                         
* MUA::                         
* Quoted-Printable::            
* RFC 822::                     
* RFC 1036::                    
* RFC 2045::                    
* RFC 2046::                    
* RFC 2048::                    
* RFC 2049::                    
* plain text::                  
* us-ascii::                    
@end menu

@node 7bit, 8bit, Glossary, Glossary
@subsection 7bit
@cindex 7bit (textual) string
@cindex 7bit data
@cindex 7bit

@strong{7bit} means any integer between 0 .. 127.@refill

Any data represented by 7bit integers is called @strong{7bit data}.@refill

Textual string consisted of Control characters between 0 .. 31 and 127,
and space represented by 32, and graphic characters between 33 .. 236
are called @strong{7bit (textual) string}.@refill

Conventional Internet MTA (@ref{MTA}) can translate 7bit data, so it is
no need to translate by Quoted-Printable (@ref{Quoted-Printable}) or
Base64 (@ref{Base64}) for 7bit data.@refill

However if there are too long lines, it can not translate by 7bit MTA
even if it is 7bit data.  RFC 822 (@ref{RFC 822}) and RFC 2045 (@ref{RFC 2045}) require lines in 7bit data must be less than 998 bytes.  So if a
``7bit data'' has a line more than 999 bytes, it is regarded as binary
(@ref{binary}).  For example, Postscript file should be encoded by
Quoted-Printable.


@node 8bit, ASCII, 7bit, Glossary
@subsection 8bit
@cindex 8bit (textual) string
@cindex 8bit data
@cindex 8bit

@strong{8bit} means any integer between 0 .. 255.@refill

Any data represented by 8bit integers is called @strong{8bit data}.@refill

Textual string consisted of Control characters between 0 .. 31, 127, and
128 .. 159, and space represented by 32, and graphic characters between
33 .. 236 and 160 .. 255 are called @strong{8bit (textual) string}.@refill

For example, iso-8859-1 or euc-kr are
coded-character-set represented by 8bit textual string.@refill

Traditional Internet MTA (@ref{MTA}) can translate only 7bit
(@ref{7bit}) data, so if a 8bit data will be translated such MTA, it
must be encoded by Quoted-Printable (@ref{Quoted-Printable}) or Base64
(@ref{Base64}).@refill

However 8bit MTA are increasing today.@refill

However if there are too long lines, it can not translate by 8bit MTA
even if it is 8bit data.  RFC 2045 (@ref{RFC 2045}) require lines in
8bit data must be less than 998 bytes.  So if a ``8bit data'' has a line
more than 999 bytes, it is regarded as binary (@ref{binary}), so it must
be encoded by Base64 or Quoted-Printable.


@node ASCII, Base64, 8bit, Glossary
@subsection ASCII
@cindex ANSI X3.4:1986
@cindex ASCII
@cindex ASCII

@strong{ASCII} is a 94-character set contains primary latin characters
(A-Z, a-z), numbers and some characters.  It is a standard of the United
States of America.  It is a variant of ISO 646.


@noindent
[ASCII]
@quotation
``Coded Character Set -- 7-Bit American Standard Code for Information
Interchange'', ANSI X3.4:1986.
@end quotation



@node Base64, binary, ASCII, Glossary
@subsection Base64
@cindex pad
@cindex Base64

@strong{Base64} is a transfer encoding method of MIME (@ref{MIME})
defined in RFC 2045 (@ref{RFC 2045}).@refill

The encoding process represents 24-bit groups of input bits as output
strings of 4 encoded characters.  Encoded characters represent integer 0
.. 63 or @strong{pad}.  Base64 data must be 4 * n bytes, so pad is used
to adjust size.@refill

These 65 characters are subset of all versions of ISO 646, including
US-ASCII, and all versions of EBCDIC.  So it is safe even if it is
translated by non-Internet gateways.


@node binary, coded character set, Base64, Glossary
@subsection binary
@cindex binary

Any byte stream is called @strong{binary}.@refill

It does not require structureof lines.  It differs from from 8bit
(@ref{8bit}).@refill

In addition, if line structured data contain too long line (more than
998 bytes), it is regarded as binary.


@node coded character set, media-type, binary, Glossary
@subsection Coded character set, Character code

A set of unambiguous rules that establishes a character set and the
one-to-one relationship between the characters of the set and their
bit combinations.


@node media-type, message, coded character set, Glossary
@subsection media-type
@cindex x-token
@cindex message
@cindex multipart
@cindex application
@cindex video
@cindex audio
@cindex image
@cindex text
@cindex subtype
@cindex type
@cindex media-type

@strong{media-type} specifies the nature of the data in the body of MIME
(@ref{MIME}) entity (@ref{Entity}).  It consists of @strong{type} and
@strong{subtype}.  It is defined in RFC 2046 (@ref{RFC 2046}).@refill

Currently there are following standard primary-types:

@itemize @bullet
@item
@strong{text}
@item
@strong{image}
@item
@strong{audio}
@item
@strong{video}
@item
@strong{application}
@item
@strong{multipart}
@item
@strong{message}
@end itemize


And there are various subtypes, for example, application/octet-stream,
audio/basic, image/jpeg, multipart/mixed,
text/plain, video/mpeg...  @refill

You can refer registered media types at MEDIA TYPES
(ftp://ftp.isi.edu/in-notes/iana/assignments/media-types).@refill

In addition, you can use private type or subtype using @strong{x-token},
which as the prefix `x-'.  However you can not use them in
public.@refill

(cf. @ref{Content-Type field})



@node message, MIME, media-type, Glossary
@subsection message

In this document, it means mail defined in RFC 822 (@ref{RFC 822}) and
news message defined in RFC 1036 (@ref{RFC 1036}).


@node MIME, MIME charset, message, Glossary
@subsection MIME
@cindex Multipurpose Internet Mail Extensions

MIME stands for @strong{Multipurpose Internet Mail Extensions}, it is an
extension for RFC 822 (@ref{RFC 822}).@refill

According to RFC 2045:@refill

STD 11, RFC 822, defines a message representation protocol specifying
considerable detail about US-ASCII message headers, and leaves the
message content, or message body, as flat US-ASCII text.  This set of
documents, collectively called the Multipurpose Internet Mail
Extensions, or MIME, redefines the format of messages to allow for

@enumerate
@item
textual message bodies in character sets other than US-ASCII,
@item
an extensible set of different formats for non-textual message
bodies,
@item
multi-part message bodies, and
@item
textual header information in character sets other than US-ASCII.
@end enumerate


It is defined in RFC 2045 (@ref{RFC 2045}), RFC 2046 (@ref{RFC 2046}),
RFC 2047 (@ref{encoded-word}), RFC 2048 (@ref{RFC 2048}) and RFC 2049
(@ref{RFC 2049}).


@node MIME charset, MTA, MIME, Glossary
@subsection MIME charset

Coded character set (@ref{coded character set}) used in Content-Type
field (@ref{Content-Type field}) or charset parameter of encoded-word
(@ref{encoded-word}).@refill

It is defined in RFC 2045 (@ref{RFC 2045}).@refill

iso-2022-jp or euc-kr are kinds of
it.  (In this document, MIME charsets are written by small letters to
distinguish graphic character set.  For
example, ISO 8859-1 is a graphic character set, and iso-8859-1 is a MIME
charset)


@node MTA, MUA, MIME charset, Glossary
@subsection MTA
@cindex Message Transfer Agent

@strong{Message Transfer Agent}.  It means mail transfer programs
(ex. sendmail) and news servers.@refill

(cf. @ref{MUA})



@node MUA, Quoted-Printable, MTA, Glossary
@subsection MUA
@cindex Message User Agent

@strong{Message User Agent}.  It means mail readers and news
readers.@refill

(cf. @ref{MTA})



@node Quoted-Printable, RFC 822, MUA, Glossary
@subsection Quoted-Printable
@cindex Quoted-Printable

@strong{Quoted-Printable} is a transfer encoding method of MIME
(@ref{MIME}) defined in RFC 2045 (@ref{RFC 2045}).@refill

If the data being encoded are mostly US-ASCII text, the encoded form of
the data remains largely recognizable by humans.@refill

(cf. @ref{Base64})



@node RFC 822, RFC 1036, Quoted-Printable, Glossary
@subsection RFC 822
@cindex RFC 822
@cindex STD 11
@cindex Internet mail
@cindex Internet message
@cindex message header

A RFC defines format of Internet mail message, mainly @strong{message header}.

@noindent
@strong{[Memo]}
@quotation

news message is based on RFC 822, so @strong{Internet message} may be
more suitable than @strong{Internet mail} .
@end quotation



@noindent
[RFC 822]
@quotation
D. Crocker, ``Standard for the Format of ARPA Internet Text Messages'',
August 1982, STD 11.
@end quotation



@node RFC 1036, RFC 2045, RFC 822, Glossary
@subsection RFC 1036
@cindex RFC 1036
@cindex USENET

A RFC defines format of USENET message.  It is a subset of RFC 822
(@ref{RFC 822}).  It is not Internet standard, but a lot of netnews
excepting Usenet uses it.


@noindent
[USENET: RFC 1036]
@quotation
M. Horton and R. Adams, ``Standard for Interchange of USENET Messages'',
December 1987, (obsolete RFC 850).
@end quotation



@node RFC 2045, RFC 2046, RFC 1036, Glossary
@subsection RFC 2045
@cindex RFC 2045
@cindex Standards Track


@noindent
[RFC 2045]
@quotation
N. Freed and N. Borenstein, ``Multipurpose Internet Mail Extensions
(MIME) Part One: Format of Internet Message Bodies'', November 1996,
Standards Track (obsolete RFC 1521, 1522, 1590).
@end quotation



@node RFC 2046, RFC 2048, RFC 2045, Glossary
@subsection RFC 2046
@cindex RFC 2046
@cindex Standards Track


@noindent
[RFC 2046]
@quotation
N. Freed and N. Borenstein, ``Multipurpose Internet Mail Extensions
(MIME) Part Two: Media Types'', November 1996, Standards Track (obsolete
RFC 1521, 1522, 1590).
@end quotation



@node RFC 2048, RFC 2049, RFC 2046, Glossary
@subsection RFC 2048
@cindex RFC 2048
@cindex Standards Track


@noindent
[RFC 2048]
@quotation
N. Freed, J. Klensin and J. Postel, ``Multipurpose Internet Mail
Extensions (MIME) Part Four: Registration Procedures'', November 1996,
Standards Track (obsolete RFC 1521, 1522, 1590).
@end quotation



@node RFC 2049, plain text, RFC 2048, Glossary
@subsection RFC 2049
@cindex RFC 2049
@cindex Standards Track


@noindent
[RFC 2049]
@quotation
N. Freed and N. Borenstein, ``Multipurpose Internet Mail Extensions
(MIME) Part Five: Conformance Criteria and Examples'', November 1996,
Standards Track (obsolete RFC 1521, 1522, 1590).
@end quotation



@node plain text, us-ascii, RFC 2049, Glossary
@subsection plain text

A textual data represented by only coded character set (@ref{coded character set}).  It does not have information about font or
typesetting.



@node us-ascii,  , plain text, Glossary
@subsection us-ascii
@cindex ASCII
@cindex us-ascii

A MIME charset (@ref{MIME charset}) for primary Latin script mainly
written by English or other languages.@refill

It is a 7bit coded character set (@ref{coded character set}) based on
ISO 2022, it contains only ASCII (@ref{ASCII}) and code
extension is not allowed.@refill

It is standard coded character set of Internet mail.  If MIME charset is
not specified, @strong{us-ascii} is used as default.@refill

In addition, @strong{ASCII} of RFC 822 (@ref{RFC 822}) should be
interpreted as us-ascii.


@node Bug report, GitHub, Glossary, Appendix
@section How to report bugs
@cindex good bug report

Topics related to FLIM-LB are discussed in following mailing lists.
The latest version is also announced there.

@display
Wanderlust Mailing List @t{<wl@@ml.gentei.org>}
@end display

In this list Japanese is mainly used for discussion. We also have a list
for discussion in English:

@display
Wanderlust List in English @t{<wl-en@@ml.gentei.org>}
@end display
(Messages posted to this list are also forwarded to the former one.)

A guide can be obtained automatically by sending mail to
@t{wl-ctl@@ml.gentei.org} (or to @t{wl-en-ctl@@ml.gentei.org} for
the English one) with the body

@example
# guide
@end example

Please send bug reports or patches to one of those lists.  You have to
subscribe the mailing list to post a message.

Notice that, we do not welcome bug reports about too old version.  Bugs
in old version might be fixed.  So please try latest version at
first.@refill

You should write @strong{good bug report}.  If you write only ``FLIM
does not work'', we can not find such situations.  At least, you
should write name, type, variants and version of OS, emacs, APEL,
FLIM, SEMI and MUA, and setting.  In addition, if error occurs, to
send backtrace is very important. (cf. @ref{Bugs,Reporting Bugs
,Reporting Bugs, emacs, GNU Emacs Manual}) @refill

Bug may not appear only your environment, but also in a lot of
environment (otherwise it might not bug).  Therefor if you send mail
to author directly, we must write a lot of mails.  So please send mail
to address for EMACS-MIME Mailing List instead of author.


@node GitHub, History, Bug report, Appendix
@section GitHub based development

FLIM-LB's repository is published in GitHub.

@example
@uref{https://github.com/wanderlust/flim}
@end example

If you send a pull request, please embed unindented @file{ChangeLog}
entries in commit message like Emacs's.  See @cite{Commit messages}
section of Emacs's CONTRIBUTE file
@footnote{@uref{https://git.savannah.gnu.org/cgit/emacs.git/plain/CONTRIBUTE}}.

If you send a bug report, please attach Backtrace with it.
@footnote{@uref{http://www.jpl.org/elips/BUGS-ja.html} describes how to
in Japanese.}


@node History,  , GitHub, Appendix
@section History of FLIM

FLIM の code の最古の部分は 榎並 嗣智 氏が書いた @file{mime.el} に起源し
ます。この小さな program は Nemacs で動作する iso-2022-jp の B-encoding 
専用の encoded-word の復号化プログラムでした。@refill

その後、守岡 知彦 は @file{mime.el} を元に@file{tiny-mime.el} というプロ
グラムを書きます。これは、Nemacs と Mule で動作する encoded-word の符号
化・復号化プログラムでした。@file{tiny-mime.el} は B-encoding だけでなく 
Q-encoding もsupport し、また、MULE で扱うことができるさまざまな MIME
charset (@ref{MIME charset}) を同時に使うことができました。この時、
Nemacs と Mule の双方を support するために用いられたテクニックは後に emu
package にまとめられます。@refill

この頃、守岡 知彦 は @file{tiny-mime.el} をさまざまな MUA で使うための設
定集も配布していましたが、それらは後に@file{tiny-mime.el} とともに１つの 
package にまとめられ、tm という名前で配布されます。@refill

守岡 知彦 はやがて、MIME message を閲覧するためのプログラムである
@file{tm-body.el} を書きます。これは、すぐに@file{tm-view.el} という名前
に変わりましたが、やがて、これが@file{tiny-mime.el} に代わって、tm の中
核となります。@refill

@file{tm-view.el} は当然、Content-Transfer-Encoding を扱う必要があります。
この目的のために、MEL が整備されはじめました。Base64 に関しては 
@file{tiny-mime.el} の code が移され、また、新たにQuoted-Printable の 
code が追加されました。これらが@file{mel-b.el} と @file{mel-q.el} になり
ました。@refill

また、後に、守岡 知彦 によって uuencode 用の @file{mel-u.el} が追加され、
その後に、小林 修平 氏によって x-gzip64 用の@file{mel-g.el} が追加されま
した。@refill

tm では後に、守岡 知彦 によって @file{tiny-mime.el} の再実装が行われ、こ
の過程で、STD 11 の parser が書かれました。これは、現在の 
@file{std11.el} に当たります。また、この過程で @file{tiny-mime.el} は復
号化を行う @file{tm-ew-d.el} と符号化を行う @file{tm-ew-e.el} に分けられ
ました。この両者が現在の @file{eword-decode.el} と 
@file{eword-encode.el} の先祖に当たります。@refill

後に、守岡 知彦 らによって tm の全面書き換え作業が行われ、この過程で、tm 
は APEL, MEL, SEMI, EMH, RMAIL-MIME, Gnus-MIME などに分けられました。こ
のうちの MEL が FLIM の直接の先祖に当たります。@refill

後に、APEL から @file{std11.el} が移され、また、@file{mailcap.el},
@file{eword-decode.el} および @file{eword-encode.el} が SEMI から移され、
package の名前が FLIM となります。@refill

この直前から田中 哲 氏がより RFC に忠実な実装を書き始め、これは、現在、
FLIM の枝である ``FLIM-FLAM'' となっています。


@node Concept Index, Function Index, Appendix, Top
@chapter Concept Index

@printindex cp

@node Function Index, Variable Index, Concept Index, Top
@chapter Function Index

@printindex fn

@node Variable Index,  , Function Index, Top
@chapter Variable Index

@printindex vr
@bye
