1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1997, 1999, 2000, 2001, 2005 Free Software Foundation, Inc.
3 @c See file emacs.texi for copying conditions.
4 @node International, Major Modes, Frames, Top
5 @chapter International Character Set Support
7 @cindex international scripts
8 @cindex multibyte characters
9 @cindex encoding of characters
37 Emacs supports a wide variety of international character sets,
38 including European and Vietnamese variants of the Latin alphabet, as
39 well as Cyrillic, Devanagari (for Hindi and Marathi), Ethiopic, Greek,
40 Han (for Chinese and Japanese), Hangul (for Korean), Hebrew, IPA,
41 Kannada, Lao, Malayalam, Tamil, Thai, Tibetan, and Vietnamese scripts.
42 These features have been merged from the modified version of Emacs
43 known as MULE (for ``MULti-lingual Enhancement to GNU Emacs'')
45 Emacs also supports various encodings of these characters used by
46 other internationalized software, such as word processors and mailers.
48 Emacs allows editing text with international characters by supporting
49 all the related activities:
53 You can visit files with non-@acronym{ASCII} characters, save non-@acronym{ASCII} text, and
54 pass non-@acronym{ASCII} text between Emacs and programs it invokes (such as
55 compilers, spell-checkers, and mailers). Setting your language
56 environment (@pxref{Language Environments}) takes care of setting up the
57 coding systems and other options for a specific language or culture.
58 Alternatively, you can specify how Emacs should encode or decode text
59 for each command; see @ref{Specify Coding}.
62 You can display non-@acronym{ASCII} characters encoded by the various scripts.
63 This works by using appropriate fonts on X and similar graphics
64 displays (@pxref{Defining Fontsets}), and by sending special codes to
65 text-only displays (@pxref{Specify Coding}). If some characters are
66 displayed incorrectly, refer to @ref{Undisplayable Characters}, which
67 describes possible problems and explains how to solve them.
70 You can insert non-@acronym{ASCII} characters or search for them. To do that,
71 you can specify an input method (@pxref{Select Input Method}) suitable
72 for your language, or use the default input method set up when you set
73 your language environment. If
74 your keyboard can produce non-@acronym{ASCII} characters, you can select an
75 appropriate keyboard coding system (@pxref{Specify Coding}), and Emacs
76 will accept those characters. Latin-1 characters can also be input by
77 using the @kbd{C-x 8} prefix, see @ref{Single-Byte Character Support,
78 C-x 8}. On X Window systems, your locale should be set to an
79 appropriate value to make sure Emacs interprets keyboard input
80 correctly; see @ref{Language Environments, locales}.
83 The rest of this chapter describes these issues in detail.
86 * International Chars:: Basic concepts of multibyte characters.
87 * Enabling Multibyte:: Controlling whether to use multibyte characters.
88 * Language Environments:: Setting things up for the language you use.
89 * Input Methods:: Entering text characters not on your keyboard.
90 * Select Input Method:: Specifying your choice of input methods.
91 * Multibyte Conversion:: How single-byte characters convert to multibyte.
92 * Coding Systems:: Character set conversion when you read and
93 write files, and so on.
94 * Recognize Coding:: How Emacs figures out which conversion to use.
95 * Specify Coding:: Various ways to choose which conversion to use.
96 * Fontsets:: Fontsets are collections of fonts
97 that cover the whole spectrum of characters.
98 * Defining Fontsets:: Defining a new fontset.
99 * Undisplayable Characters:: When characters don't display.
100 * Single-Byte Character Support:: You can pick one European character set
101 to use without multibyte characters.
102 * Charsets:: How Emacs groups its internal character codes.
105 @node International Chars
106 @section Introduction to International Character Sets
108 The users of international character sets and scripts have established
109 many more-or-less standard coding systems for storing files. Emacs
110 internally uses a single multibyte character encoding, so that it can
111 intermix characters from all these scripts in a single buffer or string.
112 This encoding represents each non-@acronym{ASCII} character as a sequence of bytes
113 in the range 0200 through 0377. Emacs translates between the multibyte
114 character encoding and various other coding systems when reading and
115 writing files, when exchanging data with subprocesses, and (in some
116 cases) in the @kbd{C-q} command (@pxref{Multibyte Conversion}).
119 @findex view-hello-file
120 @cindex undisplayable characters
121 @cindex @samp{?} in display
122 The command @kbd{C-h h} (@code{view-hello-file}) displays the file
123 @file{etc/HELLO}, which shows how to say ``hello'' in many languages.
124 This illustrates various scripts. If some characters can't be
125 displayed on your terminal, they appear as @samp{?} or as hollow boxes
126 (@pxref{Undisplayable Characters}).
128 Keyboards, even in the countries where these character sets are used,
129 generally don't have keys for all the characters in them. So Emacs
130 supports various @dfn{input methods}, typically one for each script or
131 language, to make it convenient to type them.
134 The prefix key @kbd{C-x @key{RET}} is used for commands that pertain
135 to multibyte characters, coding systems, and input methods.
137 @node Enabling Multibyte
138 @section Enabling Multibyte Characters
140 @cindex turn multibyte support on or off
141 You can enable or disable multibyte character support, either for
142 Emacs as a whole, or for a single buffer. When multibyte characters are
143 disabled in a buffer, then each byte in that buffer represents a
144 character, even codes 0200 through 0377. The old features for
145 supporting the European character sets, ISO Latin-1 and ISO Latin-2,
146 work as they did in Emacs 19 and also work for the other ISO 8859
149 However, there is no need to turn off multibyte character support to
150 use ISO Latin; the Emacs multibyte character set includes all the
151 characters in these character sets, and Emacs can translate
152 automatically to and from the ISO codes.
154 By default, Emacs starts in multibyte mode, because that allows you to
155 use all the supported languages and scripts without limitations.
157 To edit a particular file in unibyte representation, visit it using
158 @code{find-file-literally}. @xref{Visiting}. To convert a buffer in
159 multibyte representation into a single-byte representation of the same
160 characters, the easiest way is to save the contents in a file, kill the
161 buffer, and find the file again with @code{find-file-literally}. You
162 can also use @kbd{C-x @key{RET} c}
163 (@code{universal-coding-system-argument}) and specify @samp{raw-text} as
164 the coding system with which to find or save a file. @xref{Specify
165 Coding}. Finding a file as @samp{raw-text} doesn't disable format
166 conversion, uncompression and auto mode selection as
167 @code{find-file-literally} does.
169 @vindex enable-multibyte-characters
170 @vindex default-enable-multibyte-characters
171 To turn off multibyte character support by default, start Emacs with
172 the @samp{--unibyte} option (@pxref{Initial Options}), or set the
173 environment variable @env{EMACS_UNIBYTE}. You can also customize
174 @code{enable-multibyte-characters} or, equivalently, directly set the
175 variable @code{default-enable-multibyte-characters} to @code{nil} in
176 your init file to have basically the same effect as @samp{--unibyte}.
178 @findex toggle-enable-multibyte-characters
179 To convert a unibyte session to a multibyte session, set
180 @code{default-enable-multibyte-characters} to @code{t}. Buffers which
181 were created in the unibyte session before you turn on multibyte support
182 will stay unibyte. You can turn on multibyte support in a specific
183 buffer by invoking the command @code{toggle-enable-multibyte-characters}
186 @cindex Lisp files, and multibyte operation
187 @cindex multibyte operation, and Lisp files
188 @cindex unibyte operation, and Lisp files
189 @cindex init file, and non-@acronym{ASCII} characters
190 @cindex environment variables, and non-@acronym{ASCII} characters
191 With @samp{--unibyte}, multibyte strings are not created during
192 initialization from the values of environment variables,
193 @file{/etc/passwd} entries etc.@: that contain non-@acronym{ASCII} 8-bit
196 Emacs normally loads Lisp files as multibyte, regardless of whether
197 you used @samp{--unibyte}. This includes the Emacs initialization file,
198 @file{.emacs}, and the initialization files of Emacs packages such as
199 Gnus. However, you can specify unibyte loading for a particular Lisp
200 file, by putting @w{@samp{-*-unibyte: t;-*-}} in a comment on the first
201 line (@pxref{File Variables}). Then that file is always loaded as
202 unibyte text, even if you did not start Emacs with @samp{--unibyte}.
203 The motivation for these conventions is that it is more reliable to
204 always load any particular Lisp file in the same way. However, you can
205 load a Lisp file as unibyte, on any one occasion, by typing @kbd{C-x
206 @key{RET} c raw-text @key{RET}} immediately before loading it.
208 The mode line indicates whether multibyte character support is enabled
209 in the current buffer. If it is, there are two or more characters (most
210 often two dashes) before the colon near the beginning of the mode line.
211 When multibyte characters are not enabled, just one dash precedes the
214 @node Language Environments
215 @section Language Environments
216 @cindex language environments
218 All supported character sets are supported in Emacs buffers whenever
219 multibyte characters are enabled; there is no need to select a
220 particular language in order to display its characters in an Emacs
221 buffer. However, it is important to select a @dfn{language environment}
222 in order to set various defaults. The language environment really
223 represents a choice of preferred script (more or less) rather than a
226 The language environment controls which coding systems to recognize
227 when reading text (@pxref{Recognize Coding}). This applies to files,
228 incoming mail, netnews, and any other text you read into Emacs. It may
229 also specify the default coding system to use when you create a file.
230 Each language environment also specifies a default input method.
232 @findex set-language-environment
233 @vindex current-language-environment
234 To select a language environment, you can customize the variable
235 @code{current-language-environment} or use the command @kbd{M-x
236 set-language-environment}. It makes no difference which buffer is
237 current when you use this command, because the effects apply globally to
238 the Emacs session. The supported language environments include:
243 Belarusian, Brazilian Portuguese, Bulgarian, Chinese-BIG5,
244 Chinese-CNS, Chinese-EUC-TW, Chinese-GB, Croatian, Cyrillic-ALT,
245 Cyrillic-ISO, Cyrillic-KOI8, Czech, Devanagari, Dutch, English,
246 Ethiopic, French, Georgian, German, Greek, Hebrew, IPA, Italian,
247 Japanese, Kannada, Korean, Lao, Latin-1, Latin-2, Latin-3,
248 Latin-4, Latin-5, Latin-6, Latin-7, Latin-8 (Celtic),
249 Latin-9 (updated Latin-1 with the Euro sign), Latvian,
250 Lithuanian, Malayalam, Polish, Romanian, Russian, Slovak,
251 Slovenian, Spanish, Swedish, Tajik, Tamil, Thai, Tibetan,
252 Turkish, UTF-8 (for a setup which prefers Unicode characters and
253 files encoded in UTF-8), Ukrainian, Vietnamese, Welsh, and
254 Windows-1255 (for a setup which prefers Cyrillic characters and
255 files encoded in Windows-1255).
258 @cindex fonts for various scripts
259 @cindex Intlfonts package, installation
260 To display the script(s) used by your language environment on a
261 graphical display, you need to have a suitable font. If some of the
262 characters appear as empty boxes, you should install the GNU Intlfonts
263 package, which includes fonts for most supported scripts.@footnote{If
264 you run Emacs on X, you need to inform the X server about the location
265 of the newly installed fonts with the following commands:
268 xset fp+ /usr/local/share/emacs/fonts
272 @xref{Fontsets}, for more details about setting up your fonts.
274 @findex set-locale-environment
275 @vindex locale-language-names
276 @vindex locale-charset-language-names
278 Some operating systems let you specify the character-set locale you
279 are using by setting the locale environment variables @env{LC_ALL},
280 @env{LC_CTYPE}, or @env{LANG}.@footnote{If more than one of these is
281 set, the first one that is nonempty specifies your locale for this
282 purpose.} During startup, Emacs looks up your character-set locale's
283 name in the system locale alias table, matches its canonical name
284 against entries in the value of the variables
285 @code{locale-charset-language-names} and @code{locale-language-names},
286 and selects the corresponding language environment if a match is found.
287 (The former variable overrides the latter.) It also adjusts the display
288 table and terminal coding system, the locale coding system, the
289 preferred coding system as needed for the locale, and---last but not
290 least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard.
292 If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG}
293 environment variables while running Emacs, you may want to invoke the
294 @code{set-locale-environment} function afterwards to readjust the
295 language environment from the new locale.
297 @vindex locale-preferred-coding-systems
298 The @code{set-locale-environment} function normally uses the preferred
299 coding system established by the language environment to decode system
300 messages. But if your locale matches an entry in the variable
301 @code{locale-preferred-coding-systems}, Emacs uses the corresponding
302 coding system instead. For example, if the locale @samp{ja_JP.PCK}
303 matches @code{japanese-shift-jis} in
304 @code{locale-preferred-coding-systems}, Emacs uses that encoding even
305 though it might normally use @code{japanese-iso-8bit}.
307 You can override the language environment chosen at startup with
308 explicit use of the command @code{set-language-environment}, or with
309 customization of @code{current-language-environment} in your init
313 @findex describe-language-environment
314 To display information about the effects of a certain language
315 environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env}
316 @key{RET}} (@code{describe-language-environment}). This tells you which
317 languages this language environment is useful for, and lists the
318 character sets, coding systems, and input methods that go with it. It
319 also shows some sample text to illustrate scripts used in this language
320 environment. By default, this command describes the chosen language
323 @vindex set-language-environment-hook
324 You can customize any language environment with the normal hook
325 @code{set-language-environment-hook}. The command
326 @code{set-language-environment} runs that hook after setting up the new
327 language environment. The hook functions can test for a specific
328 language environment by checking the variable
329 @code{current-language-environment}. This hook is where you should
330 put non-default settings for specific language environment, such as
331 coding systems for keyboard input and terminal output, the default
334 @vindex exit-language-environment-hook
335 Before it starts to set up the new language environment,
336 @code{set-language-environment} first runs the hook
337 @code{exit-language-environment-hook}. This hook is useful for undoing
338 customizations that were made with @code{set-language-environment-hook}.
339 For instance, if you set up a special key binding in a specific language
340 environment using @code{set-language-environment-hook}, you should set
341 up @code{exit-language-environment-hook} to restore the normal binding
345 @section Input Methods
347 @cindex input methods
348 An @dfn{input method} is a kind of character conversion designed
349 specifically for interactive input. In Emacs, typically each language
350 has its own input method; sometimes several languages which use the same
351 characters can share one input method. A few languages support several
354 The simplest kind of input method works by mapping @acronym{ASCII} letters
355 into another alphabet; this allows you to use one other alphabet
356 instead of @acronym{ASCII}. The Greek and Russian input methods
359 A more powerful technique is composition: converting sequences of
360 characters into one letter. Many European input methods use composition
361 to produce a single non-@acronym{ASCII} letter from a sequence that consists of a
362 letter followed by accent characters (or vice versa). For example, some
363 methods convert the sequence @kbd{a'} into a single accented letter.
364 These input methods have no special commands of their own; all they do
365 is compose sequences of printing characters.
367 The input methods for syllabic scripts typically use mapping followed
368 by composition. The input methods for Thai and Korean work this way.
369 First, letters are mapped into symbols for particular sounds or tone
370 marks; then, sequences of these which make up a whole syllable are
371 mapped into one syllable sign.
373 Chinese and Japanese require more complex methods. In Chinese input
374 methods, first you enter the phonetic spelling of a Chinese word (in
375 input method @code{chinese-py}, among others), or a sequence of
376 portions of the character (input methods @code{chinese-4corner} and
377 @code{chinese-sw}, and others). One input sequence typically
378 corresponds to many possible Chinese characters. You select the one
379 you mean using keys such as @kbd{C-f}, @kbd{C-b}, @kbd{C-n},
380 @kbd{C-p}, and digits, which have special meanings in this situation.
382 The possible characters are conceptually arranged in several rows,
383 with each row holding up to 10 alternatives. Normally, Emacs displays
384 just one row at a time, in the echo area; @code{(@var{i}/@var{j})}
385 appears at the beginning, to indicate that this is the @var{i}th row
386 out of a total of @var{j} rows. Type @kbd{C-n} or @kbd{C-p} to
387 display the next row or the previous row.
389 Type @kbd{C-f} and @kbd{C-b} to move forward and backward among
390 the alternatives in the current row. As you do this, Emacs highlights
391 the current alternative with a special color; type @code{C-@key{SPC}}
392 to select the current alternative and use it as input. The
393 alternatives in the row are also numbered; the number appears before
394 the alternative. Typing a digit @var{n} selects the @var{n}th
395 alternative of the current row and uses it as input.
397 @key{TAB} in these Chinese input methods displays a buffer showing
398 all the possible characters at once; then clicking @kbd{Mouse-2} on
399 one of them selects that alternative. The keys @kbd{C-f}, @kbd{C-b},
400 @kbd{C-n}, @kbd{C-p}, and digits continue to work as usual, but they
401 do the highlighting in the buffer showing the possible characters,
402 rather than in the echo area.
404 In Japanese input methods, first you input a whole word using
405 phonetic spelling; then, after the word is in the buffer, Emacs
406 converts it into one or more characters using a large dictionary. One
407 phonetic spelling corresponds to a number of different Japanese words;
408 to select one of them, use @kbd{C-n} and @kbd{C-p} to cycle through
411 Sometimes it is useful to cut off input method processing so that the
412 characters you have just entered will not combine with subsequent
413 characters. For example, in input method @code{latin-1-postfix}, the
414 sequence @kbd{e '} combines to form an @samp{e} with an accent. What if
415 you want to enter them as separate characters?
417 One way is to type the accent twice; this is a special feature for
418 entering the separate letter and accent. For example, @kbd{e ' '} gives
419 you the two characters @samp{e'}. Another way is to type another letter
420 after the @kbd{e}---something that won't combine with that---and
421 immediately delete it. For example, you could type @kbd{e e @key{DEL}
422 '} to get separate @samp{e} and @samp{'}.
424 Another method, more general but not quite as easy to type, is to use
425 @kbd{C-\ C-\} between two characters to stop them from combining. This
426 is the command @kbd{C-\} (@code{toggle-input-method}) used twice.
428 @xref{Select Input Method}.
431 @cindex incremental search, input method interference
432 @kbd{C-\ C-\} is especially useful inside an incremental search,
433 because it stops waiting for more characters to combine, and starts
434 searching for what you have already entered.
436 To find out how to input the character after point using the current
437 input method, type @kbd{C-u C-x =}. @xref{Position Info}.
439 @vindex input-method-verbose-flag
440 @vindex input-method-highlight-flag
441 The variables @code{input-method-highlight-flag} and
442 @code{input-method-verbose-flag} control how input methods explain
443 what is happening. If @code{input-method-highlight-flag} is
444 non-@code{nil}, the partial sequence is highlighted in the buffer (for
445 most input methods---some disable this feature). If
446 @code{input-method-verbose-flag} is non-@code{nil}, the list of
447 possible characters to type next is displayed in the echo area (but
448 not when you are in the minibuffer).
450 @node Select Input Method
451 @section Selecting an Input Method
455 Enable or disable use of the selected input method.
457 @item C-x @key{RET} C-\ @var{method} @key{RET}
458 Select a new input method for the current buffer.
460 @item C-h I @var{method} @key{RET}
461 @itemx C-h C-\ @var{method} @key{RET}
462 @findex describe-input-method
465 Describe the input method @var{method} (@code{describe-input-method}).
466 By default, it describes the current input method (if any). This
467 description should give you the full details of how to use any
468 particular input method.
470 @item M-x list-input-methods
471 Display a list of all the supported input methods.
474 @findex set-input-method
475 @vindex current-input-method
477 To choose an input method for the current buffer, use @kbd{C-x
478 @key{RET} C-\} (@code{set-input-method}). This command reads the
479 input method name from the minibuffer; the name normally starts with the
480 language environment that it is meant to be used with. The variable
481 @code{current-input-method} records which input method is selected.
483 @findex toggle-input-method
485 Input methods use various sequences of @acronym{ASCII} characters to stand for
486 non-@acronym{ASCII} characters. Sometimes it is useful to turn off the input
487 method temporarily. To do this, type @kbd{C-\}
488 (@code{toggle-input-method}). To reenable the input method, type
491 If you type @kbd{C-\} and you have not yet selected an input method,
492 it prompts for you to specify one. This has the same effect as using
493 @kbd{C-x @key{RET} C-\} to specify an input method.
495 When invoked with a numeric argument, as in @kbd{C-u C-\},
496 @code{toggle-input-method} always prompts you for an input method,
497 suggesting the most recently selected one as the default.
499 @vindex default-input-method
500 Selecting a language environment specifies a default input method for
501 use in various buffers. When you have a default input method, you can
502 select it in the current buffer by typing @kbd{C-\}. The variable
503 @code{default-input-method} specifies the default input method
504 (@code{nil} means there is none).
506 In some language environments, which support several different input
507 methods, you might want to use an input method different from the
508 default chosen by @code{set-language-environment}. You can instruct
509 Emacs to select a different default input method for a certain
510 language environment, if you wish, by using
511 @code{set-language-environment-hook} (@pxref{Language Environments,
512 set-language-environment-hook}). For example:
515 (defun my-chinese-setup ()
516 "Set up my private Chinese environment."
517 (if (equal current-language-environment "Chinese-GB")
518 (setq default-input-method "chinese-tonepy")))
519 (add-hook 'set-language-environment-hook 'my-chinese-setup)
523 This sets the default input method to be @code{chinese-tonepy}
524 whenever you choose a Chinese-GB language environment.
526 @findex quail-set-keyboard-layout
527 Some input methods for alphabetic scripts work by (in effect)
528 remapping the keyboard to emulate various keyboard layouts commonly used
529 for those scripts. How to do this remapping properly depends on your
530 actual keyboard layout. To specify which layout your keyboard has, use
531 the command @kbd{M-x quail-set-keyboard-layout}.
533 @findex quail-show-key
534 You can use the command @kbd{M-x quail-show-key} to show what key (or
535 key sequence) to type in order to input the character following point,
536 using the selected keyboard layout. The command @kbd{C-u C-x =} also
537 shows that information in addition to the other information about the
540 @findex list-input-methods
541 To display a list of all the supported input methods, type @kbd{M-x
542 list-input-methods}. The list gives information about each input
543 method, including the string that stands for it in the mode line.
545 @node Multibyte Conversion
546 @section Unibyte and Multibyte Non-@acronym{ASCII} characters
548 When multibyte characters are enabled, character codes 0240 (octal)
549 through 0377 (octal) are not really legitimate in the buffer. The valid
550 non-@acronym{ASCII} printing characters have codes that start from 0400.
552 If you type a self-inserting character in the range 0240 through
553 0377, or if you use @kbd{C-q} to insert one, Emacs assumes you
554 intended to use one of the ISO Latin-@var{n} character sets, and
555 converts it to the Emacs code representing that Latin-@var{n}
556 character. You select @emph{which} ISO Latin character set to use
557 through your choice of language environment
562 (@pxref{Language Environments}).
564 If you do not specify a choice, the default is Latin-1.
566 If you insert a character in the range 0200 through 0237, which
567 forms the @code{eight-bit-control} character set, it is inserted
568 literally. You should normally avoid doing this since buffers
569 containing such characters have to be written out in either the
570 @code{emacs-mule} or @code{raw-text} coding system, which is usually
574 @section Coding Systems
575 @cindex coding systems
577 Users of various languages have established many more-or-less standard
578 coding systems for representing them. Emacs does not use these coding
579 systems internally; instead, it converts from various coding systems to
580 its own system when reading data, and converts the internal coding
581 system to other coding systems when writing data. Conversion is
582 possible in reading or writing files, in sending or receiving from the
583 terminal, and in exchanging data with subprocesses.
585 Emacs assigns a name to each coding system. Most coding systems are
586 used for one language, and the name of the coding system starts with the
587 language name. Some coding systems are used for several languages;
588 their names usually start with @samp{iso}. There are also special
589 coding systems @code{no-conversion}, @code{raw-text} and
590 @code{emacs-mule} which do not convert printing characters at all.
592 @cindex international files from DOS/Windows systems
593 A special class of coding systems, collectively known as
594 @dfn{codepages}, is designed to support text encoded by MS-Windows and
595 MS-DOS software. To use any of these systems, you need to create it
596 with @kbd{M-x codepage-setup}. @xref{MS-DOS and MULE}. After
597 creating the coding system for the codepage, you can use it as any
598 other coding system. For example, to visit a file encoded in codepage
599 850, type @kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename}
602 In addition to converting various representations of non-@acronym{ASCII}
603 characters, a coding system can perform end-of-line conversion. Emacs
604 handles three different conventions for how to separate lines in a file:
605 newline, carriage-return linefeed, and just carriage-return.
608 @item C-h C @var{coding} @key{RET}
609 Describe coding system @var{coding}.
611 @item C-h C @key{RET}
612 Describe the coding systems currently in use.
614 @item M-x list-coding-systems
615 Display a list of all the supported coding systems.
619 @findex describe-coding-system
620 The command @kbd{C-h C} (@code{describe-coding-system}) displays
621 information about particular coding systems. You can specify a coding
622 system name as the argument; alternatively, with an empty argument, it
623 describes the coding systems currently selected for various purposes,
624 both in the current buffer and as the defaults, and the priority list
625 for recognizing coding systems (@pxref{Recognize Coding}).
627 @findex list-coding-systems
628 To display a list of all the supported coding systems, type @kbd{M-x
629 list-coding-systems}. The list gives information about each coding
630 system, including the letter that stands for it in the mode line
633 @cindex end-of-line conversion
634 @cindex MS-DOS end-of-line conversion
635 @cindex Macintosh end-of-line conversion
636 Each of the coding systems that appear in this list---except for
637 @code{no-conversion}, which means no conversion of any kind---specifies
638 how and whether to convert printing characters, but leaves the choice of
639 end-of-line conversion to be decided based on the contents of each file.
640 For example, if the file appears to use the sequence carriage-return
641 linefeed to separate lines, DOS end-of-line conversion will be used.
643 Each of the listed coding systems has three variants which specify
644 exactly what to do for end-of-line conversion:
648 Don't do any end-of-line conversion; assume the file uses
649 newline to separate lines. (This is the convention normally used
650 on Unix and GNU systems.)
653 Assume the file uses carriage-return linefeed to separate lines, and do
654 the appropriate conversion. (This is the convention normally used on
655 Microsoft systems.@footnote{It is also specified for MIME @samp{text/*}
656 bodies and in other network transport contexts. It is different
657 from the SGML reference syntax record-start/record-end format which
658 Emacs doesn't support directly.})
661 Assume the file uses carriage-return to separate lines, and do the
662 appropriate conversion. (This is the convention normally used on the
666 These variant coding systems are omitted from the
667 @code{list-coding-systems} display for brevity, since they are entirely
668 predictable. For example, the coding system @code{iso-latin-1} has
669 variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and
670 @code{iso-latin-1-mac}.
672 The coding system @code{raw-text} is good for a file which is mainly
673 @acronym{ASCII} text, but may contain byte values above 127 which are not meant to
674 encode non-@acronym{ASCII} characters. With @code{raw-text}, Emacs copies those
675 byte values unchanged, and sets @code{enable-multibyte-characters} to
676 @code{nil} in the current buffer so that they will be interpreted
677 properly. @code{raw-text} handles end-of-line conversion in the usual
678 way, based on the data encountered, and has the usual three variants to
679 specify the kind of end-of-line conversion to use.
681 In contrast, the coding system @code{no-conversion} specifies no
682 character code conversion at all---none for non-@acronym{ASCII} byte values and
683 none for end of line. This is useful for reading or writing binary
684 files, tar files, and other files that must be examined verbatim. It,
685 too, sets @code{enable-multibyte-characters} to @code{nil}.
687 The easiest way to edit a file with no conversion of any kind is with
688 the @kbd{M-x find-file-literally} command. This uses
689 @code{no-conversion}, and also suppresses other Emacs features that
690 might convert the file contents before you see them. @xref{Visiting}.
692 The coding system @code{emacs-mule} means that the file contains
693 non-@acronym{ASCII} characters stored with the internal Emacs encoding. It
694 handles end-of-line conversion based on the data encountered, and has
695 the usual three variants to specify the kind of end-of-line conversion.
697 @node Recognize Coding
698 @section Recognizing Coding Systems
700 Emacs tries to recognize which coding system to use for a given text
701 as an integral part of reading that text. (This applies to files
702 being read, output from subprocesses, text from X selections, etc.)
703 Emacs can select the right coding system automatically most of the
704 time---once you have specified your preferences.
706 Some coding systems can be recognized or distinguished by which byte
707 sequences appear in the data. However, there are coding systems that
708 cannot be distinguished, not even potentially. For example, there is no
709 way to distinguish between Latin-1 and Latin-2; they use the same byte
710 values with different meanings.
712 Emacs handles this situation by means of a priority list of coding
713 systems. Whenever Emacs reads a file, if you do not specify the coding
714 system to use, Emacs checks the data against each coding system,
715 starting with the first in priority and working down the list, until it
716 finds a coding system that fits the data. Then it converts the file
717 contents assuming that they are represented in this coding system.
719 The priority list of coding systems depends on the selected language
720 environment (@pxref{Language Environments}). For example, if you use
721 French, you probably want Emacs to prefer Latin-1 to Latin-2; if you use
722 Czech, you probably want Latin-2 to be preferred. This is one of the
723 reasons to specify a language environment.
725 @findex prefer-coding-system
726 However, you can alter the coding system priority list in detail
727 with the command @kbd{M-x prefer-coding-system}. This command reads
728 the name of a coding system from the minibuffer, and adds it to the
729 front of the priority list, so that it is preferred to all others. If
730 you use this command several times, each use adds one element to the
731 front of the priority list.
733 If you use a coding system that specifies the end-of-line conversion
734 type, such as @code{iso-8859-1-dos}, what this means is that Emacs
735 should attempt to recognize @code{iso-8859-1} with priority, and should
736 use DOS end-of-line conversion when it does recognize @code{iso-8859-1}.
738 @vindex file-coding-system-alist
739 Sometimes a file name indicates which coding system to use for the
740 file. The variable @code{file-coding-system-alist} specifies this
741 correspondence. There is a special function
742 @code{modify-coding-system-alist} for adding elements to this list. For
743 example, to read and write all @samp{.txt} files using the coding system
744 @code{china-iso-8bit}, you can execute this Lisp expression:
747 (modify-coding-system-alist 'file "\\.txt\\'" 'chinese-iso-8bit)
751 The first argument should be @code{file}, the second argument should be
752 a regular expression that determines which files this applies to, and
753 the third argument says which coding system to use for these files.
755 @vindex inhibit-eol-conversion
756 @cindex DOS-style end-of-line display
757 Emacs recognizes which kind of end-of-line conversion to use based on
758 the contents of the file: if it sees only carriage-returns, or only
759 carriage-return linefeed sequences, then it chooses the end-of-line
760 conversion accordingly. You can inhibit the automatic use of
761 end-of-line conversion by setting the variable @code{inhibit-eol-conversion}
762 to non-@code{nil}. If you do that, DOS-style files will be displayed
763 with the @samp{^M} characters visible in the buffer; some people
764 prefer this to the more subtle @samp{(DOS)} end-of-line type
765 indication near the left edge of the mode line (@pxref{Mode Line,
768 @vindex inhibit-iso-escape-detection
769 @cindex escape sequences in files
770 By default, the automatic detection of coding system is sensitive to
771 escape sequences. If Emacs sees a sequence of characters that begin
772 with an escape character, and the sequence is valid as an ISO-2022
773 code, that tells Emacs to use one of the ISO-2022 encodings to decode
776 However, there may be cases that you want to read escape sequences
777 in a file as is. In such a case, you can set the variable
778 @code{inhibit-iso-escape-detection} to non-@code{nil}. Then the code
779 detection ignores any escape sequences, and never uses an ISO-2022
780 encoding. The result is that all escape sequences become visible in
783 The default value of @code{inhibit-iso-escape-detection} is
784 @code{nil}. We recommend that you not change it permanently, only for
785 one specific operation. That's because many Emacs Lisp source files
786 in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the
787 coding system @code{iso-2022-7bit}, and they won't be
788 decoded correctly when you visit those files if you suppress the
789 escape sequence detection.
792 You can specify the coding system for a particular file using the
793 @w{@samp{-*-@dots{}-*-}} construct at the beginning of a file, or a
794 local variables list at the end (@pxref{File Variables}). You do this
795 by defining a value for the ``variable'' named @code{coding}. Emacs
796 does not really have a variable @code{coding}; instead of setting a
797 variable, this uses the specified coding system for the file. For
798 example, @samp{-*-mode: C; coding: latin-1;-*-} specifies use of the
799 Latin-1 coding system, as well as C mode. When you specify the coding
800 explicitly in the file, that overrides
801 @code{file-coding-system-alist}.
803 @vindex auto-coding-alist
804 @vindex auto-coding-regexp-alist
805 @vindex auto-coding-functions
806 The variables @code{auto-coding-alist},
807 @code{auto-coding-regexp-alist} and @code{auto-coding-functions} are
808 the strongest way to specify the coding system for certain patterns of
809 file names, or for files containing certain patterns; these variables
810 even override @samp{-*-coding:-*-} tags in the file itself. Emacs
811 uses @code{auto-coding-alist} for tar and archive files, to prevent it
812 from being confused by a @samp{-*-coding:-*-} tag in a member of the
813 archive and thinking it applies to the archive file as a whole.
814 Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that
815 RMAIL files, whose names in general don't match any particular
816 pattern, are decoded correctly. One of the builtin
817 @code{auto-coding-functions} detects the encoding for XML files.
819 If Emacs recognizes the encoding of a file incorrectly, you can
820 reread the file using the correct coding system by typing @kbd{C-x
821 @key{RET} r @var{coding-system}
822 @key{RET}}. To see what coding system Emacs actually used to decode
823 the file, look at the coding system mnemonic letter near the left edge
824 of the mode line (@pxref{Mode Line}), or type @kbd{C-h C @key{RET}}.
826 @findex unify-8859-on-decoding-mode
827 The command @code{unify-8859-on-decoding-mode} enables a mode that
828 ``unifies'' the Latin alphabets when decoding text. This works by
829 converting all non-@acronym{ASCII} Latin-@var{n} characters to either Latin-1 or
830 Unicode characters. This way it is easier to use various
831 Latin-@var{n} alphabets together. In a future Emacs version we hope
832 to move towards full Unicode support and complete unification of
835 @vindex buffer-file-coding-system
836 Once Emacs has chosen a coding system for a buffer, it stores that
837 coding system in @code{buffer-file-coding-system} and uses that coding
838 system, by default, for operations that write from this buffer into a
839 file. This includes the commands @code{save-buffer} and
840 @code{write-region}. If you want to write files from this buffer using
841 a different coding system, you can specify a different coding system for
842 the buffer using @code{set-buffer-file-coding-system} (@pxref{Specify
845 You can insert any possible character into any Emacs buffer, but
846 most coding systems can only handle some of the possible characters.
847 This means that it is possible for you to insert characters that
848 cannot be encoded with the coding system that will be used to save the
849 buffer. For example, you could start with an @acronym{ASCII} file and insert a
850 few Latin-1 characters into it, or you could edit a text file in
851 Polish encoded in @code{iso-8859-2} and add some Russian words to it.
852 When you save the buffer, Emacs cannot use the current value of
853 @code{buffer-file-coding-system}, because the characters you added
854 cannot be encoded by that coding system.
856 When that happens, Emacs tries the most-preferred coding system (set
857 by @kbd{M-x prefer-coding-system} or @kbd{M-x
858 set-language-environment}), and if that coding system can safely
859 encode all of the characters in the buffer, Emacs uses it, and stores
860 its value in @code{buffer-file-coding-system}. Otherwise, Emacs
861 displays a list of coding systems suitable for encoding the buffer's
862 contents, and asks you to choose one of those coding systems.
864 If you insert the unsuitable characters in a mail message, Emacs
865 behaves a bit differently. It additionally checks whether the
866 most-preferred coding system is recommended for use in MIME messages;
867 if not, Emacs tells you that the most-preferred coding system is
868 not recommended and prompts you for another coding system. This is so
869 you won't inadvertently send a message encoded in a way that your
870 recipient's mail software will have difficulty decoding. (If you do
871 want to use the most-preferred coding system, you can still type its
872 name in response to the question.)
874 @vindex sendmail-coding-system
875 When you send a message with Mail mode (@pxref{Sending Mail}), Emacs has
876 four different ways to determine the coding system to use for encoding
877 the message text. It tries the buffer's own value of
878 @code{buffer-file-coding-system}, if that is non-@code{nil}. Otherwise,
879 it uses the value of @code{sendmail-coding-system}, if that is
880 non-@code{nil}. The third way is to use the default coding system for
881 new files, which is controlled by your choice of language environment,
882 if that is non-@code{nil}. If all of these three values are @code{nil},
883 Emacs encodes outgoing mail using the Latin-1 coding system.
885 @vindex rmail-decode-mime-charset
886 When you get new mail in Rmail, each message is translated
887 automatically from the coding system it is written in, as if it were a
888 separate file. This uses the priority list of coding systems that you
889 have specified. If a MIME message specifies a character set, Rmail
890 obeys that specification, unless @code{rmail-decode-mime-charset} is
893 @vindex rmail-file-coding-system
894 For reading and saving Rmail files themselves, Emacs uses the coding
895 system specified by the variable @code{rmail-file-coding-system}. The
896 default value is @code{nil}, which means that Rmail files are not
897 translated (they are read and written in the Emacs internal character
901 @section Specifying a Coding System
903 In cases where Emacs does not automatically choose the right coding
904 system, you can use these commands to specify one:
907 @item C-x @key{RET} f @var{coding} @key{RET}
908 Use coding system @var{coding} for saving or revisiting the visited
909 file in the current buffer.
911 @item C-x @key{RET} c @var{coding} @key{RET}
912 Specify coding system @var{coding} for the immediately following
915 @item C-x @key{RET} r @var{coding} @key{RET}
916 Revisit the current file using the coding system @var{coding}.
918 @item C-x @key{RET} k @var{coding} @key{RET}
919 Use coding system @var{coding} for keyboard input.
921 @item C-x @key{RET} t @var{coding} @key{RET}
922 Use coding system @var{coding} for terminal output.
924 @item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET}
925 Use coding systems @var{input-coding} and @var{output-coding} for
926 subprocess input and output in the current buffer.
928 @item C-x @key{RET} x @var{coding} @key{RET}
929 Use coding system @var{coding} for transferring selections to and from
930 other programs through the window system.
932 @item C-x @key{RET} F @var{coding} @key{RET}
933 Use coding system @var{coding} for encoding and decoding file
934 @emph{names}. This affects the use of non-ASCII characters in file
935 names. It has no effect on reading and writing the @emph{contents} of
938 @item C-x @key{RET} X @var{coding} @key{RET}
939 Use coding system @var{coding} for transferring @emph{one}
940 selection---the next one---to or from the window system.
942 @item M-x recode-region
943 Convert the region from a previous coding system to a new one.
947 @findex set-buffer-file-coding-system
948 The command @kbd{C-x @key{RET} f}
949 (@code{set-buffer-file-coding-system}) sets the file coding system for
950 the current buffer---in other words, it says which coding system to
951 use when saving or reverting the visited file. You specify which
952 coding system using the minibuffer. If you specify a coding system
953 that cannot handle all of the characters in the buffer, Emacs warns
954 you about the troublesome characters when you actually save the
958 @findex universal-coding-system-argument
959 Another way to specify the coding system for a file is when you visit
960 the file. First use the command @kbd{C-x @key{RET} c}
961 (@code{universal-coding-system-argument}); this command uses the
962 minibuffer to read a coding system name. After you exit the minibuffer,
963 the specified coding system is used for @emph{the immediately following
966 So if the immediately following command is @kbd{C-x C-f}, for example,
967 it reads the file using that coding system (and records the coding
968 system for when you later save the file). Or if the immediately following
969 command is @kbd{C-x C-w}, it writes the file using that coding system.
970 When you specify the coding system for saving in this way, instead
971 of with @kbd{C-x @key{RET} f}, there is no warning if the buffer
972 contains characters that the coding system cannot handle.
974 Other file commands affected by a specified coding system include
975 @kbd{C-x C-i} and @kbd{C-x C-v}, as well as the other-window variants
976 of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that
977 start subprocesses, including @kbd{M-x shell} (@pxref{Shell}).
979 If the immediately following command does not use the coding system,
980 then @kbd{C-x @key{RET} c} ultimately has no effect.
982 An easy way to visit a file with no conversion is with the @kbd{M-x
983 find-file-literally} command. @xref{Visiting}.
985 @vindex default-buffer-file-coding-system
986 The variable @code{default-buffer-file-coding-system} specifies the
987 choice of coding system to use when you create a new file. It applies
988 when you find a new file, and when you create a buffer and then save it
989 in a file. Selecting a language environment typically sets this
990 variable to a good choice of default coding system for that language
994 @findex revert-buffer-with-coding-system
995 If you visit a file with a wrong coding system, you can correct this
996 with @kbd{C-x @key{RET} r} (@code{revert-buffer-with-coding-system}).
997 This visits the current file again, using a coding system you specify.
1000 @findex set-terminal-coding-system
1001 The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system})
1002 specifies the coding system for terminal output. If you specify a
1003 character code for terminal output, all characters output to the
1004 terminal are translated into that coding system.
1006 This feature is useful for certain character-only terminals built to
1007 support specific languages or character sets---for example, European
1008 terminals that support one of the ISO Latin character sets. You need to
1009 specify the terminal coding system when using multibyte text, so that
1010 Emacs knows which characters the terminal can actually handle.
1012 By default, output to the terminal is not translated at all, unless
1013 Emacs can deduce the proper coding system from your terminal type or
1014 your locale specification (@pxref{Language Environments}).
1017 @findex set-keyboard-coding-system
1018 @vindex keyboard-coding-system
1019 The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system})
1020 or the variable @code{keyboard-coding-system} specifies the coding
1021 system for keyboard input. Character-code translation of keyboard
1022 input is useful for terminals with keys that send non-@acronym{ASCII}
1023 graphic characters---for example, some terminals designed for ISO
1024 Latin-1 or subsets of it.
1026 By default, keyboard input is translated based on your system locale
1027 setting. If your terminal does not really support the encoding
1028 implied by your locale (for example, if you find it inserts a
1029 non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set
1030 @code{keyboard-coding-system} to @code{nil} to turn off encoding.
1031 You can do this by putting
1034 (set-keyboard-coding-system nil)
1038 in your @file{~/.emacs} file.
1040 There is a similarity between using a coding system translation for
1041 keyboard input, and using an input method: both define sequences of
1042 keyboard input that translate into single characters. However, input
1043 methods are designed to be convenient for interactive use by humans, and
1044 the sequences that are translated are typically sequences of @acronym{ASCII}
1045 printing characters. Coding systems typically translate sequences of
1046 non-graphic characters.
1050 @findex set-selection-coding-system
1051 @findex set-next-selection-coding-system
1052 The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system})
1053 specifies the coding system for sending selected text to the window
1054 system, and for receiving the text of selections made in other
1055 applications. This command applies to all subsequent selections, until
1056 you override it by using the command again. The command @kbd{C-x
1057 @key{RET} X} (@code{set-next-selection-coding-system}) specifies the
1058 coding system for the next selection made in Emacs or read by Emacs.
1061 @findex set-buffer-process-coding-system
1062 The command @kbd{C-x @key{RET} p} (@code{set-buffer-process-coding-system})
1063 specifies the coding system for input and output to a subprocess. This
1064 command applies to the current buffer; normally, each subprocess has its
1065 own buffer, and thus you can use this command to specify translation to
1066 and from a particular subprocess by giving the command in the
1067 corresponding buffer.
1069 The default for translation of process input and output depends on the
1070 current language environment.
1072 @findex recode-region
1073 If a piece of text has already been inserted into a buffer using the
1074 wrong coding system, you can decode it again using @kbd{M-x
1075 recode-region}. This prompts you for the old coding system and the
1076 desired coding system, and acts on the text in the region.
1078 @vindex file-name-coding-system
1079 @cindex file names with non-@acronym{ASCII} characters
1080 @findex set-file-name-coding-system
1081 @kindex C-x @key{RET} F
1082 The variable @code{file-name-coding-system} specifies a coding
1083 system to use for encoding file names. If you set the variable to a
1084 coding system name (as a Lisp symbol or a string), Emacs encodes file
1085 names using that coding system for all file operations. This makes it
1086 possible to use non-@acronym{ASCII} characters in file names---or, at
1087 least, those non-@acronym{ASCII} characters which the specified coding
1088 system can encode. Use @kbd{C-x @key{RET} F}
1089 (@code{set-file-name-coding-system}) to specify this interactively.
1091 If @code{file-name-coding-system} is @code{nil}, Emacs uses a default
1092 coding system determined by the selected language environment. In the
1093 default language environment, any non-@acronym{ASCII} characters in file names are
1094 not encoded specially; they appear in the file system using the internal
1095 Emacs representation.
1097 @strong{Warning:} if you change @code{file-name-coding-system} (or the
1098 language environment) in the middle of an Emacs session, problems can
1099 result if you have already visited files whose names were encoded using
1100 the earlier coding system and cannot be encoded (or are encoded
1101 differently) under the new coding system. If you try to save one of
1102 these buffers under the visited file name, saving may use the wrong file
1103 name, or it may get an error. If such a problem happens, use @kbd{C-x
1104 C-w} to specify a new file name for that buffer.
1106 @findex recode-file-name
1107 If a mistake occurs when encoding a file name, use the command
1108 @kbd{M-x recode-file-name} to change the file name's coding
1109 system. This prompts for an existing file name, its old coding
1110 system, and the coding system to which you wish to convert.
1112 @vindex locale-coding-system
1113 @cindex decoding non-@acronym{ASCII} keyboard input on X
1114 The variable @code{locale-coding-system} specifies a coding system
1115 to use when encoding and decoding system strings such as system error
1116 messages and @code{format-time-string} formats and time stamps. That
1117 coding system is also used for decoding non-@acronym{ASCII} keyboard input on X
1118 Window systems. You should choose a coding system that is compatible
1119 with the underlying system's text representation, which is normally
1120 specified by one of the environment variables @env{LC_ALL},
1121 @env{LC_CTYPE}, and @env{LANG}. (The first one, in the order
1122 specified above, whose value is nonempty is the one that determines
1123 the text representation.)
1129 A font for X typically defines shapes for a single alphabet or script.
1130 Therefore, displaying the entire range of scripts that Emacs supports
1131 requires a collection of many fonts. In Emacs, such a collection is
1132 called a @dfn{fontset}. A fontset is defined by a list of fonts, each
1133 assigned to handle a range of character codes.
1135 Each fontset has a name, like a font. The available X fonts are
1136 defined by the X server; fontsets, however, are defined within Emacs
1137 itself. Once you have defined a fontset, you can use it within Emacs by
1138 specifying its name, anywhere that you could use a single font. Of
1139 course, Emacs fontsets can use only the fonts that the X server
1140 supports; if certain characters appear on the screen as hollow boxes,
1141 this means that the fontset in use for them has no font for those
1142 characters.@footnote{The Emacs installation instructions have information on
1143 additional font support.}
1145 Emacs creates two fontsets automatically: the @dfn{standard fontset}
1146 and the @dfn{startup fontset}. The standard fontset is most likely to
1147 have fonts for a wide variety of non-@acronym{ASCII} characters; however, this is
1148 not the default for Emacs to use. (By default, Emacs tries to find a
1149 font that has bold and italic variants.) You can specify use of the
1150 standard fontset with the @samp{-fn} option, or with the @samp{Font} X
1151 resource (@pxref{Font X}). For example,
1154 emacs -fn fontset-standard
1157 A fontset does not necessarily specify a font for every character
1158 code. If a fontset specifies no font for a certain character, or if it
1159 specifies a font that does not exist on your system, then it cannot
1160 display that character properly. It will display that character as an
1163 @node Defining Fontsets
1164 @section Defining fontsets
1166 @vindex standard-fontset-spec
1167 @cindex standard fontset
1168 Emacs creates a standard fontset automatically according to the value
1169 of @code{standard-fontset-spec}. This fontset's name is
1172 -*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard
1176 or just @samp{fontset-standard} for short.
1178 Bold, italic, and bold-italic variants of the standard fontset are
1179 created automatically. Their names have @samp{bold} instead of
1180 @samp{medium}, or @samp{i} instead of @samp{r}, or both.
1182 @cindex startup fontset
1183 If you specify a default @acronym{ASCII} font with the @samp{Font} resource or
1184 the @samp{-fn} argument, Emacs generates a fontset from it
1185 automatically. This is the @dfn{startup fontset} and its name is
1186 @code{fontset-startup}. It does this by replacing the @var{foundry},
1187 @var{family}, @var{add_style}, and @var{average_width} fields of the
1188 font name with @samp{*}, replacing @var{charset_registry} field with
1189 @samp{fontset}, and replacing @var{charset_encoding} field with
1190 @samp{startup}, then using the resulting string to specify a fontset.
1192 For instance, if you start Emacs this way,
1195 emacs -fn "*courier-medium-r-normal--14-140-*-iso8859-1"
1199 Emacs generates the following fontset and uses it for the initial X
1203 -*-*-medium-r-normal-*-14-140-*-*-*-*-fontset-startup
1206 With the X resource @samp{Emacs.Font}, you can specify a fontset name
1207 just like an actual font name. But be careful not to specify a fontset
1208 name in a wildcard resource like @samp{Emacs*Font}---that wildcard
1209 specification matches various other resources, such as for menus, and
1210 menus cannot handle fontsets.
1212 You can specify additional fontsets using X resources named
1213 @samp{Fontset-@var{n}}, where @var{n} is an integer starting from 0.
1214 The resource value should have this form:
1217 @var{fontpattern}, @r{[}@var{charsetname}:@var{fontname}@r{]@dots{}}
1221 @var{fontpattern} should have the form of a standard X font name, except
1222 for the last two fields. They should have the form
1223 @samp{fontset-@var{alias}}.
1225 The fontset has two names, one long and one short. The long name is
1226 @var{fontpattern}. The short name is @samp{fontset-@var{alias}}. You
1227 can refer to the fontset by either name.
1229 The construct @samp{@var{charset}:@var{font}} specifies which font to
1230 use (in this fontset) for one particular character set. Here,
1231 @var{charset} is the name of a character set, and @var{font} is the
1232 font to use for that character set. You can use this construct any
1233 number of times in defining one fontset.
1235 For the other character sets, Emacs chooses a font based on
1236 @var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values
1237 that describe the character set. For the @acronym{ASCII} character font,
1238 @samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}.
1240 In addition, when several consecutive fields are wildcards, Emacs
1241 collapses them into a single wildcard. This is to prevent use of
1242 auto-scaled fonts. Fonts made by scaling larger fonts are not usable
1243 for editing, and scaling a smaller font is not useful because it is
1244 better to use the smaller font in its own size, which is what Emacs
1247 Thus if @var{fontpattern} is this,
1250 -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24
1254 the font specification for @acronym{ASCII} characters would be this:
1257 -*-fixed-medium-r-normal-*-24-*-ISO8859-1
1261 and the font specification for Chinese GB2312 characters would be this:
1264 -*-fixed-medium-r-normal-*-24-*-gb2312*-*
1267 You may not have any Chinese font matching the above font
1268 specification. Most X distributions include only Chinese fonts that
1269 have @samp{song ti} or @samp{fangsong ti} in @var{family} field. In
1270 such a case, @samp{Fontset-@var{n}} can be specified as below:
1273 Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\
1274 chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-*
1278 Then, the font specifications for all but Chinese GB2312 characters have
1279 @samp{fixed} in the @var{family} field, and the font specification for
1280 Chinese GB2312 characters has a wild card @samp{*} in the @var{family}
1283 @findex create-fontset-from-fontset-spec
1284 The function that processes the fontset resource value to create the
1285 fontset is called @code{create-fontset-from-fontset-spec}. You can also
1286 call this function explicitly to create a fontset.
1288 @xref{Font X}, for more information about font naming in X.
1290 @node Undisplayable Characters
1291 @section Undisplayable Characters
1293 There may be a some non-@acronym{ASCII} characters that your terminal cannot
1294 display. Most non-windowing terminals support just a single character
1295 set (use the variable @code{default-terminal-coding-system}
1296 (@pxref{Specify Coding}) to tell Emacs which one); characters which
1297 can't be encoded in that coding system are displayed as @samp{?} by
1300 Windowing terminals can display a broader range of characters, but
1301 you may not have fonts installed for all of them; characters that have
1302 no font appear as a hollow box.
1304 If you use Latin-1 characters but your terminal can't display
1305 Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences
1306 instead, e.g.@: @samp{"o} for o-umlaut. Load the library
1307 @file{iso-ascii} to do this.
1309 @vindex latin1-display
1310 If your terminal can display Latin-1, you can display characters
1311 from other European character sets using a mixture of equivalent
1312 Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable
1313 @code{latin1-display} to enable this. The mnemonic @acronym{ASCII}
1314 sequences mostly correspond to those of the prefix input methods.
1316 @node Single-Byte Character Support
1317 @section Single-byte Character Set Support
1319 @cindex European character sets
1320 @cindex accented characters
1321 @cindex ISO Latin character sets
1322 @cindex Unibyte operation
1323 The ISO 8859 Latin-@var{n} character sets define character codes in
1324 the range 0240 to 0377 octal (160 to 255 decimal) to handle the
1325 accented letters and punctuation needed by various European languages
1326 (and some non-European ones). If you disable multibyte characters,
1327 Emacs can still handle @emph{one} of these character codes at a time.
1328 To specify @emph{which} of these codes to use, invoke @kbd{M-x
1329 set-language-environment} and specify a suitable language environment
1330 such as @samp{Latin-@var{n}}.
1332 For more information about unibyte operation, see @ref{Enabling
1333 Multibyte}. Note particularly that you probably want to ensure that
1334 your initialization files are read as unibyte if they contain non-@acronym{ASCII}
1337 @vindex unibyte-display-via-language-environment
1338 Emacs can also display those characters, provided the terminal or font
1339 in use supports them. This works automatically. Alternatively, if you
1340 are using a window system, Emacs can also display single-byte characters
1341 through fontsets, in effect by displaying the equivalent multibyte
1342 characters according to the current language environment. To request
1343 this, set the variable @code{unibyte-display-via-language-environment}
1344 to a non-@code{nil} value.
1346 @cindex @code{iso-ascii} library
1347 If your terminal does not support display of the Latin-1 character
1348 set, Emacs can display these characters as @acronym{ASCII} sequences which at
1349 least give you a clear idea of what the characters are. To do this,
1350 load the library @code{iso-ascii}. Similar libraries for other
1351 Latin-@var{n} character sets could be implemented, but we don't have
1354 @findex standard-display-8bit
1355 @cindex 8-bit display
1356 Normally non-ISO-8859 characters (decimal codes between 128 and 159
1357 inclusive) are displayed as octal escapes. You can change this for
1358 non-standard ``extended'' versions of ISO-8859 character sets by using the
1359 function @code{standard-display-8bit} in the @code{disp-table} library.
1361 There are two ways to input single-byte non-@acronym{ASCII}
1367 You can use an input method for the selected language environment.
1368 @xref{Input Methods}. When you use an input method in a unibyte buffer,
1369 the non-@acronym{ASCII} character you specify with it is converted to unibyte.
1372 If your keyboard can generate character codes 128 (decimal) and up,
1373 representing non-@acronym{ASCII} characters, you can type those character codes
1376 On a window system, you should not need to do anything special to use
1377 these keys; they should simply work. On a text-only terminal, you
1378 should use the command @code{M-x set-keyboard-coding-system} or the
1379 variable @code{keyboard-coding-system} to specify which coding system
1380 your keyboard uses (@pxref{Specify Coding}). Enabling this feature
1381 will probably require you to use @kbd{ESC} to type Meta characters;
1382 however, on a console terminal or in @code{xterm}, you can arrange for
1383 Meta to be converted to @kbd{ESC} and still be able type 8-bit
1384 characters present directly on the keyboard or using @kbd{Compose} or
1385 @kbd{AltGr} keys. @xref{User Input}.
1388 @cindex @code{iso-transl} library
1389 @cindex compose character
1390 @cindex dead character
1392 For Latin-1 only, you can use the key @kbd{C-x 8} as a ``compose
1393 character'' prefix for entry of non-@acronym{ASCII} Latin-1 printing
1394 characters. @kbd{C-x 8} is good for insertion (in the minibuffer as
1395 well as other buffers), for searching, and in any other context where
1396 a key sequence is allowed.
1398 @kbd{C-x 8} works by loading the @code{iso-transl} library. Once that
1399 library is loaded, the @key{ALT} modifier key, if the keyboard has
1400 one, serves the same purpose as @kbd{C-x 8}: use @key{ALT} together
1401 with an accent character to modify the following letter. In addition,
1402 if the keyboard has keys for the Latin-1 ``dead accent characters,''
1403 they too are defined to compose with the following character, once
1404 @code{iso-transl} is loaded.
1406 Use @kbd{C-x 8 C-h} to list all the available @kbd{C-x 8} translations.
1413 Emacs groups all supported characters into disjoint @dfn{charsets}.
1414 Each character code belongs to one and only one charset. For
1415 historical reasons, Emacs typically divides an 8-bit character code
1416 for an extended version of @acronym{ASCII} into two charsets: @acronym{ASCII}, which
1417 covers the codes 0 through 127, plus another charset which covers the
1418 ``right-hand part'' (the codes 128 and up). For instance, the
1419 characters of Latin-1 include the Emacs charset @code{ascii} plus the
1420 Emacs charset @code{latin-iso8859-1}.
1422 Emacs characters belonging to different charsets may look the same,
1423 but they are still different characters. For example, the letter
1424 @samp{o} with acute accent in charset @code{latin-iso8859-1}, used for
1425 Latin-1, is different from the letter @samp{o} with acute accent in
1426 charset @code{latin-iso8859-2}, used for Latin-2.
1428 @findex list-charset-chars
1429 @cindex characters in a certain charset
1430 @findex describe-character-set
1431 There are two commands for obtaining information about Emacs
1432 charsets. The command @kbd{M-x list-charset-chars} prompts for a name
1433 of a character set, and displays all the characters in that character
1434 set. The command @kbd{M-x describe-character-set} prompts for a
1435 charset name and displays information about that charset, including
1436 its internal representation within Emacs.
1438 To find out which charset a character in the buffer belongs to,
1439 put point before it and type @kbd{C-u C-x =}.
1442 arch-tag: 310ba60d-31ef-4ce7-91f1-f282dd57b6b3