1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1997, 1999, 2000 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 variants of the Latin alphabet, as well as Chinese,
39 Cyrillic, Devanagari (Hindi and Marathi), Ethiopic, Greek, Hebrew, IPA,
40 Japanese, Korean, Lao, Thai, Tibetan, and Vietnamese scripts. These features
41 have been merged from the modified version of Emacs known as MULE (for
42 ``MULti-lingual Enhancement to GNU Emacs'')
44 Emacs also supports various encodings of these characters used by
45 other internationalized software, such as word processors and mailers.
48 * International Intro:: Basic concepts of multibyte characters.
49 * Enabling Multibyte:: Controlling whether to use multibyte characters.
50 * Language Environments:: Setting things up for the language you use.
51 * Input Methods:: Entering text characters not on your keyboard.
52 * Select Input Method:: Specifying your choice of input methods.
53 * Multibyte Conversion:: How single-byte characters convert to multibyte.
54 * Coding Systems:: Character set conversion when you read and
55 write files, and so on.
56 * Recognize Coding:: How Emacs figures out which conversion to use.
57 * Specify Coding:: Various ways to choose which conversion to use.
58 * Fontsets:: Fontsets are collections of fonts
59 that cover the whole spectrum of characters.
60 * Defining Fontsets:: Defining a new fontset.
61 * Undisplayable Characters:: When characters don't display.
62 * Single-Byte Character Support::
63 You can pick one European character set
64 to use without multibyte characters.
67 @node International Intro
68 @section Introduction to International Character Sets
70 The users of international character sets and scripts have established
71 many more-or-less standard coding systems for storing files. Emacs
72 internally uses a single multibyte character encoding, so that it can
73 intermix characters from all these scripts in a single buffer or string.
74 This encoding represents each non-ASCII character as a sequence of bytes
75 in the range 0200 through 0377. Emacs translates between the multibyte
76 character encoding and various other coding systems when reading and
77 writing files, when exchanging data with subprocesses, and (in some
78 cases) in the @kbd{C-q} command (@pxref{Multibyte Conversion}).
81 @findex view-hello-file
82 @cindex undisplayable characters
83 @cindex @samp{?} in display
84 The command @kbd{C-h h} (@code{view-hello-file}) displays the file
85 @file{etc/HELLO}, which shows how to say ``hello'' in many languages.
86 This illustrates various scripts. If some characters can't be
87 displayed on your terminal, they appear as @samp{?} or as hollow boxes
88 (@pxref{Undisplayable Characters}).
90 Keyboards, even in the countries where these character sets are used,
91 generally don't have keys for all the characters in them. So Emacs
92 supports various @dfn{input methods}, typically one for each script or
93 language, to make it convenient to type them.
96 The prefix key @kbd{C-x @key{RET}} is used for commands that pertain
97 to multibyte characters, coding systems, and input methods.
100 @c This is commented out because it doesn't fit here, or anywhere.
101 @c This manual does not discuss "character sets" as they
102 @c are used in Mule, and it makes no sense to mention these commands
103 @c except as part of a larger discussion of the topic.
104 @c But it is not clear that topic is worth mentioning here,
105 @c since that is more of an implementation concept
106 @c than a user-level concept. And when we switch to Unicode,
107 @c character sets in the current sense may not even exist.
109 @findex list-charset-chars
110 @cindex characters in a certain charset
111 The command @kbd{M-x list-charset-chars} prompts for a name of a
112 character set, and displays all the characters in that character set.
114 @findex describe-character-set
115 @cindex character set, description
116 The command @kbd{M-x describe-character-set} prompts for a character
117 set name and displays information about that character set, including
118 its internal representation within Emacs.
121 @node Enabling Multibyte
122 @section Enabling Multibyte Characters
124 You can enable or disable multibyte character support, either for
125 Emacs as a whole, or for a single buffer. When multibyte characters are
126 disabled in a buffer, then each byte in that buffer represents a
127 character, even codes 0200 through 0377. The old features for
128 supporting the European character sets, ISO Latin-1 and ISO Latin-2,
129 work as they did in Emacs 19 and also work for the other ISO 8859
132 However, there is no need to turn off multibyte character support to
133 use ISO Latin; the Emacs multibyte character set includes all the
134 characters in these character sets, and Emacs can translate
135 automatically to and from the ISO codes.
137 To edit a particular file in unibyte representation, visit it using
138 @code{find-file-literally}. @xref{Visiting}. To convert a buffer in
139 multibyte representation into a single-byte representation of the same
140 characters, the easiest way is to save the contents in a file, kill the
141 buffer, and find the file again with @code{find-file-literally}. You
142 can also use @kbd{C-x @key{RET} c}
143 (@code{universal-coding-system-argument}) and specify @samp{raw-text} as
144 the coding system with which to find or save a file. @xref{Specify
145 Coding}. Finding a file as @samp{raw-text} doesn't disable format
146 conversion, uncompression and auto mode selection as
147 @code{find-file-literally} does.
149 @vindex enable-multibyte-characters
150 @vindex default-enable-multibyte-characters
151 To turn off multibyte character support by default, start Emacs with
152 the @samp{--unibyte} option (@pxref{Initial Options}), or set the
153 environment variable @env{EMACS_UNIBYTE}. You can also customize
154 @code{enable-multibyte-characters} or, equivalently, directly set the
155 variable @code{default-enable-multibyte-characters} in your init file to
156 have basically the same effect as @samp{--unibyte}.
158 @cindex Lisp files, and multibyte operation
159 @cindex multibyte operation, and Lisp files
160 @cindex unibyte operation, and Lisp files
161 @cindex init file, and non-ASCII characters
162 @cindex environment variables, and non-ASCII characters
163 With @samp{--unibyte}, multibyte strings are not created during
164 initialization from the values of environment variables,
165 @file{/etc/passwd} entries etc.@: that contain non-ASCII 8-bit
168 Emacs normally loads Lisp files as multibyte, regardless of whether
169 you used @samp{--unibyte}. This includes the Emacs initialization
170 file, @file{.emacs}, and the initialization files of Emacs packages
171 such as Gnus. However, you can specify unibyte loading for a
172 particular Lisp file, by putting @samp{-*-unibyte: t;-*-} in a comment
173 on the first line. Then that file is always loaded as unibyte text,
174 even if you did not start Emacs with @samp{--unibyte}. The motivation
175 for these conventions is that it is more reliable to always load any
176 particular Lisp file in the same way. However, you can load a Lisp
177 file as unibyte, on any one occasion, by typing @kbd{C-x @key{RET} c
178 raw-text @key{RET}} immediately before loading it.
180 The mode line indicates whether multibyte character support is enabled
181 in the current buffer. If it is, there are two or more characters (most
182 often two dashes) before the colon near the beginning of the mode line.
183 When multibyte characters are not enabled, just one dash precedes the
186 @node Language Environments
187 @section Language Environments
188 @cindex language environments
190 All supported character sets are supported in Emacs buffers whenever
191 multibyte characters are enabled; there is no need to select a
192 particular language in order to display its characters in an Emacs
193 buffer. However, it is important to select a @dfn{language environment}
194 in order to set various defaults. The language environment really
195 represents a choice of preferred script (more or less) rather than a
198 The language environment controls which coding systems to recognize
199 when reading text (@pxref{Recognize Coding}). This applies to files,
200 incoming mail, netnews, and any other text you read into Emacs. It may
201 also specify the default coding system to use when you create a file.
202 Each language environment also specifies a default input method.
204 @findex set-language-environment
205 @vindex current-language-environment
206 To select a language environment, customize the option
207 @code{current-language-environment} or use the command @kbd{M-x
208 set-language-environment}. It makes no difference which buffer is
209 current when you use this command, because the effects apply globally to
210 the Emacs session. The supported language environments include:
214 Chinese-BIG5, Chinese-CNS, Chinese-GB, Cyrillic-ALT, Cyrillic-ISO,
215 Cyrillic-KOI8, Czech, Devanagari, English, Ethiopic, German, Greek,
216 Hebrew, IPA, Japanese, Korean, Lao, Latin-1, Latin-2, Latin-3, Latin-4,
217 Latin-5, Latin-8 (Celtic), Latin-9 (updated Latin-1, with the Euro
218 sign), Polish, Romanian, Slovak, Slovenian, Thai, Tibetan, Turkish,
219 Dutch, Spanish, and Vietnamese.
222 @cindex fonts for various scripts
223 @cindex Intlfonts package, installation
224 To display the script(s) used by your language environment on a
225 graphical display, you need to have a suitable font. If some of the
226 characters appear as empty boxes, you should install the GNU Intlfonts
227 package, which includes fonts for all supported scripts.@footnote{If
228 you run Emacs on X, you need to inform the X server about the location
229 of the newly installed fonts with the following commands:
232 xset fp+ /usr/local/share/emacs/fonts
236 @xref{Fontsets}, for more details about setting up your fonts.
238 @findex set-locale-environment
239 @vindex locale-language-names
240 @vindex locale-charset-language-names
242 Some operating systems let you specify the language you are using by
243 setting the locale environment variables @env{LC_ALL}, @env{LC_CTYPE},
244 or @env{LANG}.@footnote{If more than one of these is set, the first
245 one that is nonempty specifies your locale for this purpose.} Emacs
246 handles this during startup by matching your locale against entries in
247 the value of the variables @code{locale-charset-language-names} and
248 @code{locale-language-names} and selects the corresponding language
249 environment if a match is found. (The former variable overrides the
250 latter.) It also adjusts the display table and terminal coding
251 system, the locale coding system, and the preferred coding system as
252 needed for the locale.
254 If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG}
255 environment variables while running Emacs, you may want to invoke the
256 @code{set-locale-environment} function afterwards to readjust the
257 language environment from the new locale.
259 @vindex locale-preferred-coding-systems
260 The @code{set-locale-environment} function normally uses the preferred
261 coding system established by the language environment to decode system
262 messages. But if your locale matches an entry in the variable
263 @code{locale-preferred-coding-systems}, Emacs uses the corresponding
264 coding system instead. For example, if the locale @samp{ja_JP.PCK}
265 matches @code{japanese-shift-jis} in
266 @code{locale-preferred-coding-systems}, Emacs uses that encoding even
267 though it might normally use @code{japanese-iso-8bit}.
269 You can override the language environment chosen at startup with
270 explicit use of the command @code{set-language-environment}, or with
271 customization of @code{current-language-environment} in your init
275 @findex describe-language-environment
276 To display information about the effects of a certain language
277 environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env}
278 @key{RET}} (@code{describe-language-environment}). This tells you which
279 languages this language environment is useful for, and lists the
280 character sets, coding systems, and input methods that go with it. It
281 also shows some sample text to illustrate scripts used in this language
282 environment. By default, this command describes the chosen language
285 @vindex set-language-environment-hook
286 You can customize any language environment with the normal hook
287 @code{set-language-environment-hook}. The command
288 @code{set-language-environment} runs that hook after setting up the new
289 language environment. The hook functions can test for a specific
290 language environment by checking the variable
291 @code{current-language-environment}. This hook is where you should
292 put non-default settings for specific language environment, such as
293 coding systems for keyboard input and terminal output, the default
296 @vindex exit-language-environment-hook
297 Before it starts to set up the new language environment,
298 @code{set-language-environment} first runs the hook
299 @code{exit-language-environment-hook}. This hook is useful for undoing
300 customizations that were made with @code{set-language-environment-hook}.
301 For instance, if you set up a special key binding in a specific language
302 environment using @code{set-language-environment-hook}, you should set
303 up @code{exit-language-environment-hook} to restore the normal binding
307 @section Input Methods
309 @cindex input methods
310 An @dfn{input method} is a kind of character conversion designed
311 specifically for interactive input. In Emacs, typically each language
312 has its own input method; sometimes several languages which use the same
313 characters can share one input method. A few languages support several
316 The simplest kind of input method works by mapping ASCII letters
317 into another alphabet; this allows you to type characters which your
318 keyboard doesn't support directly. This is how the Greek and Russian
321 A more powerful technique is composition: converting sequences of
322 characters into one letter. Many European input methods use composition
323 to produce a single non-ASCII letter from a sequence that consists of a
324 letter followed by accent characters (or vice versa). For example, some
325 methods convert the sequence @kbd{a'} into a single accented letter.
326 These input methods have no special commands of their own; all they do
327 is compose sequences of printing characters.
329 The input methods for syllabic scripts typically use mapping followed
330 by composition. The input methods for Thai and Korean work this way.
331 First, letters are mapped into symbols for particular sounds or tone
332 marks; then, sequences of these which make up a whole syllable are
333 mapped into one syllable sign.
335 Chinese and Japanese require more complex methods. In Chinese input
336 methods, first you enter the phonetic spelling of a Chinese word (in
337 input method @code{chinese-py}, among others), or a sequence of portions
338 of the character (input methods @code{chinese-4corner} and
339 @code{chinese-sw}, and others). Since one phonetic spelling typically
340 corresponds to many different Chinese characters, you must select one of
341 the alternatives using special Emacs commands. Keys such as @kbd{C-f},
342 @kbd{C-b}, @kbd{C-n}, @kbd{C-p}, and digits have special definitions in
343 this situation, used for selecting among the alternatives. @key{TAB}
344 displays a buffer showing all the possibilities.
346 In Japanese input methods, first you input a whole word using
347 phonetic spelling; then, after the word is in the buffer, Emacs converts
348 it into one or more characters using a large dictionary. One phonetic
349 spelling corresponds to many differently written Japanese words, so you
350 must select one of them; use @kbd{C-n} and @kbd{C-p} to cycle through
353 Sometimes it is useful to cut off input method processing so that the
354 characters you have just entered will not combine with subsequent
355 characters. For example, in input method @code{latin-1-postfix}, the
356 sequence @kbd{e '} combines to form an @samp{e} with an accent. What if
357 you want to enter them as separate characters?
359 One way is to type the accent twice; that is a special feature for
360 entering the separate letter and accent. For example, @kbd{e ' '} gives
361 you the two characters @samp{e'}. Another way is to type another letter
362 after the @kbd{e}---something that won't combine with that---and
363 immediately delete it. For example, you could type @kbd{e e @key{DEL}
364 '} to get separate @samp{e} and @samp{'}.
366 Another method, more general but not quite as easy to type, is to use
367 @kbd{C-\ C-\} between two characters to stop them from combining. This
368 is the command @kbd{C-\} (@code{toggle-input-method}) used twice.
370 @xref{Select Input Method}.
373 @cindex incremental search, input method interference
374 @kbd{C-\ C-\} is especially useful inside an incremental search,
375 because it stops waiting for more characters to combine, and starts
376 searching for what you have already entered.
378 @vindex input-method-verbose-flag
379 @vindex input-method-highlight-flag
380 The variables @code{input-method-highlight-flag} and
381 @code{input-method-verbose-flag} control how input methods explain what
382 is happening. If @code{input-method-highlight-flag} is non-@code{nil},
383 the partial sequence is highlighted in the buffer. If
384 @code{input-method-verbose-flag} is non-@code{nil}, the list of possible
385 characters to type next is displayed in the echo area (but not when you
386 are in the minibuffer).
389 Input methods are implemented in the separate Leim package: they are
390 available only if the system administrator used Leim when building
391 Emacs. If Emacs was built without Leim, you will find that no input
394 @node Select Input Method
395 @section Selecting an Input Method
399 Enable or disable use of the selected input method.
401 @item C-x @key{RET} C-\ @var{method} @key{RET}
402 Select a new input method for the current buffer.
404 @item C-h I @var{method} @key{RET}
405 @itemx C-h C-\ @var{method} @key{RET}
406 @findex describe-input-method
409 Describe the input method @var{method} (@code{describe-input-method}).
410 By default, it describes the current input method (if any). This
411 description should give you the full details of how to use any
412 particular input method.
414 @item M-x list-input-methods
415 Display a list of all the supported input methods.
418 @findex set-input-method
419 @vindex current-input-method
421 To choose an input method for the current buffer, use @kbd{C-x
422 @key{RET} C-\} (@code{set-input-method}). This command reads the
423 input method name with the minibuffer; the name normally starts with the
424 language environment that it is meant to be used with. The variable
425 @code{current-input-method} records which input method is selected.
427 @findex toggle-input-method
429 Input methods use various sequences of ASCII characters to stand for
430 non-ASCII characters. Sometimes it is useful to turn off the input
431 method temporarily. To do this, type @kbd{C-\}
432 (@code{toggle-input-method}). To reenable the input method, type
435 If you type @kbd{C-\} and you have not yet selected an input method,
436 it prompts for you to specify one. This has the same effect as using
437 @kbd{C-x @key{RET} C-\} to specify an input method.
439 When invoked with a numeric argument, as in @kbd{C-u C-\},
440 @code{toggle-input-method} always prompts you for an input method,
441 suggesting the most recently selected one as the default.
443 @vindex default-input-method
444 Selecting a language environment specifies a default input method for
445 use in various buffers. When you have a default input method, you can
446 select it in the current buffer by typing @kbd{C-\}. The variable
447 @code{default-input-method} specifies the default input method
448 (@code{nil} means there is none).
450 In some language environments, which support several different input
451 methods, you might want to use an input method different from the
452 default chosen by @code{set-language-environment}. You can instruct
453 Emacs to select a different default input method for a certain
454 language environment if you by using
455 @code{set-language-environment-hook} (@pxref{Language Environments,
456 set-language-environment-hook}). For example:
459 (defun my-chinese-setup ()
460 "Set up my private Chinese environment."
461 (if (equal current-language-environment "Chinese-GB")
462 (setq default-input-method "chinese-tonepy")))
463 (add-hook 'set-language-environment-hook 'my-chinese-setup)
467 This sets the default input method to be @code{chinese-tonepy}
468 whenever you choose a Chinese-GB language environment.
470 @findex quail-set-keyboard-layout
471 Some input methods for alphabetic scripts work by (in effect)
472 remapping the keyboard to emulate various keyboard layouts commonly used
473 for those scripts. How to do this remapping properly depends on your
474 actual keyboard layout. To specify which layout your keyboard has, use
475 the command @kbd{M-x quail-set-keyboard-layout}.
477 @findex list-input-methods
478 To display a list of all the supported input methods, type @kbd{M-x
479 list-input-methods}. The list gives information about each input
480 method, including the string that stands for it in the mode line.
482 @node Multibyte Conversion
483 @section Unibyte and Multibyte Non-ASCII characters
485 When multibyte characters are enabled, character codes 0240 (octal)
486 through 0377 (octal) are not really legitimate in the buffer. The valid
487 non-ASCII printing characters have codes that start from 0400.
489 If you type a self-inserting character in the range 0240 through
490 0377, or if you use @kbd{C-q} to insert one, Emacs assumes you
491 intended to use one of the ISO Latin-@var{n} character sets, and
492 converts it to the Emacs code representing that Latin-@var{n}
493 character. You select @emph{which} ISO Latin character set to use
494 through your choice of language environment
499 (@pxref{Language Environments}).
501 If you do not specify a choice, the default is Latin-1.
503 If you insert a character in the range 0200 through 0237, which
504 forms the @code{eight-bit-control} character set, it is inserted
505 literally. You should normally avoid doing this since buffers
506 containing such characters have to be written out in either the
507 @code{emacs-mule} or @code{raw-text} coding system, which is usually
511 @section Coding Systems
512 @cindex coding systems
514 Users of various languages have established many more-or-less standard
515 coding systems for representing them. Emacs does not use these coding
516 systems internally; instead, it converts from various coding systems to
517 its own system when reading data, and converts the internal coding
518 system to other coding systems when writing data. Conversion is
519 possible in reading or writing files, in sending or receiving from the
520 terminal, and in exchanging data with subprocesses.
522 Emacs assigns a name to each coding system. Most coding systems are
523 used for one language, and the name of the coding system starts with the
524 language name. Some coding systems are used for several languages;
525 their names usually start with @samp{iso}. There are also special
526 coding systems @code{no-conversion}, @code{raw-text} and
527 @code{emacs-mule} which do not convert printing characters at all.
529 A special class of coding systems, collectively known as
530 @dfn{codepages}, is designed to support text encoded by MS-Windows and
531 MS-DOS software. To use any of these systems, you need to create it
532 with @kbd{M-x codepage-setup}. @xref{MS-DOS and MULE}.
534 In addition to converting various representations of non-ASCII
535 characters, a coding system can perform end-of-line conversion. Emacs
536 handles three different conventions for how to separate lines in a file:
537 newline, carriage-return linefeed, and just carriage-return.
540 @item C-h C @var{coding} @key{RET}
541 Describe coding system @var{coding}.
543 @item C-h C @key{RET}
544 Describe the coding systems currently in use.
546 @item M-x list-coding-systems
547 Display a list of all the supported coding systems.
551 @findex describe-coding-system
552 The command @kbd{C-h C} (@code{describe-coding-system}) displays
553 information about particular coding systems. You can specify a coding
554 system name as argument; alternatively, with an empty argument, it
555 describes the coding systems currently selected for various purposes,
556 both in the current buffer and as the defaults, and the priority list
557 for recognizing coding systems (@pxref{Recognize Coding}).
559 @findex list-coding-systems
560 To display a list of all the supported coding systems, type @kbd{M-x
561 list-coding-systems}. The list gives information about each coding
562 system, including the letter that stands for it in the mode line
565 @cindex end-of-line conversion
566 @cindex MS-DOS end-of-line conversion
567 @cindex Macintosh end-of-line conversion
568 Each of the coding systems that appear in this list---except for
569 @code{no-conversion}, which means no conversion of any kind---specifies
570 how and whether to convert printing characters, but leaves the choice of
571 end-of-line conversion to be decided based on the contents of each file.
572 For example, if the file appears to use the sequence carriage-return
573 linefeed to separate lines, DOS end-of-line conversion will be used.
575 Each of the listed coding systems has three variants which specify
576 exactly what to do for end-of-line conversion:
580 Don't do any end-of-line conversion; assume the file uses
581 newline to separate lines. (This is the convention normally used
582 on Unix and GNU systems.)
585 Assume the file uses carriage-return linefeed to separate lines, and do
586 the appropriate conversion. (This is the convention normally used on
587 Microsoft systems.@footnote{It is also specified for MIME @samp{text/*}
588 bodies and in other network transport contexts. It is different
589 from the SGML reference syntax record-start/record-end format which
590 Emacs doesn't support directly.})
593 Assume the file uses carriage-return to separate lines, and do the
594 appropriate conversion. (This is the convention normally used on the
598 These variant coding systems are omitted from the
599 @code{list-coding-systems} display for brevity, since they are entirely
600 predictable. For example, the coding system @code{iso-latin-1} has
601 variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and
602 @code{iso-latin-1-mac}.
604 The coding system @code{raw-text} is good for a file which is mainly
605 ASCII text, but may contain byte values above 127 which are not meant to
606 encode non-ASCII characters. With @code{raw-text}, Emacs copies those
607 byte values unchanged, and sets @code{enable-multibyte-characters} to
608 @code{nil} in the current buffer so that they will be interpreted
609 properly. @code{raw-text} handles end-of-line conversion in the usual
610 way, based on the data encountered, and has the usual three variants to
611 specify the kind of end-of-line conversion to use.
613 In contrast, the coding system @code{no-conversion} specifies no
614 character code conversion at all---none for non-ASCII byte values and
615 none for end of line. This is useful for reading or writing binary
616 files, tar files, and other files that must be examined verbatim. It,
617 too, sets @code{enable-multibyte-characters} to @code{nil}.
619 The easiest way to edit a file with no conversion of any kind is with
620 the @kbd{M-x find-file-literally} command. This uses
621 @code{no-conversion}, and also suppresses other Emacs features that
622 might convert the file contents before you see them. @xref{Visiting}.
624 The coding system @code{emacs-mule} means that the file contains
625 non-ASCII characters stored with the internal Emacs encoding. It
626 handles end-of-line conversion based on the data encountered, and has
627 the usual three variants to specify the kind of end-of-line conversion.
629 @node Recognize Coding
630 @section Recognizing Coding Systems
632 Most of the time, Emacs can recognize which coding system to use for
633 any given file---once you have specified your preferences.
635 Some coding systems can be recognized or distinguished by which byte
636 sequences appear in the data. However, there are coding systems that
637 cannot be distinguished, not even potentially. For example, there is no
638 way to distinguish between Latin-1 and Latin-2; they use the same byte
639 values with different meanings.
641 Emacs handles this situation by means of a priority list of coding
642 systems. Whenever Emacs reads a file, if you do not specify the coding
643 system to use, Emacs checks the data against each coding system,
644 starting with the first in priority and working down the list, until it
645 finds a coding system that fits the data. Then it converts the file
646 contents assuming that they are represented in this coding system.
648 The priority list of coding systems depends on the selected language
649 environment (@pxref{Language Environments}). For example, if you use
650 French, you probably want Emacs to prefer Latin-1 to Latin-2; if you use
651 Czech, you probably want Latin-2 to be preferred. This is one of the
652 reasons to specify a language environment.
654 @findex prefer-coding-system
655 However, you can alter the priority list in detail with the command
656 @kbd{M-x prefer-coding-system}. This command reads the name of a coding
657 system from the minibuffer, and adds it to the front of the priority
658 list, so that it is preferred to all others. If you use this command
659 several times, each use adds one element to the front of the priority
662 If you use a coding system that specifies the end-of-line conversion
663 type, such as @code{iso-8859-1-dos}, what that means is that Emacs
664 should attempt to recognize @code{iso-8859-1} with priority, and should
665 use DOS end-of-line conversion in case it recognizes @code{iso-8859-1}.
667 @vindex file-coding-system-alist
668 Sometimes a file name indicates which coding system to use for the
669 file. The variable @code{file-coding-system-alist} specifies this
670 correspondence. There is a special function
671 @code{modify-coding-system-alist} for adding elements to this list. For
672 example, to read and write all @samp{.txt} files using the coding system
673 @code{china-iso-8bit}, you can execute this Lisp expression:
676 (modify-coding-system-alist 'file "\\.txt\\'" 'china-iso-8bit)
680 The first argument should be @code{file}, the second argument should be
681 a regular expression that determines which files this applies to, and
682 the third argument says which coding system to use for these files.
684 @vindex inhibit-eol-conversion
685 @cindex DOS-style end-of-line display
686 Emacs recognizes which kind of end-of-line conversion to use based on
687 the contents of the file: if it sees only carriage-returns, or only
688 carriage-return linefeed sequences, then it chooses the end-of-line
689 conversion accordingly. You can inhibit the automatic use of
690 end-of-line conversion by setting the variable @code{inhibit-eol-conversion}
691 to non-@code{nil}. If you do that, DOS-style files will be displayed
692 with the @samp{^M} characters visible in the buffer; some people
693 prefer this to the more subtle @samp{(DOS)} end-of-line type
694 indication near the left edge of the mode line (@pxref{Mode Line,
697 @vindex inhibit-iso-escape-detection
698 @cindex escape sequences in files
699 By default, the automatic detection of coding system is sensitive to
700 escape sequences. If Emacs sees a sequence of characters that begin
701 with an escape character, and the sequence is valid as an ISO-2022
702 code, that tells Emacs to use one of the ISO-2022 encodings to decode
705 However, there may be cases that you want to read escape sequences
706 in a file as is. In such a case, you can set the variable
707 @code{inhibit-iso-escape-detection} to non-@code{nil}. Then the code
708 detection ignores any escape sequences, and never uses an ISO-2022
709 encoding. The result is that all escape sequences become visible in
712 The default value of @code{inhibit-iso-escape-detection} is
713 @code{nil}. We recommend that you not change it permanently, only for
714 one specific operation. That's because many Emacs Lisp source files
715 that contain non-ASCII characters are encoded in the coding system
716 @code{iso-2022-7bit} in the Emacs distribution, and they won't be
717 decoded correctly when you visit those files if you suppress the
718 escape sequence detection.
721 You can specify the coding system for a particular file using the
722 @samp{-*-@dots{}-*-} construct at the beginning of a file, or a local
723 variables list at the end (@pxref{File Variables}). You do this by
724 defining a value for the ``variable'' named @code{coding}. Emacs does
725 not really have a variable @code{coding}; instead of setting a variable,
726 it uses the specified coding system for the file. For example,
727 @samp{-*-mode: C; coding: latin-1;-*-} specifies use of the Latin-1
728 coding system, as well as C mode. If you specify the coding explicitly
729 in the file, that overrides @code{file-coding-system-alist}.
731 @vindex auto-coding-alist
732 The variable @code{auto-coding-alist} is the strongest way to specify
733 the coding system for certain patterns of file names; this variable even
734 overrides @samp{-*-coding:-*-} tags in the file itself. Emacs uses this
735 feature for tar and archive files, to prevent Emacs from being confused
736 by a @samp{-*-coding:-*-} tag in a member of the archive and thinking it
737 applies to the archive file as a whole.
739 @vindex buffer-file-coding-system
740 Once Emacs has chosen a coding system for a buffer, it stores that
741 coding system in @code{buffer-file-coding-system} and uses that coding
742 system, by default, for operations that write from this buffer into a
743 file. This includes the commands @code{save-buffer} and
744 @code{write-region}. If you want to write files from this buffer using
745 a different coding system, you can specify a different coding system for
746 the buffer using @code{set-buffer-file-coding-system} (@pxref{Specify
749 You can insert any possible character into any Emacs buffer, but
750 most coding systems can only handle some of the possible characters.
751 This means that you can insert characters that cannot be encoded with
752 the coding system that will be used to save the buffer. For example,
753 you could start with an ASCII file and insert a few Latin-1 characters
754 into it, or you could edit a text file in Polish encoded in
755 @code{iso-8859-2} and add to it translations of several Polish words
756 into Russian. When you save the buffer, Emacs cannot use the current
757 value of @code{buffer-file-coding-system}, because the characters you
758 added cannot be encoded by that coding system.
760 When that happens, Emacs tries the most-preferred coding system (set
761 by @kbd{M-x prefer-coding-system} or @kbd{M-x
762 set-language-environment}), and if that coding system can safely
763 encode all of the characters in the buffer, Emacs uses it, and stores
764 its value in @code{buffer-file-coding-system}. Otherwise, Emacs
765 displays a list of coding systems suitable for encoding the buffer's
766 contents, and asks to choose one of those coding systems.
768 If you insert the unsuitable characters in a mail message, Emacs
769 behaves a bit differently. It additionally checks whether the
770 most-preferred coding system is recommended for use in MIME messages;
771 if it isn't, Emacs tells you that the most-preferred coding system is
772 not recommended and prompts you for another coding system. This is so
773 you won't inadvertently send a message encoded in a way that your
774 recipient's mail software will have difficulty decoding. (If you do
775 want to use the most-preferred coding system, you can type its name to
776 Emacs prompt anyway.)
778 @vindex sendmail-coding-system
779 When you send a message with Mail mode (@pxref{Sending Mail}), Emacs has
780 four different ways to determine the coding system to use for encoding
781 the message text. It tries the buffer's own value of
782 @code{buffer-file-coding-system}, if that is non-@code{nil}. Otherwise,
783 it uses the value of @code{sendmail-coding-system}, if that is
784 non-@code{nil}. The third way is to use the default coding system for
785 new files, which is controlled by your choice of language environment,
786 if that is non-@code{nil}. If all of these three values are @code{nil},
787 Emacs encodes outgoing mail using the Latin-1 coding system.
789 @vindex rmail-decode-mime-charset
790 When you get new mail in Rmail, each message is translated
791 automatically from the coding system it is written in---as if it were a
792 separate file. This uses the priority list of coding systems that you
793 have specified. If a MIME message specifies a character set, Rmail
794 obeys that specification, unless @code{rmail-decode-mime-charset} is
797 @vindex rmail-file-coding-system
798 For reading and saving Rmail files themselves, Emacs uses the coding
799 system specified by the variable @code{rmail-file-coding-system}. The
800 default value is @code{nil}, which means that Rmail files are not
801 translated (they are read and written in the Emacs internal character
805 @section Specifying a Coding System
807 In cases where Emacs does not automatically choose the right coding
808 system, you can use these commands to specify one:
811 @item C-x @key{RET} f @var{coding} @key{RET}
812 Use coding system @var{coding} for the visited file
813 in the current buffer.
815 @item C-x @key{RET} c @var{coding} @key{RET}
816 Specify coding system @var{coding} for the immediately following
819 @item C-x @key{RET} k @var{coding} @key{RET}
820 Use coding system @var{coding} for keyboard input.
822 @item C-x @key{RET} t @var{coding} @key{RET}
823 Use coding system @var{coding} for terminal output.
825 @item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET}
826 Use coding systems @var{input-coding} and @var{output-coding} for
827 subprocess input and output in the current buffer.
829 @item C-x @key{RET} x @var{coding} @key{RET}
830 Use coding system @var{coding} for transferring selections to and from
831 other programs through the window system.
833 @item C-x @key{RET} X @var{coding} @key{RET}
834 Use coding system @var{coding} for transferring @emph{one}
835 selection---the next one---to or from the window system.
839 @findex set-buffer-file-coding-system
840 The command @kbd{C-x @key{RET} f} (@code{set-buffer-file-coding-system})
841 specifies the file coding system for the current buffer---in other
842 words, which coding system to use when saving or rereading the visited
843 file. You specify which coding system using the minibuffer. Since this
844 command applies to a file you have already visited, it affects only the
845 way the file is saved.
848 @findex universal-coding-system-argument
849 Another way to specify the coding system for a file is when you visit
850 the file. First use the command @kbd{C-x @key{RET} c}
851 (@code{universal-coding-system-argument}); this command uses the
852 minibuffer to read a coding system name. After you exit the minibuffer,
853 the specified coding system is used for @emph{the immediately following
856 So if the immediately following command is @kbd{C-x C-f}, for example,
857 it reads the file using that coding system (and records the coding
858 system for when the file is saved). Or if the immediately following
859 command is @kbd{C-x C-w}, it writes the file using that coding system.
860 Other file commands affected by a specified coding system include
861 @kbd{C-x C-i} and @kbd{C-x C-v}, as well as the other-window variants of
864 @kbd{C-x @key{RET} c} also affects commands that start subprocesses,
865 including @kbd{M-x shell} (@pxref{Shell}).
867 However, if the immediately following command does not use the coding
868 system, then @kbd{C-x @key{RET} c} ultimately has no effect.
870 An easy way to visit a file with no conversion is with the @kbd{M-x
871 find-file-literally} command. @xref{Visiting}.
873 @vindex default-buffer-file-coding-system
874 The variable @code{default-buffer-file-coding-system} specifies the
875 choice of coding system to use when you create a new file. It applies
876 when you find a new file, and when you create a buffer and then save it
877 in a file. Selecting a language environment typically sets this
878 variable to a good choice of default coding system for that language
882 @findex set-terminal-coding-system
883 The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system})
884 specifies the coding system for terminal output. If you specify a
885 character code for terminal output, all characters output to the
886 terminal are translated into that coding system.
888 This feature is useful for certain character-only terminals built to
889 support specific languages or character sets---for example, European
890 terminals that support one of the ISO Latin character sets. You need to
891 specify the terminal coding system when using multibyte text, so that
892 Emacs knows which characters the terminal can actually handle.
894 By default, output to the terminal is not translated at all, unless
895 Emacs can deduce the proper coding system from your terminal type or
896 your locale specification (@pxref{Language Environments}).
899 @findex set-keyboard-coding-system
900 @vindex keyboard-coding-system
901 The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system})
902 or the Custom option @code{keyboard-coding-system}
903 specifies the coding system for keyboard input. Character-code
904 translation of keyboard input is useful for terminals with keys that
905 send non-ASCII graphic characters---for example, some terminals designed
906 for ISO Latin-1 or subsets of it.
908 By default, keyboard input is not translated at all.
910 There is a similarity between using a coding system translation for
911 keyboard input, and using an input method: both define sequences of
912 keyboard input that translate into single characters. However, input
913 methods are designed to be convenient for interactive use by humans, and
914 the sequences that are translated are typically sequences of ASCII
915 printing characters. Coding systems typically translate sequences of
916 non-graphic characters.
920 @findex set-selection-coding-system
921 @findex set-next-selection-coding-system
922 The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system})
923 specifies the coding system for sending selected text to the window
924 system, and for receiving the text of selections made in other
925 applications. This command applies to all subsequent selections, until
926 you override it by using the command again. The command @kbd{C-x
927 @key{RET} X} (@code{set-next-selection-coding-system}) specifies the
928 coding system for the next selection made in Emacs or read by Emacs.
931 @findex set-buffer-process-coding-system
932 The command @kbd{C-x @key{RET} p} (@code{set-buffer-process-coding-system})
933 specifies the coding system for input and output to a subprocess. This
934 command applies to the current buffer; normally, each subprocess has its
935 own buffer, and thus you can use this command to specify translation to
936 and from a particular subprocess by giving the command in the
937 corresponding buffer.
939 The default for translation of process input and output depends on the
940 current language environment.
942 @vindex file-name-coding-system
943 @cindex file names with non-ASCII characters
944 The variable @code{file-name-coding-system} specifies a coding system
945 to use for encoding file names. If you set the variable to a coding
946 system name (as a Lisp symbol or a string), Emacs encodes file names
947 using that coding system for all file operations. This makes it
948 possible to use non-ASCII characters in file names---or, at least, those
949 non-ASCII characters which the specified coding system can encode.
951 If @code{file-name-coding-system} is @code{nil}, Emacs uses a default
952 coding system determined by the selected language environment. In the
953 default language environment, any non-ASCII characters in file names are
954 not encoded specially; they appear in the file system using the internal
955 Emacs representation.
957 @strong{Warning:} if you change @code{file-name-coding-system} (or the
958 language environment) in the middle of an Emacs session, problems can
959 result if you have already visited files whose names were encoded using
960 the earlier coding system and cannot be encoded (or are encoded
961 differently) under the new coding system. If you try to save one of
962 these buffers under the visited file name, saving may use the wrong file
963 name, or it may get an error. If such a problem happens, use @kbd{C-x
964 C-w} to specify a new file name for that buffer.
966 @vindex locale-coding-system
967 The variable @code{locale-coding-system} specifies a coding system
968 to use when encoding and decoding system strings such as system error
969 messages and @code{format-time-string} formats and time stamps. You
970 should choose a coding system that is compatible with the underlying
971 system's text representation, which is normally specified by one of
972 the environment variables @env{LC_ALL}, @env{LC_CTYPE}, and
973 @env{LANG}. (The first one whose value is nonempty is the one that
974 determines the text representation.)
980 A font for X typically defines shapes for one alphabet or script.
981 Therefore, displaying the entire range of scripts that Emacs supports
982 requires a collection of many fonts. In Emacs, such a collection is
983 called a @dfn{fontset}. A fontset is defined by a list of fonts, each
984 assigned to handle a range of character codes.
986 Each fontset has a name, like a font. The available X fonts are
987 defined by the X server; fontsets, however, are defined within Emacs
988 itself. Once you have defined a fontset, you can use it within Emacs by
989 specifying its name, anywhere that you could use a single font. Of
990 course, Emacs fontsets can use only the fonts that the X server
991 supports; if certain characters appear on the screen as hollow boxes,
992 this means that the fontset in use for them has no font for those
993 characters.@footnote{The Emacs installation instructions have information on
994 additional font support.}
996 Emacs creates two fontsets automatically: the @dfn{standard fontset}
997 and the @dfn{startup fontset}. The standard fontset is most likely to
998 have fonts for a wide variety of non-ASCII characters; however, this is
999 not the default for Emacs to use. (By default, Emacs tries to find a
1000 font which has bold and italic variants.) You can specify use of the
1001 standard fontset with the @samp{-fn} option, or with the @samp{Font} X
1002 resource (@pxref{Font X}). For example,
1005 emacs -fn fontset-standard
1008 A fontset does not necessarily specify a font for every character
1009 code. If a fontset specifies no font for a certain character, or if it
1010 specifies a font that does not exist on your system, then it cannot
1011 display that character properly. It will display that character as an
1014 @vindex highlight-wrong-size-font
1015 The fontset height and width are determined by the ASCII characters
1016 (that is, by the font used for ASCII characters in that fontset). If
1017 another font in the fontset has a different height, or a different
1018 width, then characters assigned to that font are clipped to the
1019 fontset's size. If @code{highlight-wrong-size-font} is non-@code{nil},
1020 a box is displayed around these wrong-size characters as well.
1022 @node Defining Fontsets
1023 @section Defining fontsets
1025 @vindex standard-fontset-spec
1026 @cindex standard fontset
1027 Emacs creates a standard fontset automatically according to the value
1028 of @code{standard-fontset-spec}. This fontset's name is
1031 -*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard
1035 or just @samp{fontset-standard} for short.
1037 Bold, italic, and bold-italic variants of the standard fontset are
1038 created automatically. Their names have @samp{bold} instead of
1039 @samp{medium}, or @samp{i} instead of @samp{r}, or both.
1041 @cindex startup fontset
1042 If you specify a default ASCII font with the @samp{Font} resource or
1043 the @samp{-fn} argument, Emacs generates a fontset from it
1044 automatically. This is the @dfn{startup fontset} and its name is
1045 @code{fontset-startup}. It does this by replacing the @var{foundry},
1046 @var{family}, @var{add_style}, and @var{average_width} fields of the
1047 font name with @samp{*}, replacing @var{charset_registry} field with
1048 @samp{fontset}, and replacing @var{charset_encoding} field with
1049 @samp{startup}, then using the resulting string to specify a fontset.
1051 For instance, if you start Emacs this way,
1054 emacs -fn "*courier-medium-r-normal--14-140-*-iso8859-1"
1058 Emacs generates the following fontset and uses it for the initial X
1062 -*-*-medium-r-normal-*-14-140-*-*-*-*-fontset-startup
1065 With the X resource @samp{Emacs.Font}, you can specify a fontset name
1066 just like an actual font name. But be careful not to specify a fontset
1067 name in a wildcard resource like @samp{Emacs*Font}---that wildcard
1068 specification applies to various other purposes, such as menus, and
1069 menus cannot handle fontsets.
1071 You can specify additional fontsets using X resources named
1072 @samp{Fontset-@var{n}}, where @var{n} is an integer starting from 0.
1073 The resource value should have this form:
1076 @var{fontpattern}, @r{[}@var{charsetname}:@var{fontname}@r{]@dots{}}
1080 @var{fontpattern} should have the form of a standard X font name, except
1081 for the last two fields. They should have the form
1082 @samp{fontset-@var{alias}}.
1084 The fontset has two names, one long and one short. The long name is
1085 @var{fontpattern}. The short name is @samp{fontset-@var{alias}}. You
1086 can refer to the fontset by either name.
1088 The construct @samp{@var{charset}:@var{font}} specifies which font to
1089 use (in this fontset) for one particular character set. Here,
1090 @var{charset} is the name of a character set, and @var{font} is the
1091 font to use for that character set. You can use this construct any
1092 number of times in defining one fontset.
1094 For the other character sets, Emacs chooses a font based on
1095 @var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values
1096 that describe the character set. For the ASCII character font,
1097 @samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}.
1099 In addition, when several consecutive fields are wildcards, Emacs
1100 collapses them into a single wildcard. This is to prevent use of
1101 auto-scaled fonts. Fonts made by scaling larger fonts are not usable
1102 for editing, and scaling a smaller font is not useful because it is
1103 better to use the smaller font in its own size, which Emacs does.
1105 Thus if @var{fontpattern} is this,
1108 -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24
1112 the font specification for ASCII characters would be this:
1115 -*-fixed-medium-r-normal-*-24-*-ISO8859-1
1119 and the font specification for Chinese GB2312 characters would be this:
1122 -*-fixed-medium-r-normal-*-24-*-gb2312*-*
1125 You may not have any Chinese font matching the above font
1126 specification. Most X distributions include only Chinese fonts that
1127 have @samp{song ti} or @samp{fangsong ti} in @var{family} field. In
1128 such a case, @samp{Fontset-@var{n}} can be specified as below:
1131 Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\
1132 chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-*
1136 Then, the font specifications for all but Chinese GB2312 characters have
1137 @samp{fixed} in the @var{family} field, and the font specification for
1138 Chinese GB2312 characters has a wild card @samp{*} in the @var{family}
1141 @findex create-fontset-from-fontset-spec
1142 The function that processes the fontset resource value to create the
1143 fontset is called @code{create-fontset-from-fontset-spec}. You can also
1144 call this function explicitly to create a fontset.
1146 @xref{Font X}, for more information about font naming in X.
1148 @node Undisplayable Characters
1149 @section Undisplayable Characters
1151 Your terminal may be unable to display some non-@sc{ascii}
1152 characters. Most non-windowing terminals can only use a single
1153 character set (use the variable @code{default-terminal-coding-system}
1154 (@pxref{Specify Coding}) to tell Emacs which one); characters which
1155 can't be encoded in that coding system are displayed as @samp{?} by
1158 Windowing terminals can display a broader range of characters, but
1159 you may not have fonts installed for all of them; characters that have
1160 no font appear as a hollow box.
1162 If you use Latin-1 characters but your terminal can't display
1163 Latin-1, you can arrange to display mnemonic @sc{ascii} sequences
1164 instead, e.g.@: @samp{"o} for o-umlaut. Load the library
1165 @file{iso-ascii} to do this.
1167 @vindex latin1-display
1168 If your terminal can display Latin-1, you can display characters
1169 from other European character sets using a mixture of equivalent
1170 Latin-1 characters and @sc{ascii} mnemonics. Use the Custom option
1171 @code{latin1-display} to enable this. The mnemonic @sc{ascii}
1172 sequences mostly correspond to those of the prefix input methods.
1174 @node Single-Byte Character Support
1175 @section Single-byte Character Set Support
1177 @cindex European character sets
1178 @cindex accented characters
1179 @cindex ISO Latin character sets
1180 @cindex Unibyte operation
1181 The ISO 8859 Latin-@var{n} character sets define character codes in
1182 the range 160 to 255 to handle the accented letters and punctuation
1183 needed by various European languages (and some non-European ones).
1184 If you disable multibyte
1185 characters, Emacs can still handle @emph{one} of these character codes
1186 at a time. To specify @emph{which} of these codes to use, invoke
1187 @kbd{M-x set-language-environment} and specify a suitable language
1188 environment such as @samp{Latin-@var{n}}.
1190 For more information about unibyte operation, see @ref{Enabling
1191 Multibyte}. Note particularly that you probably want to ensure that
1192 your initialization files are read as unibyte if they contain non-ASCII
1195 @vindex unibyte-display-via-language-environment
1196 Emacs can also display those characters, provided the terminal or font
1197 in use supports them. This works automatically. Alternatively, if you
1198 are using a window system, Emacs can also display single-byte characters
1199 through fontsets, in effect by displaying the equivalent multibyte
1200 characters according to the current language environment. To request
1201 this, set the variable @code{unibyte-display-via-language-environment}
1202 to a non-@code{nil} value.
1204 @cindex @code{iso-ascii} library
1205 If your terminal does not support display of the Latin-1 character
1206 set, Emacs can display these characters as ASCII sequences which at
1207 least give you a clear idea of what the characters are. To do this,
1208 load the library @code{iso-ascii}. Similar libraries for other
1209 Latin-@var{n} character sets could be implemented, but we don't have
1212 @findex standard-display-8bit
1213 @cindex 8-bit display
1214 Normally non-ISO-8859 characters (between characters 128 and 159
1215 inclusive) are displayed as octal escapes. You can change this for
1216 non-standard ``extended'' versions of ISO-8859 character sets by using the
1217 function @code{standard-display-8bit} in the @code{disp-table} library.
1219 There are several ways you can input single-byte non-ASCII
1225 If your keyboard can generate character codes 128 and up, representing
1226 non-ASCII you can type those character codes directly.
1228 On a windowing terminal, you should not need to do anything special to
1229 use these keys; they should simply work. On a text-only terminal, you
1230 should use the command @code{M-x set-keyboard-coding-system} or the
1231 Custom option @code{keyboard-coding-system} to specify which coding
1232 system your keyboard uses (@pxref{Specify Coding}). Enabling this
1233 feature will probably require you to use @kbd{ESC} to type Meta
1234 characters; however, on a Linux console or in @code{xterm}, you can
1235 arrange for Meta to be converted to @kbd{ESC} and still be able type
1236 8-bit characters present directly on the keyboard or using
1237 @kbd{Compose} or @kbd{AltGr} keys. @xref{User Input}.
1240 You can use an input method for the selected language environment.
1241 @xref{Input Methods}. When you use an input method in a unibyte buffer,
1242 the non-ASCII character you specify with it is converted to unibyte.
1245 @cindex @code{iso-transl} library
1246 @cindex compose character
1247 @cindex dead character
1249 For Latin-1 only, you can use the
1250 key @kbd{C-x 8} as a ``compose character'' prefix for entry of
1251 non-ASCII Latin-1 printing characters. @kbd{C-x 8} is good for
1252 insertion (in the minibuffer as well as other buffers), for searching,
1253 and in any other context where a key sequence is allowed.
1255 @kbd{C-x 8} works by loading the @code{iso-transl} library. Once that
1256 library is loaded, the @key{ALT} modifier key, if you have one, serves
1257 the same purpose as @kbd{C-x 8}; use @key{ALT} together with an accent
1258 character to modify the following letter. In addition, if you have keys
1259 for the Latin-1 ``dead accent characters,'' they too are defined to
1260 compose with the following character, once @code{iso-transl} is loaded.
1261 Use @kbd{C-x 8 C-h} to list the available translations as mnemonic
1265 @cindex @code{iso-acc} library
1266 @cindex ISO Accents mode
1267 @findex iso-accents-mode
1268 @cindex Latin-1, Latin-2 and Latin-3 input mode
1269 For Latin-1, Latin-2 and Latin-3, @kbd{M-x iso-accents-mode} installs
1270 a minor mode which works much like the @code{latin-1-prefix} input
1271 method does not depend on having the input methods installed. This
1272 mode is buffer-local. It can be customized for various languages with
1273 @kbd{M-x iso-accents-customize}.