X-Git-Url: http://git.hcoop.net/bpt/emacs.git/blobdiff_plain/fd897522d43b64650abd089ecb1b3a5569fbbd49..9eb82ca3889101342461041f78528857cd69f9e8:/lispref/nonascii.texi diff --git a/lispref/nonascii.texi b/lispref/nonascii.texi index e5ead72321..ba001ca72d 100644 --- a/lispref/nonascii.texi +++ b/lispref/nonascii.texi @@ -1,29 +1,33 @@ @c -*-texinfo-*- @c This is part of the GNU Emacs Lisp Reference Manual. -@c Copyright (C) 1998, 1999 Free Software Foundation, Inc. +@c Copyright (C) 1998, 1999, 2002, 2003, 2004, +@c 2005, 2006 Free Software Foundation, Inc. @c See the file elisp.texi for copying conditions. @setfilename ../info/characters @node Non-ASCII Characters, Searching and Matching, Text, Top -@chapter Non-ASCII Characters +@chapter Non-@acronym{ASCII} Characters @cindex multibyte characters -@cindex non-ASCII characters +@cindex non-@acronym{ASCII} characters - This chapter covers the special issues relating to non-@sc{ascii} + This chapter covers the special issues relating to non-@acronym{ASCII} characters and how they are stored in strings and buffers. @menu -* Text Representations:: -* Converting Representations:: -* Selecting a Representation:: -* Character Codes:: -* Character Sets:: -* Chars and Bytes:: -* Splitting Characters:: -* Scanning Charsets:: -* Translation of Characters:: -* Coding Systems:: -* Input Methods:: -* Locales:: Interacting with the POSIX locale. +* Text Representations:: Unibyte and multibyte representations +* Converting Representations:: Converting unibyte to multibyte and vice versa. +* Selecting a Representation:: Treating a byte sequence as unibyte or multi. +* Character Codes:: How unibyte and multibyte relate to + codes of individual characters. +* Character Sets:: The space of possible character codes + is divided into various character sets. +* Chars and Bytes:: More information about multibyte encodings. +* Splitting Characters:: Converting a character to its byte sequence. +* Scanning Charsets:: Which character sets are used in a buffer? +* Translation of Characters:: Translation tables are used for conversion. +* Coding Systems:: Coding systems are conversions for saving files. +* Input Methods:: Input methods allow users to enter various + non-ASCII characters without special keyboards. +* Locales:: Interacting with the POSIX locale. @end menu @node Text Representations @@ -41,8 +45,8 @@ attention to the difference. @cindex unibyte text In unibyte representation, each character occupies one byte and therefore the possible character codes range from 0 to 255. Codes 0 -through 127 are @sc{ascii} characters; the codes from 128 through 255 -are used for one non-@sc{ascii} character set (you can choose which +through 127 are @acronym{ASCII} characters; the codes from 128 through 255 +are used for one non-@acronym{ASCII} character set (you can choose which character set by setting the variable @code{nonascii-insert-offset}). @cindex leading code @@ -56,12 +60,13 @@ stored. The first byte of a multibyte character is always in the range character are always in the range 160 through 255 (octal 0240 through 0377); these values are @dfn{trailing codes}. - Some sequences of bytes do not form meaningful multibyte characters: -for example, a single isolated byte in the range 128 through 255 is -never meaningful. Such byte sequences are not entirely valid, and never -appear in proper multibyte text (since that consists of a sequence of -@emph{characters}); but they can appear as part of ``raw bytes'' -(@pxref{Explicit Encoding}). + Some sequences of bytes are not valid in multibyte text: for example, +a single isolated byte in the range 128 through 159 is not allowed. But +character codes 128 through 159 can appear in multibyte text, +represented as two-byte sequences. All the character codes 128 through +255 are possible (though slightly abnormal) in multibyte text; they +appear in multibyte buffers and strings when you do explicit encoding +and decoding (@pxref{Explicit Encoding}). In a buffer, the buffer-local value of the variable @code{enable-multibyte-characters} specifies the representation used. @@ -90,15 +95,16 @@ default value to @code{nil} early in startup. @end defvar @defun position-bytes position -@tindex position-bytes -Return the byte-position corresponding to buffer position @var{position} -in the current buffer. +Return the byte-position corresponding to buffer position +@var{position} in the current buffer. This is 1 at the start of the +buffer, and counts upward in bytes. If @var{position} is out of +range, the value is @code{nil}. @end defun @defun byte-to-position byte-position -@tindex byte-to-position Return the buffer position corresponding to byte-position -@var{byte-position} in the current buffer. +@var{byte-position} in the current buffer. If @var{byte-position} is +out of range, the value is @code{nil}. @end defun @defun multibyte-string-p string @@ -130,16 +136,16 @@ alternative, to convert the buffer contents to multibyte, is not acceptable because the buffer's representation is a choice made by the user that cannot be overridden automatically. - Converting unibyte text to multibyte text leaves @sc{ascii} characters -unchanged, and likewise 128 through 159. It converts the non-@sc{ascii} -codes 160 through 255 by adding the value @code{nonascii-insert-offset} -to each character code. By setting this variable, you specify which -character set the unibyte characters correspond to (@pxref{Character -Sets}). For example, if @code{nonascii-insert-offset} is 2048, which is -@code{(- (make-char 'latin-iso8859-1) 128)}, then the unibyte -non-@sc{ascii} characters correspond to Latin 1. If it is 2688, which -is @code{(- (make-char 'greek-iso8859-7) 128)}, then they correspond to -Greek letters. + Converting unibyte text to multibyte text leaves @acronym{ASCII} characters +unchanged, and likewise character codes 128 through 159. It converts +the non-@acronym{ASCII} codes 160 through 255 by adding the value +@code{nonascii-insert-offset} to each character code. By setting this +variable, you specify which character set the unibyte characters +correspond to (@pxref{Character Sets}). For example, if +@code{nonascii-insert-offset} is 2048, which is @code{(- (make-char +'latin-iso8859-1) 128)}, then the unibyte non-@acronym{ASCII} characters +correspond to Latin 1. If it is 2688, which is @code{(- (make-char +'greek-iso8859-7) 128)}, then they correspond to Greek letters. Converting multibyte text to unibyte is simpler: it discards all but the low 8 bits of each character code. If @code{nonascii-insert-offset} @@ -149,11 +155,11 @@ text to multibyte and back to unibyte reproduces the original unibyte text. @defvar nonascii-insert-offset -This variable specifies the amount to add to a non-@sc{ascii} character +This variable specifies the amount to add to a non-@acronym{ASCII} character when converting unibyte text to multibyte. It also applies when @code{self-insert-command} inserts a character in the unibyte -non-@sc{ascii} range, 128 through 255. However, the function -@code{insert-char} does not perform this conversion. +non-@acronym{ASCII} range, 128 through 255. However, the functions +@code{insert} and @code{insert-char} do not perform this conversion. The right value to use to select character set @var{cs} is @code{(- (make-char @var{cs}) 128)}. If the value of @@ -165,20 +171,55 @@ value for the Latin 1 character set, rather than zero. This variable provides a more general alternative to @code{nonascii-insert-offset}. You can use it to specify independently how to translate each code in the range of 128 through 255 into a -multibyte character. The value should be a vector, or @code{nil}. +multibyte character. The value should be a char-table, or @code{nil}. If this is non-@code{nil}, it overrides @code{nonascii-insert-offset}. @end defvar +The next three functions either return the argument @var{string}, or a +newly created string with no text properties. + @defun string-make-unibyte string This function converts the text of @var{string} to unibyte representation, if it isn't already, and returns the result. If -@var{string} is a unibyte string, it is returned unchanged. +@var{string} is a unibyte string, it is returned unchanged. Multibyte +character codes are converted to unibyte according to +@code{nonascii-translation-table} or, if that is @code{nil}, using +@code{nonascii-insert-offset}. If the lookup in the translation table +fails, this function takes just the low 8 bits of each character. @end defun @defun string-make-multibyte string This function converts the text of @var{string} to multibyte representation, if it isn't already, and returns the result. If -@var{string} is a multibyte string, it is returned unchanged. +@var{string} is a multibyte string or consists entirely of +@acronym{ASCII} characters, it is returned unchanged. In particular, +if @var{string} is unibyte and entirely @acronym{ASCII}, the returned +string is unibyte. (When the characters are all @acronym{ASCII}, +Emacs primitives will treat the string the same way whether it is +unibyte or multibyte.) If @var{string} is unibyte and contains +non-@acronym{ASCII} characters, the function +@code{unibyte-char-to-multibyte} is used to convert each unibyte +character to a multibyte character. +@end defun + +@defun string-to-multibyte string +This function returns a multibyte string containing the same sequence +of character codes as @var{string}. Unlike +@code{string-make-multibyte}, this function unconditionally returns a +multibyte string. If @var{string} is a multibyte string, it is +returned unchanged. +@end defun + +@defun multibyte-char-to-unibyte char +This convert the multibyte character @var{char} to a unibyte +character, based on @code{nonascii-translation-table} and +@code{nonascii-insert-offset}. +@end defun + +@defun unibyte-char-to-multibyte char +This convert the unibyte character @var{char} to a multibyte +character, based on @code{nonascii-translation-table} and +@code{nonascii-insert-offset}. @end defun @node Selecting a Representation @@ -196,7 +237,10 @@ This function leaves the buffer contents unchanged when viewed as a sequence of bytes. As a consequence, it can change the contents viewed as characters; a sequence of two bytes which is treated as one character in multibyte representation will count as two characters in unibyte -representation. +representation. Character codes 128 through 159 are an exception. They +are represented by one byte in a unibyte buffer, but when the buffer is +set to multibyte, they are converted to two-byte sequences, and vice +versa. This function sets @code{enable-multibyte-characters} to record which representation is in use. It also adjusts various data in the buffer @@ -214,7 +258,10 @@ treating each byte as a character. This means that the value may have more characters than @var{string} has. If @var{string} is already a unibyte string, then the value is -@var{string} itself. +@var{string} itself. Otherwise it is a newly created string, with no +text properties. If @var{string} is multibyte, any characters it +contains of charset @code{eight-bit-control} or @code{eight-bit-graphic} +are converted to the corresponding single byte. @end defun @defun string-as-multibyte string @@ -223,7 +270,11 @@ treating each multibyte sequence as one character. This means that the value may have fewer characters than @var{string} has. If @var{string} is already a multibyte string, then the value is -@var{string} itself. +@var{string} itself. Otherwise it is a newly created string, with no +text properties. If @var{string} is unibyte and contains any individual +8-bit bytes (i.e.@: not part of a multibyte form), they are converted to +the corresponding multibyte character of charset @code{eight-bit-control} +or @code{eight-bit-graphic}. @end defun @node Character Codes @@ -234,14 +285,15 @@ If @var{string} is already a multibyte string, then the value is codes. The valid character codes for unibyte representation range from 0 to 255---the values that can fit in one byte. The valid character codes for multibyte representation range from 0 to 524287, but not all -values in that range are valid. In particular, the values 128 through -255 are not legitimate in multibyte text (though they can occur in ``raw -bytes''; @pxref{Explicit Encoding}). Only the @sc{ascii} codes 0 -through 127 are fully legitimate in both representations. +values in that range are valid. The values 128 through 255 are not +entirely proper in multibyte text, but they can occur if you do explicit +encoding and decoding (@pxref{Explicit Encoding}). Some other character +codes cannot occur at all in multibyte text. Only the @acronym{ASCII} codes +0 through 127 are completely legitimate in both representations. -@defun char-valid-p charcode -This returns @code{t} if @var{charcode} is valid for either one of the two -text representations. +@defun char-valid-p charcode &optional genericp +This returns @code{t} if @var{charcode} is valid (either for unibyte +text or for multibyte text). @example (char-valid-p 65) @@ -251,6 +303,10 @@ text representations. (char-valid-p 2248) @result{} t @end example + +If the optional argument @var{genericp} is non-@code{nil}, this +function also returns @code{t} if @var{charcode} is a generic +character (@pxref{Splitting Characters}). @end defun @node Character Sets @@ -270,29 +326,43 @@ into several character sets. For example, one set of Chinese characters, generally known as Big 5, is divided into two Emacs character sets, @code{chinese-big5-1} and @code{chinese-big5-2}. + @acronym{ASCII} characters are in character set @code{ascii}. The +non-@acronym{ASCII} characters 128 through 159 are in character set +@code{eight-bit-control}, and codes 160 through 255 are in character set +@code{eight-bit-graphic}. + @defun charsetp object Returns @code{t} if @var{object} is a symbol that names a character set, @code{nil} otherwise. @end defun +@defvar charset-list +The value is a list of all defined character set names. +@end defvar + @defun charset-list -This function returns a list of all defined character set names. +This function returns the value of @code{charset-list}. It is only +provided for backward compatibility. @end defun @defun char-charset character This function returns the name of the character set that @var{character} -belongs to. +belongs to, or the symbol @code{unknown} if @var{character} is not a +valid character. @end defun @defun charset-plist charset -@tindex charset-plist This function returns the charset property list of the character set @var{charset}. Although @var{charset} is a symbol, this is not the same as the property list of that symbol. Charset properties are used for -special purposes within Emacs; for example, @code{x-charset-registry} -helps determine which fonts to use (@pxref{Font Selection}). +special purposes within Emacs. @end defun +@deffn Command list-charset-chars charset +This command displays a list of characters in the character set +@var{charset}. +@end deffn + @node Chars and Bytes @section Characters and Bytes @cindex bytes and characters @@ -301,13 +371,14 @@ helps determine which fonts to use (@pxref{Font Selection}). @cindex dimension (of character set) In multibyte representation, each character occupies one or more bytes. Each character set has an @dfn{introduction sequence}, which is -normally one or two bytes long. (Exception: the @sc{ascii} character -set has a zero-length introduction sequence.) The introduction sequence -is the beginning of the byte sequence for any character in the character -set. The rest of the character's bytes distinguish it from the other -characters in the same character set. Depending on the character set, -there are either one or two distinguishing bytes; the number of such -bytes is called the @dfn{dimension} of the character set. +normally one or two bytes long. (Exception: the @code{ascii} character +set and the @code{eight-bit-graphic} character set have a zero-length +introduction sequence.) The introduction sequence is the beginning of +the byte sequence for any character in the character set. The rest of +the character's bytes distinguish it from the other characters in the +same character set. Depending on the character set, there are either +one or two distinguishing bytes; the number of such bytes is called the +@dfn{dimension} of the character set. @defun charset-dimension charset This function returns the dimension of @var{charset}; at present, the @@ -315,7 +386,6 @@ dimension is always 1 or 2. @end defun @defun charset-bytes charset -@tindex charset-bytes This function returns the number of bytes used to represent a character in character set @var{charset}. @end defun @@ -342,33 +412,35 @@ Return a list containing the name of the character set of identify @var{character} within that character set. The number of byte values is the character set's dimension. +If @var{character} is invalid as a character code, @code{split-char} +returns a list consisting of the symbol @code{unknown} and @var{character}. + @example (split-char 2248) @result{} (latin-iso8859-1 72) (split-char 65) @result{} (ascii 65) -@end example - -Unibyte non-@sc{ascii} characters are considered as part of -the @code{ascii} character set: - -@example -(split-char 192) - @result{} (ascii 192) +(split-char 128) + @result{} (eight-bit-control 128) @end example @end defun -@defun make-char charset &rest byte-values -This function returns the character in character set @var{charset} -identified by @var{byte-values}. This is roughly the inverse of -@code{split-char}. Normally, you should specify either one or two -@var{byte-values}, according to the dimension of @var{charset}. For -example, +@defun make-char charset &optional code1 code2 +This function returns the character in character set @var{charset} whose +position codes are @var{code1} and @var{code2}. This is roughly the +inverse of @code{split-char}. Normally, you should specify either one +or both of @var{code1} and @var{code2} according to the dimension of +@var{charset}. For example, @example (make-char 'latin-iso8859-1 72) @result{} 2248 @end example + +Actually, the eighth bit of both @var{code1} and @var{code2} is zeroed +before they are used to index @var{charset}. Thus you may use, for +instance, an ISO 8859 character code rather than subtracting 128, as +is necessary to index the corresponding Emacs charset. @end defun @cindex generic characters @@ -385,10 +457,18 @@ For example: @result{} 2176 (char-valid-p 2176) @result{} nil +(char-valid-p 2176 t) + @result{} t (split-char 2176) @result{} (latin-iso8859-1 0) @end example +The character sets @code{ascii}, @code{eight-bit-control}, and +@code{eight-bit-graphic} don't have corresponding generic characters. If +@var{charset} is one of them and you don't supply @var{code1}, +@code{make-char} returns the character code corresponding to the +smallest code in @var{charset}. + @node Scanning Charsets @section Scanning for Character Sets @@ -397,6 +477,13 @@ part of a buffer or a string. One use for this is in determining which coding systems (@pxref{Coding Systems}) are capable of representing all of the text in question. +@defun charset-after &optional pos +This function return the charset of a character in the current buffer +at position @var{pos}. If @var{pos} is omitted or @code{nil}, it +defaults to the current value of point. If @var{pos} is out of range, +the value is @code{nil}. +@end defun + @defun find-charset-region beg end &optional translation This function returns a list of the character sets that appear in the current buffer between positions @var{beg} and @var{end}. @@ -406,17 +493,6 @@ be used in scanning the text (@pxref{Translation of Characters}). If it is non-@code{nil}, then each character in the region is translated through this table, and the value returned describes the translated characters instead of the characters actually in the buffer. - -In two peculiar cases, the value includes the symbol @code{unknown}: - -@itemize @bullet -@item -When a unibyte buffer contains non-@sc{ascii} characters. - -@item -When a multibyte buffer contains invalid byte-sequences (raw bytes). -@xref{Explicit Encoding}. -@end itemize @end defun @defun find-charset-string string &optional translation @@ -431,40 +507,58 @@ current buffer. @cindex character translation tables @cindex translation tables - A @dfn{translation table} specifies a mapping of characters -into characters. These tables are used in encoding and decoding, and -for other purposes. Some coding systems specify their own particular -translation tables; there are also default translation tables which -apply to all other coding systems. + A @dfn{translation table} is a char-table that specifies a mapping +of characters into characters. These tables are used in encoding and +decoding, and for other purposes. Some coding systems specify their +own particular translation tables; there are also default translation +tables which apply to all other coding systems. + + For instance, the coding-system @code{utf-8} has a translation table +that maps characters of various charsets (e.g., +@code{latin-iso8859-@var{x}}) into Unicode character sets. This way, +it can encode Latin-2 characters into UTF-8. Meanwhile, +@code{unify-8859-on-decoding-mode} operates by specifying +@code{standard-translation-table-for-decode} to translate +Latin-@var{x} characters into corresponding Unicode characters. @defun make-translation-table &rest translations This function returns a translation table based on the argument -@var{translations}. Each element of -@var{translations} should be a list of the form @code{(@var{from} -. @var{to})}; this says to translate the character @var{from} into -@var{to}. +@var{translations}. Each element of @var{translations} should be a +list of elements of the form @code{(@var{from} . @var{to})}; this says +to translate the character @var{from} into @var{to}. + +The arguments and the forms in each argument are processed in order, +and if a previous form already translates @var{to} to some other +character, say @var{to-alt}, @var{from} is also translated to +@var{to-alt}. You can also map one whole character set into another character set with the same dimension. To do this, you specify a generic character (which designates a character set) for @var{from} (@pxref{Splitting Characters}). -In this case, @var{to} should also be a generic character, for another -character set of the same dimension. Then the translation table -translates each character of @var{from}'s character set into the -corresponding character of @var{to}'s character set. +In this case, if @var{to} is also a generic character, its character +set should have the same dimension as @var{from}'s. Then the +translation table translates each character of @var{from}'s character +set into the corresponding character of @var{to}'s character set. If +@var{from} is a generic character and @var{to} is an ordinary +character, then the translation table translates every character of +@var{from}'s character set into @var{to}. @end defun In decoding, the translation table's translations are applied to the characters that result from ordinary decoding. If a coding system has -property @code{character-translation-table-for-decode}, that specifies -the translation table to use. Otherwise, if -@code{standard-translation-table-for-decode} is non-@code{nil}, decoding -uses that table. +property @code{translation-table-for-decode}, that specifies the +translation table to use. (This is a property of the coding system, +as returned by @code{coding-system-get}, not a property of the symbol +that is the coding system's name. @xref{Coding System Basics,, Basic +Concepts of Coding Systems}.) Otherwise, if +@code{standard-translation-table-for-decode} is non-@code{nil}, +decoding uses that table. In encoding, the translation table's translations are applied to the characters in the buffer, and the result of translation is actually encoded. If a coding system has property -@code{character-translation-table-for-encode}, that specifies the -translation table to use. Otherwise the variable +@code{translation-table-for-encode}, that specifies the translation +table to use. Otherwise the variable @code{standard-translation-table-for-encode} specifies the translation table. @@ -478,6 +572,18 @@ This is the default translation table for encoding, for coding systems that don't specify any other translation table. @end defvar +@defvar translation-table-for-input +Self-inserting characters are translated through this translation +table before they are inserted. Search commands also translate their +input through this table, so they can compare more reliably with +what's in the buffer. + +@code{set-buffer-file-coding-system} sets this variable so that your +keyboard input gets translated into the character sets that the buffer +is likely to contain. This variable automatically becomes +buffer-local when set. +@end defvar + @node Coding Systems @section Coding Systems @@ -491,15 +597,17 @@ by a particular @dfn{coding system}. documented here. @menu -* Coding System Basics:: -* Encoding and I/O:: -* Lisp and Coding Systems:: -* User-Chosen Coding Systems:: -* Default Coding Systems:: -* Specifying Coding Systems:: -* Explicit Encoding:: -* Terminal I/O Encoding:: -* MS-DOS File Types:: +* Coding System Basics:: Basic concepts. +* Encoding and I/O:: How file I/O functions handle coding systems. +* Lisp and Coding Systems:: Functions to operate on coding system names. +* User-Chosen Coding Systems:: Asking the user to choose a coding system. +* Default Coding Systems:: Controlling the default choices. +* Specifying Coding Systems:: Requesting a particular coding system + for a single file operation. +* Explicit Encoding:: Encoding or decoding text without doing I/O. +* Terminal I/O Encoding:: Use of encoding for terminal I/O. +* MS-DOS File Types:: How DOS "text" and "binary" files + relate to coding systems. @end menu @node Coding System Basics @@ -519,6 +627,27 @@ characters; for example, there are three coding systems for the Cyrillic conversion, but some of them leave the choice unspecified---to be chosen heuristically for each file, based on the data. + In general, a coding system doesn't guarantee roundtrip identity: +decoding a byte sequence using coding system, then encoding the +resulting text in the same coding system, can produce a different byte +sequence. However, the following coding systems do guarantee that the +byte sequence will be the same as what you originally decoded: + +@quotation +chinese-big5 chinese-iso-8bit cyrillic-iso-8bit emacs-mule +greek-iso-8bit hebrew-iso-8bit iso-latin-1 iso-latin-2 iso-latin-3 +iso-latin-4 iso-latin-5 iso-latin-8 iso-latin-9 iso-safe +japanese-iso-8bit japanese-shift-jis korean-iso-8bit raw-text +@end quotation + + Encoding buffer text and then decoding the result can also fail to +reproduce the original text. For instance, if you encode Latin-2 +characters with @code{utf-8} and decode the result using the same +coding system, you'll get Unicode characters (of charset +@code{mule-unicode-0100-24ff}). If you encode Unicode characters with +@code{iso-latin-2} and decode the result with the same coding system, +you'll get Latin-2 characters. + @cindex end of line conversion @dfn{End of line conversion} handles three different conventions used on various systems for representing end of line in files. The Unix @@ -577,7 +706,7 @@ a coding system for decoding the file data, and @code{write-region} uses one to encode the buffer contents. You can specify the coding system to use either explicitly -(@pxref{Specifying Coding Systems}), or implicitly using the defaulting +(@pxref{Specifying Coding Systems}), or implicitly using a default mechanism (@pxref{Default Coding Systems}). But these methods may not completely specify what to do. For example, they may choose a coding system such as @code{undefined} which leaves the character code @@ -586,27 +715,33 @@ operation finishes the job of choosing a coding system. Very often you will want to find out afterwards which coding system was chosen. @defvar buffer-file-coding-system -This variable records the coding system that was used for visiting the -current buffer. It is used for saving the buffer, and for writing part -of the buffer with @code{write-region}. When those operations ask the -user to specify a different coding system, -@code{buffer-file-coding-system} is updated to the coding system -specified. - -However, @code{buffer-file-coding-system} does not affect sending text +This buffer-local variable records the coding system that was used to visit +the current buffer. It is used for saving the buffer, and for writing part +of the buffer with @code{write-region}. If the text to be written +cannot be safely encoded using the coding system specified by this +variable, these operations select an alternative encoding by calling +the function @code{select-safe-coding-system} (@pxref{User-Chosen +Coding Systems}). If selecting a different encoding requires to ask +the user to specify a coding system, @code{buffer-file-coding-system} +is updated to the newly selected coding system. + +@code{buffer-file-coding-system} does @emph{not} affect sending text to a subprocess. @end defvar @defvar save-buffer-coding-system -This variable specifies the coding system for saving the buffer---but it -is not used for @code{write-region}. +This variable specifies the coding system for saving the buffer (by +overriding @code{buffer-file-coding-system}). Note that it is not used +for @code{write-region}. When a command to save the buffer starts out to use -@code{save-buffer-coding-system}, and that coding system cannot handle +@code{buffer-file-coding-system} (or @code{save-buffer-coding-system}), +and that coding system cannot handle the actual text in the buffer, the command asks the user to choose -another coding system. After that happens, the command also updates -@code{save-buffer-coding-system} to represent the coding system that the -user specified. +another coding system (by calling @code{select-safe-coding-system}). +After that happens, the command also updates +@code{buffer-file-coding-system} to represent the coding system that +the user specified. @end defvar @defvar last-coding-system-used @@ -623,6 +758,26 @@ interested in. The variable @code{selection-coding-system} specifies how to encode selections for the window system. @xref{Window System Selections}. +@defvar file-name-coding-system +The variable @code{file-name-coding-system} specifies the coding +system to use for encoding file names. Emacs encodes file names using +that coding system for all file operations. If +@code{file-name-coding-system} is @code{nil}, Emacs uses a default +coding system determined by the selected language environment. In the +default language environment, any non-@acronym{ASCII} characters in +file names are not encoded specially; they appear in the file system +using the internal Emacs representation. +@end defvar + + @strong{Warning:} if you change @code{file-name-coding-system} (or +the language environment) in the middle of an Emacs session, problems +can result if you have already visited files whose names were encoded +using the earlier coding system and are handled differently under the +new coding system. If you try to save one of these buffers under the +visited file name, saving may use the wrong file name, or it may get +an error. If such a problem happens, use @kbd{C-x C-w} to specify a +new file name for that buffer. + @node Lisp and Coding Systems @subsection Coding Systems in Lisp @@ -631,12 +786,13 @@ selections for the window system. @xref{Window System Selections}. @defun coding-system-list &optional base-only This function returns a list of all coding system names (symbols). If @var{base-only} is non-@code{nil}, the value includes only the -base coding systems. Otherwise, it includes variant coding systems as well. +base coding systems. Otherwise, it includes alias and variant coding +systems as well. @end defun @defun coding-system-p object This function returns @code{t} if @var{object} is a coding system -name. +name or @code{nil}. @end defun @defun check-coding-system coding-system @@ -645,12 +801,44 @@ If that is valid, it returns @var{coding-system}. Otherwise it signals an error with condition @code{coding-system-error}. @end defun +@cindex EOL conversion +@cindex end-of-line conversion +@cindex line end conversion +@defun coding-system-eol-type coding-system +This function returns the type of end-of-line (a.k.a.@: @dfn{eol}) +conversion used by @var{coding-system}. If @var{coding-system} +specifies a certain eol conversion, the return value is an integer 0, +1, or 2, standing for @code{unix}, @code{dos}, and @code{mac}, +respectively. If @var{coding-system} doesn't specify eol conversion +explicitly, the return value is a vector of coding systems, each one +with one of the possible eol conversion types, like this: + +@lisp +(coding-system-eol-type 'latin-1) + @result{} [latin-1-unix latin-1-dos latin-1-mac] +@end lisp + +@noindent +If this function returns a vector, Emacs will decide, as part of the +text encoding or decoding process, what eol conversion to use. For +decoding, the end-of-line format of the text is auto-detected, and the +eol conversion is set to match it (e.g., DOS-style CRLF format will +imply @code{dos} eol conversion). For encoding, the eol conversion is +taken from the appropriate default coding system (e.g., +@code{default-buffer-file-coding-system} for +@code{buffer-file-coding-system}), or from the default eol conversion +appropriate for the underlying platform. +@end defun + @defun coding-system-change-eol-conversion coding-system eol-type This function returns a coding system which is like @var{coding-system} except for its eol conversion, which is specified by @code{eol-type}. @var{eol-type} should be @code{unix}, @code{dos}, @code{mac}, or @code{nil}. If it is @code{nil}, the returned coding system determines the end-of-line conversion from the data. + +@var{eol-type} may also be 0, 1 or 2, standing for @code{unix}, +@code{dos} and @code{mac}, respectively. @end defun @defun coding-system-change-text-conversion eol-coding text-coding @@ -685,7 +873,7 @@ encode all the character sets in the list @var{charsets}. @defun detect-coding-region start end &optional highest This function chooses a plausible coding system for decoding the text -from @var{start} to @var{end}. This text should be ``raw bytes'' +from @var{start} to @var{end}. This text should be a byte sequence (@pxref{Explicit Encoding}). Normally this function returns a list of coding systems that could @@ -694,37 +882,81 @@ decreasing priority. But if @var{highest} is non-@code{nil}, then the return value is just one coding system, the one that is highest in priority. -If the region contains only @sc{ascii} characters, the value -is @code{undecided} or @code{(undecided)}. +If the region contains only @acronym{ASCII} characters except for such +ISO-2022 control characters ISO-2022 as @code{ESC}, the value is +@code{undecided} or @code{(undecided)}, or a variant specifying +end-of-line conversion, if that can be deduced from the text. @end defun -@defun detect-coding-string string highest +@defun detect-coding-string string &optional highest This function is like @code{detect-coding-region} except that it operates on the contents of @var{string} instead of bytes in the buffer. @end defun - @xref{Process Information}, for how to examine or set the coding -systems used for I/O to a subprocess. + @xref{Coding systems for a subprocess,, Process Information}, in +particular the description of the functions +@code{process-coding-system} and @code{set-process-coding-system}, for +how to examine or set the coding systems used for I/O to a subprocess. @node User-Chosen Coding Systems @subsection User-Chosen Coding Systems -@defun select-safe-coding-system from to &optional preferred-coding-system -This function selects a coding system for encoding the text between -@var{from} and @var{to}, asking the user to choose if necessary. - -The optional argument @var{preferred-coding-system} specifies a coding -system to try first. If that one can handle the text in the specified -region, then it is used. If this argument is omitted, the current -buffer's value of @code{buffer-file-coding-system} is tried first. - -If the region contains some multibyte characters that the preferred -coding system cannot encode, this function asks the user to choose from -a list of coding systems which can encode the text, and returns the -user's choice. - -One other kludgy feature: if @var{from} is a string, the string is the -target text, and @var{to} is ignored. +@cindex select safe coding system +@defun select-safe-coding-system from to &optional default-coding-system accept-default-p file +This function selects a coding system for encoding specified text, +asking the user to choose if necessary. Normally the specified text +is the text in the current buffer between @var{from} and @var{to}. If +@var{from} is a string, the string specifies the text to encode, and +@var{to} is ignored. + +If @var{default-coding-system} is non-@code{nil}, that is the first +coding system to try; if that can handle the text, +@code{select-safe-coding-system} returns that coding system. It can +also be a list of coding systems; then the function tries each of them +one by one. After trying all of them, it next tries the current +buffer's value of @code{buffer-file-coding-system} (if it is not +@code{undecided}), then the value of +@code{default-buffer-file-coding-system} and finally the user's most +preferred coding system, which the user can set using the command +@code{prefer-coding-system} (@pxref{Recognize Coding,, Recognizing +Coding Systems, emacs, The GNU Emacs Manual}). + +If one of those coding systems can safely encode all the specified +text, @code{select-safe-coding-system} chooses it and returns it. +Otherwise, it asks the user to choose from a list of coding systems +which can encode all the text, and returns the user's choice. + +@var{default-coding-system} can also be a list whose first element is +t and whose other elements are coding systems. Then, if no coding +system in the list can handle the text, @code{select-safe-coding-system} +queries the user immediately, without trying any of the three +alternatives described above. + +The optional argument @var{accept-default-p}, if non-@code{nil}, +should be a function to determine whether a coding system selected +without user interaction is acceptable. @code{select-safe-coding-system} +calls this function with one argument, the base coding system of the +selected coding system. If @var{accept-default-p} returns @code{nil}, +@code{select-safe-coding-system} rejects the silently selected coding +system, and asks the user to select a coding system from a list of +possible candidates. + +@vindex select-safe-coding-system-accept-default-p +If the variable @code{select-safe-coding-system-accept-default-p} is +non-@code{nil}, its value overrides the value of +@var{accept-default-p}. + +As a final step, before returning the chosen coding system, +@code{select-safe-coding-system} checks whether that coding system is +consistent with what would be selected if the contents of the region +were read from a file. (If not, this could lead to data corruption in +a file subsequently re-visited and edited.) Normally, +@code{select-safe-coding-system} uses @code{buffer-file-name} as the +file for this purpose, but if @var{file} is non-@code{nil}, it uses +that file instead (this can be relevant for @code{write-region} and +similar functions). If it detects an apparent inconsistency, +@code{select-safe-coding-system} queries the user before selecting the +coding system. @end defun Here are two functions you can use to let the user specify a coding @@ -758,6 +990,18 @@ don't change these variables; instead, override them using @code{coding-system-for-read} and @code{coding-system-for-write} (@pxref{Specifying Coding Systems}). +@defvar auto-coding-regexp-alist +This variable is an alist of text patterns and corresponding coding +systems. Each element has the form @code{(@var{regexp} +. @var{coding-system})}; a file whose first few kilobytes match +@var{regexp} is decoded with @var{coding-system} when its contents are +read into a buffer. The settings in this alist take priority over +@code{coding:} tags in the files and the contents of +@code{file-coding-system-alist} (see below). The default value is set +so that Emacs automatically recognizes mail files in Babyl format and +reads them with no code conversions. +@end defvar + @defvar file-coding-system-alist This variable is an alist that specifies the coding systems to use for reading and writing particular files. Each element has the form @@ -773,9 +1017,11 @@ that coding system is used for both reading the file and writing it. If specifies the coding system for decoding, and its @sc{cdr} specifies the coding system for encoding. -If @var{coding} is a function name, the function must return a coding -system or a cons cell containing two coding systems. This value is used -as described above. +If @var{coding} is a function name, the function should take one +argument, a list of all arguments passed to +@code{find-operation-coding-system}. It must return a coding system +or a cons cell containing two coding systems. This value has the same +meaning as described above. @end defvar @defvar process-coding-system-alist @@ -820,13 +1066,29 @@ The value should be a cons cell of the form @code{(@var{input-coding} the subprocess, and @var{output-coding} applies to output to it. @end defvar +@defvar auto-coding-functions +This variable holds a list of functions that try to determine a +coding system for a file based on its undecoded contents. + +Each function in this list should be written to look at text in the +current buffer, but should not modify it in any way. The buffer will +contain undecoded text of parts of the file. Each function should +take one argument, @var{size}, which tells it how many characters to +look at, starting from point. If the function succeeds in determining +a coding system for the file, it should return that coding system. +Otherwise, it should return @code{nil}. + +If a file has a @samp{coding:} tag, that takes precedence, so these +functions won't be called. +@end defvar + @defun find-operation-coding-system operation &rest arguments This function returns the coding system to use (by default) for performing @var{operation} with @var{arguments}. The value has this form: @example -(@var{decoding-system} @var{encoding-system}) +(@var{decoding-system} . @var{encoding-system}) @end example The first element, @var{decoding-system}, is the coding system to use @@ -834,24 +1096,35 @@ for decoding (in case @var{operation} does decoding), and @var{encoding-system} is the coding system for encoding (in case @var{operation} does encoding). -The argument @var{operation} should be a symbol, one of -@code{insert-file-contents}, @code{write-region}, @code{call-process}, -@code{call-process-region}, @code{start-process}, or -@code{open-network-stream}. These are the names of the Emacs I/O primitives -that can do coding system conversion. +The argument @var{operation} should be a symbol, any one of +@code{insert-file-contents}, @code{write-region}, +@code{start-process}, @code{call-process}, @code{call-process-region}, +or @code{open-network-stream}. These are the names of the Emacs I/O +primitives that can do character code and eol conversion. The remaining arguments should be the same arguments that might be given -to that I/O primitive. Depending on the primitive, one of those -arguments is selected as the @dfn{target}. For example, if +to the corresponding I/O primitive. Depending on the primitive, one +of those arguments is selected as the @dfn{target}. For example, if @var{operation} does file I/O, whichever argument specifies the file name is the target. For subprocess primitives, the process name is the target. For @code{open-network-stream}, the target is the service name or port number. -This function looks up the target in @code{file-coding-system-alist}, -@code{process-coding-system-alist}, or -@code{network-coding-system-alist}, depending on @var{operation}. -@xref{Default Coding Systems}. +Depending on @var{operation}, this function looks up the target in +@code{file-coding-system-alist}, @code{process-coding-system-alist}, +or @code{network-coding-system-alist}. If the target is found in the +alist, @code{find-operation-coding-system} returns its association in +the alist; otherwise it returns @code{nil}. + +If @var{operation} is @code{insert-file-contents}, the argument +corresponding to the target may be a cons cell of the form +@code{(@var{filename} . @var{buffer})}). In that case, @var{filename} +is a file name to look up in @code{file-coding-system-alist}, and +@var{buffer} is a buffer that contains the file's contents (not yet +decoded). If @code{file-coding-system-alist} specifies a function to +call for this file, and that function needs to examine the file's +contents (as it usually does), it should examine the contents of +@var{buffer} instead of reading the file. @end defun @node Specifying Coding Systems @@ -878,8 +1151,8 @@ of the right way to use the variable: @example ;; @r{Read the file with no character code conversion.} -;; @r{Assume @sc{crlf} represents end-of-line.} -(let ((coding-system-for-write 'emacs-mule-dos)) +;; @r{Assume @acronym{crlf} represents end-of-line.} +(let ((coding-system-for-read 'emacs-mule-dos)) (insert-file-contents filename)) @end example @@ -918,90 +1191,78 @@ ability to use a coding system to encode or decode the text. You can also explicitly encode and decode text using the functions in this section. -@cindex raw bytes The result of encoding, and the input to decoding, are not ordinary -text. They are ``raw bytes''---bytes that represent text in the same -way that an external file would. When a buffer contains raw bytes, it -is most natural to mark that buffer as using unibyte representation, -using @code{set-buffer-multibyte} (@pxref{Selecting a Representation}), -but this is not required. If the buffer's contents are only temporarily -raw, leave the buffer multibyte, which will be correct after you decode -them. - - The usual way to get raw bytes in a buffer, for explicit decoding, is -to read them from a file with @code{insert-file-contents-literally} -(@pxref{Reading from Files}) or specify a non-@code{nil} @var{rawfile} -argument when visiting a file with @code{find-file-noselect}. - - The usual way to use the raw bytes that result from explicitly -encoding text is to copy them to a file or process---for example, to -write them with @code{write-region} (@pxref{Writing to Files}), and -suppress encoding for that @code{write-region} call by binding -@code{coding-system-for-write} to @code{no-conversion}. - - Raw bytes typically contain stray individual bytes with values in the -range 128 through 255, that are legitimate only as part of multibyte -sequences. Even if the buffer is multibyte, Emacs treats each such -individual byte as a character and uses the byte value as its character -code. In this way, character codes 128 through 255 can be found in a -multibyte buffer, even though they are not legitimate multibyte -character codes. - - Raw bytes sometimes contain overlong byte-sequences that look like a -proper multibyte character plus extra superfluous trailing codes. For -most purposes, Emacs treats such a sequence in a buffer or string as a -single character, and if you look at its character code, you get the -value that corresponds to the multibyte character -sequence---disregarding the extra trailing codes. This is not quite -clean, but raw bytes are used only in limited ways, so as a practical -matter it is not worth the trouble to treat this case differently. - - When a multibyte buffer contains illegitimate byte sequences, -sometimes insertion or deletion can cause them to coalesce into a -legitimate multibyte character. For example, suppose the buffer -contains the sequence 129 68 192, 68 being the character @samp{D}. If -you delete the @samp{D}, the bytes 129 and 192 become adjacent, and thus -become one multibyte character (Latin-1 A with grave accent). Point -moves to one side or the other of the character, since it cannot be -within a character. Don't be alarmed by this. - - Some really peculiar situations prevent proper coalescence. For -example, if you narrow the buffer so that the accessible portion begins -just before the @samp{D}, then delete the @samp{D}, the two surrounding -bytes cannot coalesce because one of them is outside the accessible -portion of the buffer. In this case, the deletion cannot be done, so -@code{delete-region} signals an error. +text. They logically consist of a series of byte values; that is, a +series of characters whose codes are in the range 0 through 255. In a +multibyte buffer or string, character codes 128 through 159 are +represented by multibyte sequences, but this is invisible to Lisp +programs. + + The usual way to read a file into a buffer as a sequence of bytes, so +you can decode the contents explicitly, is with +@code{insert-file-contents-literally} (@pxref{Reading from Files}); +alternatively, specify a non-@code{nil} @var{rawfile} argument when +visiting a file with @code{find-file-noselect}. These methods result in +a unibyte buffer. + + The usual way to use the byte sequence that results from explicitly +encoding text is to copy it to a file or process---for example, to write +it with @code{write-region} (@pxref{Writing to Files}), and suppress +encoding by binding @code{coding-system-for-write} to +@code{no-conversion}. Here are the functions to perform explicit encoding or decoding. The -decoding functions produce ``raw bytes''; the encoding functions are -meant to operate on ``raw bytes''. All of these functions discard text -properties. +encoding functions produce sequences of bytes; the decoding functions +are meant to operate on sequences of bytes. All of these functions +discard text properties. -@defun encode-coding-region start end coding-system -This function encodes the text from @var{start} to @var{end} according +@deffn Command encode-coding-region start end coding-system +This command encodes the text from @var{start} to @var{end} according to coding system @var{coding-system}. The encoded text replaces the -original text in the buffer. The result of encoding is ``raw bytes,'' -but the buffer remains multibyte if it was multibyte before. -@end defun +original text in the buffer. The result of encoding is logically a +sequence of bytes, but the buffer remains multibyte if it was multibyte +before. + +This command returns the length of the encoded text. +@end deffn -@defun encode-coding-string string coding-system +@defun encode-coding-string string coding-system &optional nocopy This function encodes the text in @var{string} according to coding system @var{coding-system}. It returns a new string containing the -encoded text. The result of encoding is a unibyte string of ``raw bytes.'' +encoded text, except when @var{nocopy} is non-@code{nil}, in which +case the function may return @var{string} itself if the encoding +operation is trivial. The result of encoding is a unibyte string. @end defun -@defun decode-coding-region start end coding-system -This function decodes the text from @var{start} to @var{end} according +@deffn Command decode-coding-region start end coding-system +This command decodes the text from @var{start} to @var{end} according to coding system @var{coding-system}. The decoded text replaces the original text in the buffer. To make explicit decoding useful, the text -before decoding ought to be ``raw bytes.'' -@end defun +before decoding ought to be a sequence of byte values, but both +multibyte and unibyte buffers are acceptable. + +This command returns the length of the decoded text. +@end deffn -@defun decode-coding-string string coding-system +@defun decode-coding-string string coding-system &optional nocopy This function decodes the text in @var{string} according to coding system @var{coding-system}. It returns a new string containing the -decoded text. To make explicit decoding useful, the contents of -@var{string} ought to be ``raw bytes.'' +decoded text, except when @var{nocopy} is non-@code{nil}, in which +case the function may return @var{string} itself if the decoding +operation is trivial. To make explicit decoding useful, the contents +of @var{string} ought to be a sequence of byte values, but a multibyte +string is acceptable. +@end defun + +@defun decode-coding-inserted-region from to filename &optional visit beg end replace +This function decodes the text from @var{from} to @var{to} as if +it were being read from file @var{filename} using @code{insert-file-contents} +using the rest of the arguments provided. + +The normal way to use this function is after reading text from a file +without decoding, if you decide you would rather have decoded it. +Instead of deleting the text and reading it again, this time with +decoding, you can call this function. @end defun @node Terminal I/O Encoding @@ -1018,22 +1279,22 @@ This function returns the coding system that is in use for decoding keyboard input---or @code{nil} if no coding system is to be used. @end defun -@defun set-keyboard-coding-system coding-system -This function specifies @var{coding-system} as the coding system to +@deffn Command set-keyboard-coding-system coding-system +This command specifies @var{coding-system} as the coding system to use for decoding keyboard input. If @var{coding-system} is @code{nil}, that means do not decode keyboard input. -@end defun +@end deffn @defun terminal-coding-system This function returns the coding system that is in use for encoding terminal output---or @code{nil} for no encoding. @end defun -@defun set-terminal-coding-system coding-system -This function specifies @var{coding-system} as the coding system to use +@deffn Command set-terminal-coding-system coding-system +This command specifies @var{coding-system} as the coding system to use for encoding terminal output. If @var{coding-system} is @code{nil}, that means do not encode terminal output. -@end defun +@end deffn @node MS-DOS File Types @subsection MS-DOS File Types @@ -1046,7 +1307,7 @@ that means do not encode terminal output. On MS-DOS and Microsoft Windows, Emacs guesses the appropriate end-of-line conversion for a file by looking at the file's name. This -feature classifies fils as @dfn{text files} and @dfn{binary files}. By +feature classifies files as @dfn{text files} and @dfn{binary files}. By ``binary file'' we mean a file of literal byte values that are not necessarily meant to be characters; Emacs does no end-of-line conversion and no character code conversion for them. On the other hand, the bytes @@ -1098,9 +1359,9 @@ from the file contents, in the usual Emacs fashion. @section Input Methods @cindex input methods - @dfn{Input methods} provide convenient ways of entering non-@sc{ascii} + @dfn{Input methods} provide convenient ways of entering non-@acronym{ASCII} characters from the keyboard. Unlike coding systems, which translate -non-@sc{ascii} characters to and from encodings meant to be read by +non-@acronym{ASCII} characters to and from encodings meant to be read by programs, input methods provide human-friendly commands. (@xref{Input Methods,,, emacs, The GNU Emacs Manual}, for information on how users use input methods to enter text.) How to define input methods is not @@ -1116,18 +1377,18 @@ in any fashion.) It is @code{nil} if no input method is active in the buffer now. @end defvar -@defvar default-input-method +@defopt default-input-method This variable holds the default input method for commands that choose an input method. Unlike @code{current-input-method}, this variable is normally global. -@end defvar +@end defopt -@defun set-input-method input-method -This function activates input method @var{input-method} for the current +@deffn Command set-input-method input-method +This command activates input method @var{input-method} for the current buffer. It also sets @code{default-input-method} to @var{input-method}. -If @var{input-method} is @code{nil}, this function deactivates any input +If @var{input-method} is @code{nil}, this command deactivates any input method for the current buffer. -@end defun +@end deffn @defun read-input-method-name prompt &optional default inhibit-null This function reads an input method name with the minibuffer, prompting @@ -1152,18 +1413,19 @@ Here @var{input-method} is the input method name, a string; environment this input method is recommended for. (That serves only for documentation purposes.) -@var{title} is a string to display in the mode line while this method is -active. @var{description} is a string describing this method and what -it is good for. - @var{activate-func} is a function to call to activate this method. The @var{args}, if any, are passed as arguments to @var{activate-func}. All told, the arguments to @var{activate-func} are @var{input-method} and the @var{args}. + +@var{title} is a string to display in the mode line while this method is +active. @var{description} is a string describing this method and what +it is good for. @end defvar The fundamental interface to input methods is through the -variable @code{input-method-function}. @xref{Reading One Event}. +variable @code{input-method-function}. @xref{Reading One Event}, +and @ref{Invoking the Input Method}. @node Locales @section Locales @@ -1174,26 +1436,57 @@ to use in language-related features. These Emacs variables control how Emacs interacts with these features. @defvar locale-coding-system -@tindex locale-coding-system +@cindex keyboard input decoding on X This variable specifies the coding system to use for decoding system -error messages, for encoding the format argument to -@code{format-time-string}, and for decoding the return value of -@code{format-time-string}. +error messages and---on X Window system only---keyboard input, for +encoding the format argument to @code{format-time-string}, and for +decoding the return value of @code{format-time-string}. @end defvar @defvar system-messages-locale -@tindex system-messages-locale This variable specifies the locale to use for generating system error messages. Changing the locale can cause messages to come out in a -different language or in a different orthorgraphy. If the variable is +different language or in a different orthography. If the variable is @code{nil}, the locale is specified by environment variables in the usual POSIX fashion. @end defvar @defvar system-time-locale -@tindex system-time-locale This variable specifies the locale to use for formatting time values. Changing the locale can cause messages to appear according to the conventions of a different language. If the variable is @code{nil}, the locale is specified by environment variables in the usual POSIX fashion. @end defvar + +@defun locale-info item +This function returns locale data @var{item} for the current POSIX +locale, if available. @var{item} should be one of these symbols: + +@table @code +@item codeset +Return the character set as a string (locale item @code{CODESET}). + +@item days +Return a 7-element vector of day names (locale items +@code{DAY_1} through @code{DAY_7}); + +@item months +Return a 12-element vector of month names (locale items @code{MON_1} +through @code{MON_12}). + +@item paper +Return a list @code{(@var{width} @var{height})} for the default paper +size measured in millimeters (locale items @code{PAPER_WIDTH} and +@code{PAPER_HEIGHT}). +@end table + +If the system can't provide the requested information, or if +@var{item} is not one of those symbols, the value is @code{nil}. All +strings in the return value are decoded using +@code{locale-coding-system}. @xref{Locales,,, libc, The GNU Libc Manual}, +for more information about locales and locale items. +@end defun + +@ignore + arch-tag: be705bf8-941b-4c35-84fc-ad7d20ddb7cb +@end ignore