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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
9952f1f8 | 2 | @c Copyright (C) 1997, 1999, 2000, 2001 Free Software Foundation, Inc. |
6bf7aab6 DL |
3 | @c See file emacs.texi for copying conditions. |
4 | @node International, Major Modes, Frames, Top | |
5 | @chapter International Character Set Support | |
6 | @cindex MULE | |
7 | @cindex international scripts | |
8 | @cindex multibyte characters | |
9 | @cindex encoding of characters | |
10 | ||
cca7bf28 | 11 | @cindex Celtic |
6bf7aab6 | 12 | @cindex Chinese |
fbc164de | 13 | @cindex Cyrillic |
cca7bf28 | 14 | @cindex Czech |
6bf7aab6 DL |
15 | @cindex Devanagari |
16 | @cindex Hindi | |
17 | @cindex Marathi | |
fbc164de | 18 | @cindex Ethiopic |
cca7bf28 | 19 | @cindex German |
6bf7aab6 | 20 | @cindex Greek |
fbc164de | 21 | @cindex Hebrew |
6bf7aab6 DL |
22 | @cindex IPA |
23 | @cindex Japanese | |
24 | @cindex Korean | |
25 | @cindex Lao | |
cca7bf28 EZ |
26 | @cindex Latin |
27 | @cindex Polish | |
28 | @cindex Romanian | |
29 | @cindex Slovak | |
30 | @cindex Slovenian | |
6bf7aab6 DL |
31 | @cindex Thai |
32 | @cindex Tibetan | |
cca7bf28 | 33 | @cindex Turkish |
6bf7aab6 | 34 | @cindex Vietnamese |
732b9cdd GM |
35 | @cindex Dutch |
36 | @cindex Spanish | |
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37 | Emacs supports a wide variety of international character sets, |
38 | including European variants of the Latin alphabet, as well as Chinese, | |
fbc164de PE |
39 | Cyrillic, Devanagari (Hindi and Marathi), Ethiopic, Greek, Hebrew, IPA, |
40 | Japanese, Korean, Lao, Thai, Tibetan, and Vietnamese scripts. These features | |
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41 | have been merged from the modified version of Emacs known as MULE (for |
42 | ``MULti-lingual Enhancement to GNU Emacs'') | |
43 | ||
9d9c2e39 | 44 | Emacs also supports various encodings of these characters used by |
4b40407a | 45 | other internationalized software, such as word processors and mailers. |
9d9c2e39 | 46 | |
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47 | Emacs allows editing text with international characters by supporting |
48 | all the related activities: | |
49 | ||
50 | @itemize @bullet | |
51 | @item | |
76dd3692 EZ |
52 | You can visit files with non-@acronym{ASCII} characters, save non-@acronym{ASCII} text, and |
53 | pass non-@acronym{ASCII} text between Emacs and programs it invokes (such as | |
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54 | compilers, spell-checkers, and mailers). Setting your language |
55 | environment (@pxref{Language Environments}) takes care of setting up the | |
56 | coding systems and other options for a specific language or culture. | |
57 | Alternatively, you can specify how Emacs should encode or decode text | |
58 | for each command; see @ref{Specify Coding}. | |
59 | ||
60 | @item | |
76dd3692 | 61 | You can display non-@acronym{ASCII} characters encoded by the various scripts. |
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62 | This works by using appropriate fonts on X and similar graphics |
63 | displays (@pxref{Defining Fontsets}), and by sending special codes to | |
64 | text-only displays (@pxref{Specify Coding}). If some characters are | |
65 | displayed incorrectly, refer to @ref{Undisplayable Characters}, which | |
66 | describes possible problems and explains how to solve them. | |
67 | ||
68 | @item | |
76dd3692 | 69 | You can insert non-@acronym{ASCII} characters or search for them. To do that, |
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70 | you can specify an input method (@pxref{Select Input Method}) suitable |
71 | for your language, or use the default input method set up when you set | |
72 | your language environment. (Emacs input methods are part of the Leim | |
73 | package, which must be installed for you to be able to use them.) If | |
76dd3692 | 74 | your keyboard can produce non-@acronym{ASCII} characters, you can select an |
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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, | |
579cb67d | 78 | C-x 8}. On X Window systems, your locale should be set to an |
e20b7447 | 79 | appropriate value to make sure Emacs interprets keyboard input |
afcdd7bd | 80 | correctly; see @ref{Language Environments, locales}. |
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81 | @end itemize |
82 | ||
83 | The rest of this chapter describes these issues in detail. | |
84 | ||
6bf7aab6 | 85 | @menu |
cb1fa3f5 | 86 | * International Chars:: Basic concepts of multibyte characters. |
6bf7aab6 DL |
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. | |
60245086 | 99 | * Undisplayable Characters:: When characters don't display. |
521ab838 | 100 | * Single-Byte Character Support:: |
6bf7aab6 DL |
101 | You can pick one European character set |
102 | to use without multibyte characters. | |
52254d1a | 103 | * Charsets:: How Emacs groups its internal character codes. |
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104 | @end menu |
105 | ||
cb1fa3f5 | 106 | @node International Chars |
6bf7aab6 DL |
107 | @section Introduction to International Character Sets |
108 | ||
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109 | The users of international character sets and scripts have established |
110 | many more-or-less standard coding systems for storing files. Emacs | |
111 | internally uses a single multibyte character encoding, so that it can | |
112 | intermix characters from all these scripts in a single buffer or string. | |
76dd3692 | 113 | This encoding represents each non-@acronym{ASCII} character as a sequence of bytes |
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114 | in the range 0200 through 0377. Emacs translates between the multibyte |
115 | character encoding and various other coding systems when reading and | |
116 | writing files, when exchanging data with subprocesses, and (in some | |
117 | cases) in the @kbd{C-q} command (@pxref{Multibyte Conversion}). | |
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118 | |
119 | @kindex C-h h | |
120 | @findex view-hello-file | |
457b792c | 121 | @cindex undisplayable characters |
4b40407a | 122 | @cindex @samp{?} in display |
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123 | The command @kbd{C-h h} (@code{view-hello-file}) displays the file |
124 | @file{etc/HELLO}, which shows how to say ``hello'' in many languages. | |
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125 | This illustrates various scripts. If some characters can't be |
126 | displayed on your terminal, they appear as @samp{?} or as hollow boxes | |
127 | (@pxref{Undisplayable Characters}). | |
128 | ||
129 | Keyboards, even in the countries where these character sets are used, | |
130 | generally don't have keys for all the characters in them. So Emacs | |
131 | supports various @dfn{input methods}, typically one for each script or | |
132 | language, to make it convenient to type them. | |
133 | ||
134 | @kindex C-x RET | |
135 | The prefix key @kbd{C-x @key{RET}} is used for commands that pertain | |
136 | to multibyte characters, coding systems, and input methods. | |
137 | ||
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138 | @node Enabling Multibyte |
139 | @section Enabling Multibyte Characters | |
140 | ||
8561e53a | 141 | @cindex turn multibyte support on or off |
6bf7aab6 DL |
142 | You can enable or disable multibyte character support, either for |
143 | Emacs as a whole, or for a single buffer. When multibyte characters are | |
144 | disabled in a buffer, then each byte in that buffer represents a | |
145 | character, even codes 0200 through 0377. The old features for | |
146 | supporting the European character sets, ISO Latin-1 and ISO Latin-2, | |
147 | work as they did in Emacs 19 and also work for the other ISO 8859 | |
148 | character sets. | |
149 | ||
150 | However, there is no need to turn off multibyte character support to | |
151 | use ISO Latin; the Emacs multibyte character set includes all the | |
152 | characters in these character sets, and Emacs can translate | |
153 | automatically to and from the ISO codes. | |
154 | ||
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155 | By default, Emacs starts in multibyte mode, because that allows you to |
156 | use all the supported languages and scripts without limitations. | |
157 | ||
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158 | To edit a particular file in unibyte representation, visit it using |
159 | @code{find-file-literally}. @xref{Visiting}. To convert a buffer in | |
160 | multibyte representation into a single-byte representation of the same | |
161 | characters, the easiest way is to save the contents in a file, kill the | |
162 | buffer, and find the file again with @code{find-file-literally}. You | |
163 | can also use @kbd{C-x @key{RET} c} | |
164 | (@code{universal-coding-system-argument}) and specify @samp{raw-text} as | |
165 | the coding system with which to find or save a file. @xref{Specify | |
166 | Coding}. Finding a file as @samp{raw-text} doesn't disable format | |
167 | conversion, uncompression and auto mode selection as | |
168 | @code{find-file-literally} does. | |
169 | ||
170 | @vindex enable-multibyte-characters | |
171 | @vindex default-enable-multibyte-characters | |
172 | To turn off multibyte character support by default, start Emacs with | |
173 | the @samp{--unibyte} option (@pxref{Initial Options}), or set the | |
60a96371 | 174 | environment variable @env{EMACS_UNIBYTE}. You can also customize |
6bf7aab6 | 175 | @code{enable-multibyte-characters} or, equivalently, directly set the |
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176 | variable @code{default-enable-multibyte-characters} to @code{nil} in |
177 | your init file to have basically the same effect as @samp{--unibyte}. | |
178 | ||
179 | @findex toggle-enable-multibyte-characters | |
180 | To convert a unibyte session to a multibyte session, set | |
181 | @code{default-enable-multibyte-characters} to @code{t}. Buffers which | |
182 | were created in the unibyte session before you turn on multibyte support | |
183 | will stay unibyte. You can turn on multibyte support in a specific | |
184 | buffer by invoking the command @code{toggle-enable-multibyte-characters} | |
185 | in that buffer. | |
6bf7aab6 | 186 | |
576f17ff EZ |
187 | @cindex Lisp files, and multibyte operation |
188 | @cindex multibyte operation, and Lisp files | |
189 | @cindex unibyte operation, and Lisp files | |
76dd3692 EZ |
190 | @cindex init file, and non-@acronym{ASCII} characters |
191 | @cindex environment variables, and non-@acronym{ASCII} characters | |
4b40407a RS |
192 | With @samp{--unibyte}, multibyte strings are not created during |
193 | initialization from the values of environment variables, | |
76dd3692 | 194 | @file{/etc/passwd} entries etc.@: that contain non-@acronym{ASCII} 8-bit |
4b40407a RS |
195 | characters. |
196 | ||
197 | Emacs normally loads Lisp files as multibyte, regardless of whether | |
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198 | you used @samp{--unibyte}. This includes the Emacs initialization file, |
199 | @file{.emacs}, and the initialization files of Emacs packages such as | |
200 | Gnus. However, you can specify unibyte loading for a particular Lisp | |
201 | file, by putting @w{@samp{-*-unibyte: t;-*-}} in a comment on the first | |
202 | line (@pxref{File Variables}). Then that file is always loaded as | |
203 | unibyte text, even if you did not start Emacs with @samp{--unibyte}. | |
204 | The motivation for these conventions is that it is more reliable to | |
205 | always load any particular Lisp file in the same way. However, you can | |
206 | load a Lisp file as unibyte, on any one occasion, by typing @kbd{C-x | |
12de6e26 | 207 | @key{RET} c raw-text @key{RET}} immediately before loading it. |
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208 | |
209 | The mode line indicates whether multibyte character support is enabled | |
210 | in the current buffer. If it is, there are two or more characters (most | |
211 | often two dashes) before the colon near the beginning of the mode line. | |
212 | When multibyte characters are not enabled, just one dash precedes the | |
213 | colon. | |
214 | ||
215 | @node Language Environments | |
216 | @section Language Environments | |
217 | @cindex language environments | |
218 | ||
219 | All supported character sets are supported in Emacs buffers whenever | |
220 | multibyte characters are enabled; there is no need to select a | |
221 | particular language in order to display its characters in an Emacs | |
222 | buffer. However, it is important to select a @dfn{language environment} | |
223 | in order to set various defaults. The language environment really | |
224 | represents a choice of preferred script (more or less) rather than a | |
225 | choice of language. | |
226 | ||
227 | The language environment controls which coding systems to recognize | |
228 | when reading text (@pxref{Recognize Coding}). This applies to files, | |
229 | incoming mail, netnews, and any other text you read into Emacs. It may | |
230 | also specify the default coding system to use when you create a file. | |
231 | Each language environment also specifies a default input method. | |
232 | ||
233 | @findex set-language-environment | |
fbc164de | 234 | @vindex current-language-environment |
65b4fec5 | 235 | To select a language environment, you can customize the variable |
fbc164de | 236 | @code{current-language-environment} or use the command @kbd{M-x |
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237 | set-language-environment}. It makes no difference which buffer is |
238 | current when you use this command, because the effects apply globally to | |
239 | the Emacs session. The supported language environments include: | |
240 | ||
60245086 | 241 | @cindex Euro sign |
4c2b3186 | 242 | @cindex UTF-8 |
6bf7aab6 | 243 | @quotation |
fbc164de | 244 | Chinese-BIG5, Chinese-CNS, Chinese-GB, Cyrillic-ALT, Cyrillic-ISO, |
ea6f077a RS |
245 | Cyrillic-KOI8, Czech, Devanagari, Dutch, English, Ethiopic, German, |
246 | Greek, Hebrew, IPA, Japanese, Korean, Lao, Latin-1, Latin-2, Latin-3, | |
247 | Latin-4, Latin-5, Latin-8 (Celtic), Latin-9 (updated Latin-1, with the | |
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248 | Euro sign), Polish, Romanian, Slovak, Slovenian, Spanish, Thai, Tibetan, |
249 | Turkish, UTF-8 (for a setup which prefers Unicode characters and files | |
250 | encoded in UTF-8), and Vietnamese. | |
6bf7aab6 DL |
251 | @end quotation |
252 | ||
4b40407a | 253 | @cindex fonts for various scripts |
0d314165 | 254 | @cindex Intlfonts package, installation |
4b40407a RS |
255 | To display the script(s) used by your language environment on a |
256 | graphical display, you need to have a suitable font. If some of the | |
257 | characters appear as empty boxes, you should install the GNU Intlfonts | |
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258 | package, which includes fonts for all supported scripts.@footnote{If |
259 | you run Emacs on X, you need to inform the X server about the location | |
260 | of the newly installed fonts with the following commands: | |
261 | ||
262 | @example | |
263 | xset fp+ /usr/local/share/emacs/fonts | |
264 | xset fp rehash | |
265 | @end example | |
266 | } | |
4b40407a | 267 | @xref{Fontsets}, for more details about setting up your fonts. |
9aeaea42 | 268 | |
fbc164de PE |
269 | @findex set-locale-environment |
270 | @vindex locale-language-names | |
271 | @vindex locale-charset-language-names | |
60245086 | 272 | @cindex locales |
80f0ce09 EZ |
273 | Some operating systems let you specify the character-set locale you |
274 | are using by setting the locale environment variables @env{LC_ALL}, | |
275 | @env{LC_CTYPE}, or @env{LANG}.@footnote{If more than one of these is | |
276 | set, the first one that is nonempty specifies your locale for this | |
277 | purpose.} During startup, Emacs looks up your character-set locale's | |
278 | name in the system locale alias table, matches its canonical name | |
279 | against entries in the value of the variables | |
280 | @code{locale-charset-language-names} and @code{locale-language-names}, | |
281 | and selects the corresponding language environment if a match is found. | |
282 | (The former variable overrides the latter.) It also adjusts the display | |
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283 | table and terminal coding system, the locale coding system, the |
284 | preferred coding system as needed for the locale, and---last but not | |
76dd3692 | 285 | least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard. |
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286 | |
287 | If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG} | |
288 | environment variables while running Emacs, you may want to invoke the | |
a9749dab | 289 | @code{set-locale-environment} function afterwards to readjust the |
4b40407a | 290 | language environment from the new locale. |
fa71a532 | 291 | |
fbc164de PE |
292 | @vindex locale-preferred-coding-systems |
293 | The @code{set-locale-environment} function normally uses the preferred | |
294 | coding system established by the language environment to decode system | |
295 | messages. But if your locale matches an entry in the variable | |
296 | @code{locale-preferred-coding-systems}, Emacs uses the corresponding | |
297 | coding system instead. For example, if the locale @samp{ja_JP.PCK} | |
298 | matches @code{japanese-shift-jis} in | |
299 | @code{locale-preferred-coding-systems}, Emacs uses that encoding even | |
300 | though it might normally use @code{japanese-iso-8bit}. | |
301 | ||
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302 | You can override the language environment chosen at startup with |
303 | explicit use of the command @code{set-language-environment}, or with | |
304 | customization of @code{current-language-environment} in your init | |
305 | file. | |
6bf7aab6 DL |
306 | |
307 | @kindex C-h L | |
308 | @findex describe-language-environment | |
309 | To display information about the effects of a certain language | |
310 | environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env} | |
311 | @key{RET}} (@code{describe-language-environment}). This tells you which | |
312 | languages this language environment is useful for, and lists the | |
313 | character sets, coding systems, and input methods that go with it. It | |
314 | also shows some sample text to illustrate scripts used in this language | |
315 | environment. By default, this command describes the chosen language | |
316 | environment. | |
317 | ||
318 | @vindex set-language-environment-hook | |
319 | You can customize any language environment with the normal hook | |
320 | @code{set-language-environment-hook}. The command | |
321 | @code{set-language-environment} runs that hook after setting up the new | |
322 | language environment. The hook functions can test for a specific | |
323 | language environment by checking the variable | |
0d314165 EZ |
324 | @code{current-language-environment}. This hook is where you should |
325 | put non-default settings for specific language environment, such as | |
326 | coding systems for keyboard input and terminal output, the default | |
327 | input method, etc. | |
6bf7aab6 DL |
328 | |
329 | @vindex exit-language-environment-hook | |
330 | Before it starts to set up the new language environment, | |
331 | @code{set-language-environment} first runs the hook | |
332 | @code{exit-language-environment-hook}. This hook is useful for undoing | |
333 | customizations that were made with @code{set-language-environment-hook}. | |
334 | For instance, if you set up a special key binding in a specific language | |
335 | environment using @code{set-language-environment-hook}, you should set | |
336 | up @code{exit-language-environment-hook} to restore the normal binding | |
337 | for that key. | |
338 | ||
339 | @node Input Methods | |
340 | @section Input Methods | |
341 | ||
342 | @cindex input methods | |
343 | An @dfn{input method} is a kind of character conversion designed | |
344 | specifically for interactive input. In Emacs, typically each language | |
345 | has its own input method; sometimes several languages which use the same | |
346 | characters can share one input method. A few languages support several | |
347 | input methods. | |
348 | ||
76dd3692 | 349 | The simplest kind of input method works by mapping @acronym{ASCII} letters |
a9749dab | 350 | into another alphabet; this allows you to use one other alphabet |
76dd3692 | 351 | instead of @acronym{ASCII}. The Greek and Russian input methods |
a9749dab | 352 | work this way. |
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353 | |
354 | A more powerful technique is composition: converting sequences of | |
355 | characters into one letter. Many European input methods use composition | |
76dd3692 | 356 | to produce a single non-@acronym{ASCII} letter from a sequence that consists of a |
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357 | letter followed by accent characters (or vice versa). For example, some |
358 | methods convert the sequence @kbd{a'} into a single accented letter. | |
359 | These input methods have no special commands of their own; all they do | |
360 | is compose sequences of printing characters. | |
361 | ||
362 | The input methods for syllabic scripts typically use mapping followed | |
363 | by composition. The input methods for Thai and Korean work this way. | |
364 | First, letters are mapped into symbols for particular sounds or tone | |
365 | marks; then, sequences of these which make up a whole syllable are | |
366 | mapped into one syllable sign. | |
367 | ||
368 | Chinese and Japanese require more complex methods. In Chinese input | |
369 | methods, first you enter the phonetic spelling of a Chinese word (in | |
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370 | input method @code{chinese-py}, among others), or a sequence of |
371 | portions of the character (input methods @code{chinese-4corner} and | |
a9749dab RS |
372 | @code{chinese-sw}, and others). One input sequence typically |
373 | corresponds to many possible Chinese characters. You select the one | |
27b81dec EZ |
374 | you mean using keys such as @kbd{C-f}, @kbd{C-b}, @kbd{C-n}, |
375 | @kbd{C-p}, and digits, which have special meanings in this situation. | |
376 | ||
377 | The possible characters are conceptually arranged in several rows, | |
378 | with each row holding up to 10 alternatives. Normally, Emacs displays | |
379 | just one row at a time, in the echo area; @code{(@var{i}/@var{j})} | |
380 | appears at the beginning, to indicate that this is the @var{i}th row | |
381 | out of a total of @var{j} rows. Type @kbd{C-n} or @kbd{C-p} to | |
382 | display the next row or the previous row. | |
383 | ||
384 | Type @kbd{C-f} and @kbd{C-b} to move forward and backward among | |
385 | the alternatives in the current row. As you do this, Emacs highlights | |
386 | the current alternative with a special color; type @code{C-@key{SPC}} | |
387 | to select the current alternative and use it as input. The | |
388 | alternatives in the row are also numbered; the number appears before | |
389 | the alternative. Typing a digit @var{n} selects the @var{n}th | |
390 | alternative of the current row and uses it as input. | |
391 | ||
392 | @key{TAB} in these Chinese input methods displays a buffer showing | |
393 | all the possible characters at once; then clicking @kbd{Mouse-2} on | |
394 | one of them selects that alternative. The keys @kbd{C-f}, @kbd{C-b}, | |
a9749dab RS |
395 | @kbd{C-n}, @kbd{C-p}, and digits continue to work as usual, but they |
396 | do the highlighting in the buffer showing the possible characters, | |
397 | rather than in the echo area. | |
27b81dec EZ |
398 | |
399 | In Japanese input methods, first you input a whole word using | |
400 | phonetic spelling; then, after the word is in the buffer, Emacs | |
401 | converts it into one or more characters using a large dictionary. One | |
402 | phonetic spelling corresponds to a number of different Japanese words; | |
403 | to select one of them, use @kbd{C-n} and @kbd{C-p} to cycle through | |
6bf7aab6 DL |
404 | the alternatives. |
405 | ||
406 | Sometimes it is useful to cut off input method processing so that the | |
407 | characters you have just entered will not combine with subsequent | |
408 | characters. For example, in input method @code{latin-1-postfix}, the | |
409 | sequence @kbd{e '} combines to form an @samp{e} with an accent. What if | |
410 | you want to enter them as separate characters? | |
411 | ||
12de6e26 | 412 | One way is to type the accent twice; this is a special feature for |
6bf7aab6 DL |
413 | entering the separate letter and accent. For example, @kbd{e ' '} gives |
414 | you the two characters @samp{e'}. Another way is to type another letter | |
415 | after the @kbd{e}---something that won't combine with that---and | |
416 | immediately delete it. For example, you could type @kbd{e e @key{DEL} | |
417 | '} to get separate @samp{e} and @samp{'}. | |
418 | ||
419 | Another method, more general but not quite as easy to type, is to use | |
420 | @kbd{C-\ C-\} between two characters to stop them from combining. This | |
421 | is the command @kbd{C-\} (@code{toggle-input-method}) used twice. | |
422 | @ifinfo | |
423 | @xref{Select Input Method}. | |
424 | @end ifinfo | |
425 | ||
0d314165 | 426 | @cindex incremental search, input method interference |
6bf7aab6 DL |
427 | @kbd{C-\ C-\} is especially useful inside an incremental search, |
428 | because it stops waiting for more characters to combine, and starts | |
429 | searching for what you have already entered. | |
430 | ||
431 | @vindex input-method-verbose-flag | |
432 | @vindex input-method-highlight-flag | |
433 | The variables @code{input-method-highlight-flag} and | |
ea6f077a RS |
434 | @code{input-method-verbose-flag} control how input methods explain |
435 | what is happening. If @code{input-method-highlight-flag} is | |
436 | non-@code{nil}, the partial sequence is highlighted in the buffer (for | |
437 | most input methods---some disable this feature). If | |
438 | @code{input-method-verbose-flag} is non-@code{nil}, the list of | |
439 | possible characters to type next is displayed in the echo area (but | |
440 | not when you are in the minibuffer). | |
6bf7aab6 | 441 | |
98c271eb | 442 | @cindex Leim package |
4b40407a RS |
443 | Input methods are implemented in the separate Leim package: they are |
444 | available only if the system administrator used Leim when building | |
445 | Emacs. If Emacs was built without Leim, you will find that no input | |
446 | methods are defined. | |
98c271eb | 447 | |
6bf7aab6 DL |
448 | @node Select Input Method |
449 | @section Selecting an Input Method | |
450 | ||
451 | @table @kbd | |
452 | @item C-\ | |
453 | Enable or disable use of the selected input method. | |
454 | ||
455 | @item C-x @key{RET} C-\ @var{method} @key{RET} | |
456 | Select a new input method for the current buffer. | |
457 | ||
458 | @item C-h I @var{method} @key{RET} | |
459 | @itemx C-h C-\ @var{method} @key{RET} | |
460 | @findex describe-input-method | |
461 | @kindex C-h I | |
462 | @kindex C-h C-\ | |
463 | Describe the input method @var{method} (@code{describe-input-method}). | |
67320f8d DL |
464 | By default, it describes the current input method (if any). This |
465 | description should give you the full details of how to use any | |
a39fb83d | 466 | particular input method. |
6bf7aab6 DL |
467 | |
468 | @item M-x list-input-methods | |
469 | Display a list of all the supported input methods. | |
470 | @end table | |
471 | ||
472 | @findex set-input-method | |
473 | @vindex current-input-method | |
474 | @kindex C-x RET C-\ | |
475 | To choose an input method for the current buffer, use @kbd{C-x | |
476 | @key{RET} C-\} (@code{set-input-method}). This command reads the | |
12de6e26 | 477 | input method name from the minibuffer; the name normally starts with the |
6bf7aab6 DL |
478 | language environment that it is meant to be used with. The variable |
479 | @code{current-input-method} records which input method is selected. | |
177c0ea7 | 480 | |
6bf7aab6 DL |
481 | @findex toggle-input-method |
482 | @kindex C-\ | |
76dd3692 EZ |
483 | Input methods use various sequences of @acronym{ASCII} characters to stand for |
484 | non-@acronym{ASCII} characters. Sometimes it is useful to turn off the input | |
6bf7aab6 DL |
485 | method temporarily. To do this, type @kbd{C-\} |
486 | (@code{toggle-input-method}). To reenable the input method, type | |
487 | @kbd{C-\} again. | |
488 | ||
489 | If you type @kbd{C-\} and you have not yet selected an input method, | |
490 | it prompts for you to specify one. This has the same effect as using | |
491 | @kbd{C-x @key{RET} C-\} to specify an input method. | |
492 | ||
dbee590b EZ |
493 | When invoked with a numeric argument, as in @kbd{C-u C-\}, |
494 | @code{toggle-input-method} always prompts you for an input method, | |
495 | suggesting the most recently selected one as the default. | |
496 | ||
6bf7aab6 DL |
497 | @vindex default-input-method |
498 | Selecting a language environment specifies a default input method for | |
499 | use in various buffers. When you have a default input method, you can | |
500 | select it in the current buffer by typing @kbd{C-\}. The variable | |
501 | @code{default-input-method} specifies the default input method | |
502 | (@code{nil} means there is none). | |
503 | ||
0d314165 EZ |
504 | In some language environments, which support several different input |
505 | methods, you might want to use an input method different from the | |
506 | default chosen by @code{set-language-environment}. You can instruct | |
507 | Emacs to select a different default input method for a certain | |
ea6f077a | 508 | language environment, if you wish, by using |
0d314165 EZ |
509 | @code{set-language-environment-hook} (@pxref{Language Environments, |
510 | set-language-environment-hook}). For example: | |
511 | ||
512 | @lisp | |
513 | (defun my-chinese-setup () | |
514 | "Set up my private Chinese environment." | |
515 | (if (equal current-language-environment "Chinese-GB") | |
516 | (setq default-input-method "chinese-tonepy"))) | |
517 | (add-hook 'set-language-environment-hook 'my-chinese-setup) | |
518 | @end lisp | |
519 | ||
520 | @noindent | |
521 | This sets the default input method to be @code{chinese-tonepy} | |
522 | whenever you choose a Chinese-GB language environment. | |
523 | ||
6bf7aab6 DL |
524 | @findex quail-set-keyboard-layout |
525 | Some input methods for alphabetic scripts work by (in effect) | |
526 | remapping the keyboard to emulate various keyboard layouts commonly used | |
527 | for those scripts. How to do this remapping properly depends on your | |
528 | actual keyboard layout. To specify which layout your keyboard has, use | |
529 | the command @kbd{M-x quail-set-keyboard-layout}. | |
530 | ||
531 | @findex list-input-methods | |
532 | To display a list of all the supported input methods, type @kbd{M-x | |
533 | list-input-methods}. The list gives information about each input | |
534 | method, including the string that stands for it in the mode line. | |
535 | ||
536 | @node Multibyte Conversion | |
76dd3692 | 537 | @section Unibyte and Multibyte Non-@acronym{ASCII} characters |
6bf7aab6 DL |
538 | |
539 | When multibyte characters are enabled, character codes 0240 (octal) | |
540 | through 0377 (octal) are not really legitimate in the buffer. The valid | |
76dd3692 | 541 | non-@acronym{ASCII} printing characters have codes that start from 0400. |
6bf7aab6 | 542 | |
4b40407a RS |
543 | If you type a self-inserting character in the range 0240 through |
544 | 0377, or if you use @kbd{C-q} to insert one, Emacs assumes you | |
545 | intended to use one of the ISO Latin-@var{n} character sets, and | |
546 | converts it to the Emacs code representing that Latin-@var{n} | |
547 | character. You select @emph{which} ISO Latin character set to use | |
548 | through your choice of language environment | |
6bf7aab6 DL |
549 | @iftex |
550 | (see above). | |
551 | @end iftex | |
552 | @ifinfo | |
553 | (@pxref{Language Environments}). | |
554 | @end ifinfo | |
555 | If you do not specify a choice, the default is Latin-1. | |
556 | ||
4b40407a RS |
557 | If you insert a character in the range 0200 through 0237, which |
558 | forms the @code{eight-bit-control} character set, it is inserted | |
60245086 DL |
559 | literally. You should normally avoid doing this since buffers |
560 | containing such characters have to be written out in either the | |
4b40407a RS |
561 | @code{emacs-mule} or @code{raw-text} coding system, which is usually |
562 | not what you want. | |
6bf7aab6 DL |
563 | |
564 | @node Coding Systems | |
565 | @section Coding Systems | |
566 | @cindex coding systems | |
567 | ||
568 | Users of various languages have established many more-or-less standard | |
569 | coding systems for representing them. Emacs does not use these coding | |
570 | systems internally; instead, it converts from various coding systems to | |
571 | its own system when reading data, and converts the internal coding | |
572 | system to other coding systems when writing data. Conversion is | |
573 | possible in reading or writing files, in sending or receiving from the | |
574 | terminal, and in exchanging data with subprocesses. | |
575 | ||
576 | Emacs assigns a name to each coding system. Most coding systems are | |
577 | used for one language, and the name of the coding system starts with the | |
578 | language name. Some coding systems are used for several languages; | |
579 | their names usually start with @samp{iso}. There are also special | |
580 | coding systems @code{no-conversion}, @code{raw-text} and | |
581 | @code{emacs-mule} which do not convert printing characters at all. | |
582 | ||
8561e53a | 583 | @cindex international files from DOS/Windows systems |
9d9c2e39 EZ |
584 | A special class of coding systems, collectively known as |
585 | @dfn{codepages}, is designed to support text encoded by MS-Windows and | |
586 | MS-DOS software. To use any of these systems, you need to create it | |
8561e53a EZ |
587 | with @kbd{M-x codepage-setup}. @xref{MS-DOS and MULE}. After |
588 | creating the coding system for the codepage, you can use it as any | |
589 | other coding system. For example, to visit a file encoded in codepage | |
590 | 850, type @kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename} | |
591 | @key{RET}}. | |
9d9c2e39 | 592 | |
76dd3692 | 593 | In addition to converting various representations of non-@acronym{ASCII} |
6bf7aab6 DL |
594 | characters, a coding system can perform end-of-line conversion. Emacs |
595 | handles three different conventions for how to separate lines in a file: | |
596 | newline, carriage-return linefeed, and just carriage-return. | |
597 | ||
598 | @table @kbd | |
599 | @item C-h C @var{coding} @key{RET} | |
600 | Describe coding system @var{coding}. | |
601 | ||
602 | @item C-h C @key{RET} | |
603 | Describe the coding systems currently in use. | |
604 | ||
605 | @item M-x list-coding-systems | |
606 | Display a list of all the supported coding systems. | |
607 | @end table | |
608 | ||
609 | @kindex C-h C | |
610 | @findex describe-coding-system | |
611 | The command @kbd{C-h C} (@code{describe-coding-system}) displays | |
612 | information about particular coding systems. You can specify a coding | |
12de6e26 | 613 | system name as the argument; alternatively, with an empty argument, it |
6bf7aab6 DL |
614 | describes the coding systems currently selected for various purposes, |
615 | both in the current buffer and as the defaults, and the priority list | |
616 | for recognizing coding systems (@pxref{Recognize Coding}). | |
617 | ||
618 | @findex list-coding-systems | |
619 | To display a list of all the supported coding systems, type @kbd{M-x | |
620 | list-coding-systems}. The list gives information about each coding | |
621 | system, including the letter that stands for it in the mode line | |
622 | (@pxref{Mode Line}). | |
623 | ||
624 | @cindex end-of-line conversion | |
625 | @cindex MS-DOS end-of-line conversion | |
626 | @cindex Macintosh end-of-line conversion | |
627 | Each of the coding systems that appear in this list---except for | |
628 | @code{no-conversion}, which means no conversion of any kind---specifies | |
629 | how and whether to convert printing characters, but leaves the choice of | |
630 | end-of-line conversion to be decided based on the contents of each file. | |
631 | For example, if the file appears to use the sequence carriage-return | |
632 | linefeed to separate lines, DOS end-of-line conversion will be used. | |
633 | ||
634 | Each of the listed coding systems has three variants which specify | |
635 | exactly what to do for end-of-line conversion: | |
636 | ||
637 | @table @code | |
638 | @item @dots{}-unix | |
639 | Don't do any end-of-line conversion; assume the file uses | |
640 | newline to separate lines. (This is the convention normally used | |
641 | on Unix and GNU systems.) | |
642 | ||
643 | @item @dots{}-dos | |
644 | Assume the file uses carriage-return linefeed to separate lines, and do | |
645 | the appropriate conversion. (This is the convention normally used on | |
2684ed46 | 646 | Microsoft systems.@footnote{It is also specified for MIME @samp{text/*} |
6bf7aab6 DL |
647 | bodies and in other network transport contexts. It is different |
648 | from the SGML reference syntax record-start/record-end format which | |
649 | Emacs doesn't support directly.}) | |
650 | ||
651 | @item @dots{}-mac | |
652 | Assume the file uses carriage-return to separate lines, and do the | |
653 | appropriate conversion. (This is the convention normally used on the | |
654 | Macintosh system.) | |
655 | @end table | |
656 | ||
657 | These variant coding systems are omitted from the | |
658 | @code{list-coding-systems} display for brevity, since they are entirely | |
659 | predictable. For example, the coding system @code{iso-latin-1} has | |
660 | variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and | |
661 | @code{iso-latin-1-mac}. | |
662 | ||
663 | The coding system @code{raw-text} is good for a file which is mainly | |
76dd3692 EZ |
664 | @acronym{ASCII} text, but may contain byte values above 127 which are not meant to |
665 | encode non-@acronym{ASCII} characters. With @code{raw-text}, Emacs copies those | |
6bf7aab6 DL |
666 | byte values unchanged, and sets @code{enable-multibyte-characters} to |
667 | @code{nil} in the current buffer so that they will be interpreted | |
668 | properly. @code{raw-text} handles end-of-line conversion in the usual | |
669 | way, based on the data encountered, and has the usual three variants to | |
670 | specify the kind of end-of-line conversion to use. | |
671 | ||
672 | In contrast, the coding system @code{no-conversion} specifies no | |
76dd3692 | 673 | character code conversion at all---none for non-@acronym{ASCII} byte values and |
6bf7aab6 DL |
674 | none for end of line. This is useful for reading or writing binary |
675 | files, tar files, and other files that must be examined verbatim. It, | |
676 | too, sets @code{enable-multibyte-characters} to @code{nil}. | |
677 | ||
678 | The easiest way to edit a file with no conversion of any kind is with | |
679 | the @kbd{M-x find-file-literally} command. This uses | |
680 | @code{no-conversion}, and also suppresses other Emacs features that | |
681 | might convert the file contents before you see them. @xref{Visiting}. | |
682 | ||
683 | The coding system @code{emacs-mule} means that the file contains | |
76dd3692 | 684 | non-@acronym{ASCII} characters stored with the internal Emacs encoding. It |
6bf7aab6 DL |
685 | handles end-of-line conversion based on the data encountered, and has |
686 | the usual three variants to specify the kind of end-of-line conversion. | |
687 | ||
688 | @node Recognize Coding | |
689 | @section Recognizing Coding Systems | |
690 | ||
8561e53a EZ |
691 | Emacs tries to recognize which coding system to use for a given text |
692 | as an integral part of reading that text. (This applies to files | |
693 | being read, output from subprocesses, text from X selections, etc.) | |
694 | Emacs can select the right coding system automatically most of the | |
695 | time---once you have specified your preferences. | |
6bf7aab6 DL |
696 | |
697 | Some coding systems can be recognized or distinguished by which byte | |
698 | sequences appear in the data. However, there are coding systems that | |
699 | cannot be distinguished, not even potentially. For example, there is no | |
700 | way to distinguish between Latin-1 and Latin-2; they use the same byte | |
701 | values with different meanings. | |
702 | ||
703 | Emacs handles this situation by means of a priority list of coding | |
704 | systems. Whenever Emacs reads a file, if you do not specify the coding | |
705 | system to use, Emacs checks the data against each coding system, | |
706 | starting with the first in priority and working down the list, until it | |
707 | finds a coding system that fits the data. Then it converts the file | |
708 | contents assuming that they are represented in this coding system. | |
709 | ||
710 | The priority list of coding systems depends on the selected language | |
711 | environment (@pxref{Language Environments}). For example, if you use | |
712 | French, you probably want Emacs to prefer Latin-1 to Latin-2; if you use | |
713 | Czech, you probably want Latin-2 to be preferred. This is one of the | |
714 | reasons to specify a language environment. | |
715 | ||
716 | @findex prefer-coding-system | |
65b4fec5 RS |
717 | However, you can alter the coding system priority list in detail |
718 | with the command @kbd{M-x prefer-coding-system}. This command reads | |
719 | the name of a coding system from the minibuffer, and adds it to the | |
720 | front of the priority list, so that it is preferred to all others. If | |
721 | you use this command several times, each use adds one element to the | |
722 | front of the priority list. | |
6bf7aab6 DL |
723 | |
724 | If you use a coding system that specifies the end-of-line conversion | |
12de6e26 | 725 | type, such as @code{iso-8859-1-dos}, what this means is that Emacs |
6bf7aab6 | 726 | should attempt to recognize @code{iso-8859-1} with priority, and should |
a9749dab | 727 | use DOS end-of-line conversion when it does recognize @code{iso-8859-1}. |
6bf7aab6 DL |
728 | |
729 | @vindex file-coding-system-alist | |
730 | Sometimes a file name indicates which coding system to use for the | |
731 | file. The variable @code{file-coding-system-alist} specifies this | |
732 | correspondence. There is a special function | |
733 | @code{modify-coding-system-alist} for adding elements to this list. For | |
734 | example, to read and write all @samp{.txt} files using the coding system | |
735 | @code{china-iso-8bit}, you can execute this Lisp expression: | |
736 | ||
737 | @smallexample | |
738 | (modify-coding-system-alist 'file "\\.txt\\'" 'china-iso-8bit) | |
739 | @end smallexample | |
740 | ||
741 | @noindent | |
742 | The first argument should be @code{file}, the second argument should be | |
743 | a regular expression that determines which files this applies to, and | |
744 | the third argument says which coding system to use for these files. | |
745 | ||
746 | @vindex inhibit-eol-conversion | |
5be757c3 | 747 | @cindex DOS-style end-of-line display |
6bf7aab6 DL |
748 | Emacs recognizes which kind of end-of-line conversion to use based on |
749 | the contents of the file: if it sees only carriage-returns, or only | |
750 | carriage-return linefeed sequences, then it chooses the end-of-line | |
751 | conversion accordingly. You can inhibit the automatic use of | |
752 | end-of-line conversion by setting the variable @code{inhibit-eol-conversion} | |
0d314165 EZ |
753 | to non-@code{nil}. If you do that, DOS-style files will be displayed |
754 | with the @samp{^M} characters visible in the buffer; some people | |
755 | prefer this to the more subtle @samp{(DOS)} end-of-line type | |
756 | indication near the left edge of the mode line (@pxref{Mode Line, | |
1deddb56 | 757 | eol-mnemonic}). |
6bf7aab6 | 758 | |
5be757c3 EZ |
759 | @vindex inhibit-iso-escape-detection |
760 | @cindex escape sequences in files | |
761 | By default, the automatic detection of coding system is sensitive to | |
762 | escape sequences. If Emacs sees a sequence of characters that begin | |
4b40407a RS |
763 | with an escape character, and the sequence is valid as an ISO-2022 |
764 | code, that tells Emacs to use one of the ISO-2022 encodings to decode | |
765 | the file. | |
5be757c3 | 766 | |
4b40407a RS |
767 | However, there may be cases that you want to read escape sequences |
768 | in a file as is. In such a case, you can set the variable | |
5be757c3 | 769 | @code{inhibit-iso-escape-detection} to non-@code{nil}. Then the code |
4b40407a RS |
770 | detection ignores any escape sequences, and never uses an ISO-2022 |
771 | encoding. The result is that all escape sequences become visible in | |
772 | the buffer. | |
5be757c3 EZ |
773 | |
774 | The default value of @code{inhibit-iso-escape-detection} is | |
4b40407a RS |
775 | @code{nil}. We recommend that you not change it permanently, only for |
776 | one specific operation. That's because many Emacs Lisp source files | |
76dd3692 | 777 | in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the |
12de6e26 | 778 | coding system @code{iso-2022-7bit}, and they won't be |
4b40407a RS |
779 | decoded correctly when you visit those files if you suppress the |
780 | escape sequence detection. | |
5be757c3 | 781 | |
6bf7aab6 DL |
782 | @vindex coding |
783 | You can specify the coding system for a particular file using the | |
12de6e26 EZ |
784 | @w{@samp{-*-@dots{}-*-}} construct at the beginning of a file, or a |
785 | local variables list at the end (@pxref{File Variables}). You do this | |
786 | by defining a value for the ``variable'' named @code{coding}. Emacs | |
787 | does not really have a variable @code{coding}; instead of setting a | |
a9749dab | 788 | variable, this uses the specified coding system for the file. For |
12de6e26 | 789 | example, @samp{-*-mode: C; coding: latin-1;-*-} specifies use of the |
a9749dab | 790 | Latin-1 coding system, as well as C mode. When you specify the coding |
12de6e26 EZ |
791 | explicitly in the file, that overrides |
792 | @code{file-coding-system-alist}. | |
6bf7aab6 DL |
793 | |
794 | @vindex auto-coding-alist | |
9952f1f8 | 795 | @vindex auto-coding-regexp-alist |
1d83df13 CW |
796 | @vindex auto-coding-functions |
797 | The variables @code{auto-coding-alist}, | |
798 | @code{auto-coding-regexp-alist} and @code{auto-coding-functions} are | |
799 | the strongest way to specify the coding system for certain patterns of | |
800 | file names, or for files containing certain patterns; these variables | |
801 | even override @samp{-*-coding:-*-} tags in the file itself. Emacs | |
802 | uses @code{auto-coding-alist} for tar and archive files, to prevent it | |
9952f1f8 GM |
803 | from being confused by a @samp{-*-coding:-*-} tag in a member of the |
804 | archive and thinking it applies to the archive file as a whole. | |
805 | Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that | |
1d83df13 CW |
806 | RMAIL files, whose names in general don't match any particular |
807 | pattern, are decoded correctly. One of the builtin | |
808 | @code{auto-coding-functions} detects the encoding for XML files. | |
6bf7aab6 | 809 | |
8561e53a EZ |
810 | If Emacs recognizes the encoding of a file incorrectly, you can |
811 | reread the file using the correct coding system by typing @kbd{C-x | |
812 | @key{RET} c @var{coding-system} @key{RET} M-x revert-buffer | |
5336b0e0 RS |
813 | @key{RET}}. To see what coding system Emacs actually used to decode |
814 | the file, look at the coding system mnemonic letter near the left edge | |
815 | of the mode line (@pxref{Mode Line}), or type @kbd{C-h C @key{RET}}. | |
8561e53a | 816 | |
ba2cf799 RS |
817 | @findex unify-8859-on-decoding-mode |
818 | The command @code{unify-8859-on-decoding-mode} enables a mode that | |
819 | ``unifies'' the Latin alphabets when decoding text. This works by | |
76dd3692 | 820 | converting all non-@acronym{ASCII} Latin-@var{n} characters to either Latin-1 or |
ba2cf799 RS |
821 | Unicode characters. This way it is easier to use various |
822 | Latin-@var{n} alphabets together. In a future Emacs version we hope | |
823 | to move towards full Unicode support and complete unification of | |
824 | character sets. | |
825 | ||
6bf7aab6 DL |
826 | @vindex buffer-file-coding-system |
827 | Once Emacs has chosen a coding system for a buffer, it stores that | |
828 | coding system in @code{buffer-file-coding-system} and uses that coding | |
829 | system, by default, for operations that write from this buffer into a | |
830 | file. This includes the commands @code{save-buffer} and | |
831 | @code{write-region}. If you want to write files from this buffer using | |
832 | a different coding system, you can specify a different coding system for | |
833 | the buffer using @code{set-buffer-file-coding-system} (@pxref{Specify | |
834 | Coding}). | |
835 | ||
4b40407a RS |
836 | You can insert any possible character into any Emacs buffer, but |
837 | most coding systems can only handle some of the possible characters. | |
12de6e26 EZ |
838 | This means that it is possible for you to insert characters that |
839 | cannot be encoded with the coding system that will be used to save the | |
76dd3692 | 840 | buffer. For example, you could start with an @acronym{ASCII} file and insert a |
12de6e26 | 841 | few Latin-1 characters into it, or you could edit a text file in |
a9749dab RS |
842 | Polish encoded in @code{iso-8859-2} and add some Russian words to it. |
843 | When you save the buffer, Emacs cannot use the current value of | |
844 | @code{buffer-file-coding-system}, because the characters you added | |
845 | cannot be encoded by that coding system. | |
2a886892 EZ |
846 | |
847 | When that happens, Emacs tries the most-preferred coding system (set | |
848 | by @kbd{M-x prefer-coding-system} or @kbd{M-x | |
4b40407a RS |
849 | set-language-environment}), and if that coding system can safely |
850 | encode all of the characters in the buffer, Emacs uses it, and stores | |
851 | its value in @code{buffer-file-coding-system}. Otherwise, Emacs | |
852 | displays a list of coding systems suitable for encoding the buffer's | |
cd6eaa1e | 853 | contents, and asks you to choose one of those coding systems. |
4b40407a RS |
854 | |
855 | If you insert the unsuitable characters in a mail message, Emacs | |
856 | behaves a bit differently. It additionally checks whether the | |
857 | most-preferred coding system is recommended for use in MIME messages; | |
9efa2777 | 858 | if not, Emacs tells you that the most-preferred coding system is |
4b40407a RS |
859 | not recommended and prompts you for another coding system. This is so |
860 | you won't inadvertently send a message encoded in a way that your | |
861 | recipient's mail software will have difficulty decoding. (If you do | |
cd6eaa1e | 862 | want to use the most-preferred coding system, you can still type its |
5336b0e0 | 863 | name in response to the question.) |
2a886892 | 864 | |
6bf7aab6 DL |
865 | @vindex sendmail-coding-system |
866 | When you send a message with Mail mode (@pxref{Sending Mail}), Emacs has | |
867 | four different ways to determine the coding system to use for encoding | |
868 | the message text. It tries the buffer's own value of | |
869 | @code{buffer-file-coding-system}, if that is non-@code{nil}. Otherwise, | |
870 | it uses the value of @code{sendmail-coding-system}, if that is | |
871 | non-@code{nil}. The third way is to use the default coding system for | |
872 | new files, which is controlled by your choice of language environment, | |
873 | if that is non-@code{nil}. If all of these three values are @code{nil}, | |
874 | Emacs encodes outgoing mail using the Latin-1 coding system. | |
875 | ||
876 | @vindex rmail-decode-mime-charset | |
877 | When you get new mail in Rmail, each message is translated | |
12de6e26 | 878 | automatically from the coding system it is written in, as if it were a |
6bf7aab6 DL |
879 | separate file. This uses the priority list of coding systems that you |
880 | have specified. If a MIME message specifies a character set, Rmail | |
881 | obeys that specification, unless @code{rmail-decode-mime-charset} is | |
882 | @code{nil}. | |
883 | ||
884 | @vindex rmail-file-coding-system | |
885 | For reading and saving Rmail files themselves, Emacs uses the coding | |
886 | system specified by the variable @code{rmail-file-coding-system}. The | |
887 | default value is @code{nil}, which means that Rmail files are not | |
888 | translated (they are read and written in the Emacs internal character | |
889 | code). | |
890 | ||
891 | @node Specify Coding | |
892 | @section Specifying a Coding System | |
893 | ||
894 | In cases where Emacs does not automatically choose the right coding | |
895 | system, you can use these commands to specify one: | |
896 | ||
897 | @table @kbd | |
898 | @item C-x @key{RET} f @var{coding} @key{RET} | |
201e6b46 RS |
899 | Use coding system @var{coding} for saving or revisiting the visited |
900 | file in the current buffer. | |
6bf7aab6 DL |
901 | |
902 | @item C-x @key{RET} c @var{coding} @key{RET} | |
903 | Specify coding system @var{coding} for the immediately following | |
904 | command. | |
905 | ||
906 | @item C-x @key{RET} k @var{coding} @key{RET} | |
907 | Use coding system @var{coding} for keyboard input. | |
908 | ||
909 | @item C-x @key{RET} t @var{coding} @key{RET} | |
910 | Use coding system @var{coding} for terminal output. | |
911 | ||
912 | @item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET} | |
913 | Use coding systems @var{input-coding} and @var{output-coding} for | |
914 | subprocess input and output in the current buffer. | |
915 | ||
916 | @item C-x @key{RET} x @var{coding} @key{RET} | |
917 | Use coding system @var{coding} for transferring selections to and from | |
918 | other programs through the window system. | |
919 | ||
0771f2b9 RS |
920 | @item C-x @key{RET} F @var{coding} @key{RET} |
921 | Use coding system @var{coding} for encoding and decoding file | |
922 | @emph{names}. This affects the use of non-ASCII characters in file | |
923 | names. It has no effect on reading and writing the @emph{contents} of | |
924 | files. | |
925 | ||
6bf7aab6 DL |
926 | @item C-x @key{RET} X @var{coding} @key{RET} |
927 | Use coding system @var{coding} for transferring @emph{one} | |
928 | selection---the next one---to or from the window system. | |
929 | @end table | |
930 | ||
931 | @kindex C-x RET f | |
932 | @findex set-buffer-file-coding-system | |
201e6b46 RS |
933 | The command @kbd{C-x @key{RET} f} |
934 | (@code{set-buffer-file-coding-system}) sets the file coding system for | |
935 | the current buffer---in other words, it says which coding system to | |
936 | use when saving or reverting the visited file. You specify which | |
937 | coding system using the minibuffer. If you specify a coding system | |
938 | that cannot handle all of the characters in the buffer, Emacs warns | |
939 | you about the troublesome characters when you actually save the | |
940 | buffer. | |
6bf7aab6 DL |
941 | |
942 | @kindex C-x RET c | |
943 | @findex universal-coding-system-argument | |
944 | Another way to specify the coding system for a file is when you visit | |
945 | the file. First use the command @kbd{C-x @key{RET} c} | |
946 | (@code{universal-coding-system-argument}); this command uses the | |
947 | minibuffer to read a coding system name. After you exit the minibuffer, | |
948 | the specified coding system is used for @emph{the immediately following | |
949 | command}. | |
950 | ||
951 | So if the immediately following command is @kbd{C-x C-f}, for example, | |
952 | it reads the file using that coding system (and records the coding | |
201e6b46 | 953 | system for when you later save the file). Or if the immediately following |
6bf7aab6 | 954 | command is @kbd{C-x C-w}, it writes the file using that coding system. |
201e6b46 RS |
955 | When you specify the coding system for saving in this way, instead |
956 | of with @kbd{C-x @key{RET} f}, there is no warning if the buffer | |
957 | contains characters that the coding system cannot handle. | |
6bf7aab6 | 958 | |
201e6b46 RS |
959 | Other file commands affected by a specified coding system include |
960 | @kbd{C-x C-i} and @kbd{C-x C-v}, as well as the other-window variants | |
961 | of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that | |
962 | start subprocesses, including @kbd{M-x shell} (@pxref{Shell}). | |
6bf7aab6 | 963 | |
201e6b46 RS |
964 | If the immediately following command does not use the coding system, |
965 | then @kbd{C-x @key{RET} c} ultimately has no effect. | |
6bf7aab6 DL |
966 | |
967 | An easy way to visit a file with no conversion is with the @kbd{M-x | |
968 | find-file-literally} command. @xref{Visiting}. | |
969 | ||
970 | @vindex default-buffer-file-coding-system | |
971 | The variable @code{default-buffer-file-coding-system} specifies the | |
972 | choice of coding system to use when you create a new file. It applies | |
973 | when you find a new file, and when you create a buffer and then save it | |
974 | in a file. Selecting a language environment typically sets this | |
975 | variable to a good choice of default coding system for that language | |
976 | environment. | |
977 | ||
978 | @kindex C-x RET t | |
979 | @findex set-terminal-coding-system | |
980 | The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system}) | |
981 | specifies the coding system for terminal output. If you specify a | |
982 | character code for terminal output, all characters output to the | |
983 | terminal are translated into that coding system. | |
984 | ||
985 | This feature is useful for certain character-only terminals built to | |
986 | support specific languages or character sets---for example, European | |
987 | terminals that support one of the ISO Latin character sets. You need to | |
988 | specify the terminal coding system when using multibyte text, so that | |
989 | Emacs knows which characters the terminal can actually handle. | |
990 | ||
991 | By default, output to the terminal is not translated at all, unless | |
60245086 DL |
992 | Emacs can deduce the proper coding system from your terminal type or |
993 | your locale specification (@pxref{Language Environments}). | |
6bf7aab6 DL |
994 | |
995 | @kindex C-x RET k | |
996 | @findex set-keyboard-coding-system | |
aa120288 | 997 | @vindex keyboard-coding-system |
6bf7aab6 | 998 | The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system}) |
bdc3b3be RS |
999 | or the variable @code{keyboard-coding-system} specifies the coding |
1000 | system for keyboard input. Character-code translation of keyboard | |
1001 | input is useful for terminals with keys that send non-@acronym{ASCII} | |
1002 | graphic characters---for example, some terminals designed for ISO | |
1003 | Latin-1 or subsets of it. | |
6bf7aab6 | 1004 | |
dfa56e2b RS |
1005 | By default, keyboard input is translated based on your system locale |
1006 | setting. If your terminal does not really support the encoding | |
1007 | implied by your locale (for example, if you find it inserts a | |
76dd3692 | 1008 | non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set |
dfa56e2b RS |
1009 | @code{keyboard-coding-system} to @code{nil} to turn off encoding. |
1010 | You can do this by putting | |
1011 | ||
1012 | @lisp | |
1013 | (set-keyboard-coding-system nil) | |
1014 | @end lisp | |
1015 | ||
1016 | @noindent | |
1017 | in your @file{~/.emacs} file. | |
6bf7aab6 DL |
1018 | |
1019 | There is a similarity between using a coding system translation for | |
1020 | keyboard input, and using an input method: both define sequences of | |
1021 | keyboard input that translate into single characters. However, input | |
1022 | methods are designed to be convenient for interactive use by humans, and | |
76dd3692 | 1023 | the sequences that are translated are typically sequences of @acronym{ASCII} |
6bf7aab6 DL |
1024 | printing characters. Coding systems typically translate sequences of |
1025 | non-graphic characters. | |
1026 | ||
1027 | @kindex C-x RET x | |
1028 | @kindex C-x RET X | |
1029 | @findex set-selection-coding-system | |
1030 | @findex set-next-selection-coding-system | |
1031 | The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system}) | |
1032 | specifies the coding system for sending selected text to the window | |
1033 | system, and for receiving the text of selections made in other | |
1034 | applications. This command applies to all subsequent selections, until | |
1035 | you override it by using the command again. The command @kbd{C-x | |
1036 | @key{RET} X} (@code{set-next-selection-coding-system}) specifies the | |
1037 | coding system for the next selection made in Emacs or read by Emacs. | |
1038 | ||
1039 | @kindex C-x RET p | |
1040 | @findex set-buffer-process-coding-system | |
1041 | The command @kbd{C-x @key{RET} p} (@code{set-buffer-process-coding-system}) | |
1042 | specifies the coding system for input and output to a subprocess. This | |
1043 | command applies to the current buffer; normally, each subprocess has its | |
1044 | own buffer, and thus you can use this command to specify translation to | |
1045 | and from a particular subprocess by giving the command in the | |
1046 | corresponding buffer. | |
1047 | ||
a895a5a5 KH |
1048 | The default for translation of process input and output depends on the |
1049 | current language environment. | |
6bf7aab6 DL |
1050 | |
1051 | @vindex file-name-coding-system | |
76dd3692 | 1052 | @cindex file names with non-@acronym{ASCII} characters |
0771f2b9 RS |
1053 | @findex set-file-name-coding-system |
1054 | @kindex C-x @key{RET} F | |
1055 | The variable @code{file-name-coding-system} specifies a coding | |
1056 | system to use for encoding file names. If you set the variable to a | |
1057 | coding system name (as a Lisp symbol or a string), Emacs encodes file | |
1058 | names using that coding system for all file operations. This makes it | |
1059 | possible to use non-@acronym{ASCII} characters in file names---or, at | |
1060 | least, those non-@acronym{ASCII} characters which the specified coding | |
1061 | system can encode. Use @kbd{C-x @key{RET} F} | |
1062 | (@code{set-file-name-coding-system}) to specify this interactively. | |
6bf7aab6 DL |
1063 | |
1064 | If @code{file-name-coding-system} is @code{nil}, Emacs uses a default | |
1065 | coding system determined by the selected language environment. In the | |
76dd3692 | 1066 | default language environment, any non-@acronym{ASCII} characters in file names are |
6bf7aab6 DL |
1067 | not encoded specially; they appear in the file system using the internal |
1068 | Emacs representation. | |
1069 | ||
1070 | @strong{Warning:} if you change @code{file-name-coding-system} (or the | |
1071 | language environment) in the middle of an Emacs session, problems can | |
1072 | result if you have already visited files whose names were encoded using | |
1073 | the earlier coding system and cannot be encoded (or are encoded | |
1074 | differently) under the new coding system. If you try to save one of | |
1075 | these buffers under the visited file name, saving may use the wrong file | |
1076 | name, or it may get an error. If such a problem happens, use @kbd{C-x | |
1077 | C-w} to specify a new file name for that buffer. | |
1078 | ||
fbc164de | 1079 | @vindex locale-coding-system |
76dd3692 | 1080 | @cindex decoding non-@acronym{ASCII} keyboard input on X |
4b40407a RS |
1081 | The variable @code{locale-coding-system} specifies a coding system |
1082 | to use when encoding and decoding system strings such as system error | |
579cb67d | 1083 | messages and @code{format-time-string} formats and time stamps. That |
76dd3692 | 1084 | coding system is also used for decoding non-@acronym{ASCII} keyboard input on X |
579cb67d EZ |
1085 | Window systems. You should choose a coding system that is compatible |
1086 | with the underlying system's text representation, which is normally | |
1087 | specified by one of the environment variables @env{LC_ALL}, | |
1088 | @env{LC_CTYPE}, and @env{LANG}. (The first one, in the order | |
1089 | specified above, whose value is nonempty is the one that determines | |
1090 | the text representation.) | |
fbc164de | 1091 | |
6bf7aab6 DL |
1092 | @node Fontsets |
1093 | @section Fontsets | |
1094 | @cindex fontsets | |
1095 | ||
12de6e26 | 1096 | A font for X typically defines shapes for a single alphabet or script. |
97878c08 EZ |
1097 | Therefore, displaying the entire range of scripts that Emacs supports |
1098 | requires a collection of many fonts. In Emacs, such a collection is | |
1099 | called a @dfn{fontset}. A fontset is defined by a list of fonts, each | |
1100 | assigned to handle a range of character codes. | |
6bf7aab6 DL |
1101 | |
1102 | Each fontset has a name, like a font. The available X fonts are | |
1103 | defined by the X server; fontsets, however, are defined within Emacs | |
1104 | itself. Once you have defined a fontset, you can use it within Emacs by | |
1105 | specifying its name, anywhere that you could use a single font. Of | |
1106 | course, Emacs fontsets can use only the fonts that the X server | |
1107 | supports; if certain characters appear on the screen as hollow boxes, | |
1108 | this means that the fontset in use for them has no font for those | |
4b40407a | 1109 | characters.@footnote{The Emacs installation instructions have information on |
60245086 | 1110 | additional font support.} |
6bf7aab6 DL |
1111 | |
1112 | Emacs creates two fontsets automatically: the @dfn{standard fontset} | |
1113 | and the @dfn{startup fontset}. The standard fontset is most likely to | |
76dd3692 | 1114 | have fonts for a wide variety of non-@acronym{ASCII} characters; however, this is |
6bf7aab6 | 1115 | not the default for Emacs to use. (By default, Emacs tries to find a |
12de6e26 | 1116 | font that has bold and italic variants.) You can specify use of the |
6bf7aab6 DL |
1117 | standard fontset with the @samp{-fn} option, or with the @samp{Font} X |
1118 | resource (@pxref{Font X}). For example, | |
1119 | ||
1120 | @example | |
1121 | emacs -fn fontset-standard | |
1122 | @end example | |
1123 | ||
1124 | A fontset does not necessarily specify a font for every character | |
1125 | code. If a fontset specifies no font for a certain character, or if it | |
1126 | specifies a font that does not exist on your system, then it cannot | |
1127 | display that character properly. It will display that character as an | |
1128 | empty box instead. | |
1129 | ||
6bf7aab6 DL |
1130 | @node Defining Fontsets |
1131 | @section Defining fontsets | |
1132 | ||
1133 | @vindex standard-fontset-spec | |
1134 | @cindex standard fontset | |
1135 | Emacs creates a standard fontset automatically according to the value | |
1136 | of @code{standard-fontset-spec}. This fontset's name is | |
1137 | ||
1138 | @example | |
1139 | -*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard | |
1140 | @end example | |
1141 | ||
1142 | @noindent | |
1143 | or just @samp{fontset-standard} for short. | |
1144 | ||
1145 | Bold, italic, and bold-italic variants of the standard fontset are | |
1146 | created automatically. Their names have @samp{bold} instead of | |
1147 | @samp{medium}, or @samp{i} instead of @samp{r}, or both. | |
1148 | ||
1149 | @cindex startup fontset | |
76dd3692 | 1150 | If you specify a default @acronym{ASCII} font with the @samp{Font} resource or |
6bf7aab6 DL |
1151 | the @samp{-fn} argument, Emacs generates a fontset from it |
1152 | automatically. This is the @dfn{startup fontset} and its name is | |
1153 | @code{fontset-startup}. It does this by replacing the @var{foundry}, | |
1154 | @var{family}, @var{add_style}, and @var{average_width} fields of the | |
1155 | font name with @samp{*}, replacing @var{charset_registry} field with | |
1156 | @samp{fontset}, and replacing @var{charset_encoding} field with | |
1157 | @samp{startup}, then using the resulting string to specify a fontset. | |
1158 | ||
1159 | For instance, if you start Emacs this way, | |
1160 | ||
1161 | @example | |
1162 | emacs -fn "*courier-medium-r-normal--14-140-*-iso8859-1" | |
1163 | @end example | |
1164 | ||
1165 | @noindent | |
1166 | Emacs generates the following fontset and uses it for the initial X | |
1167 | window frame: | |
1168 | ||
1169 | @example | |
1170 | -*-*-medium-r-normal-*-14-140-*-*-*-*-fontset-startup | |
1171 | @end example | |
1172 | ||
1173 | With the X resource @samp{Emacs.Font}, you can specify a fontset name | |
1174 | just like an actual font name. But be careful not to specify a fontset | |
1175 | name in a wildcard resource like @samp{Emacs*Font}---that wildcard | |
bf74cba1 | 1176 | specification matches various other resources, such as for menus, and |
6bf7aab6 DL |
1177 | menus cannot handle fontsets. |
1178 | ||
1179 | You can specify additional fontsets using X resources named | |
1180 | @samp{Fontset-@var{n}}, where @var{n} is an integer starting from 0. | |
1181 | The resource value should have this form: | |
1182 | ||
1183 | @smallexample | |
1184 | @var{fontpattern}, @r{[}@var{charsetname}:@var{fontname}@r{]@dots{}} | |
1185 | @end smallexample | |
1186 | ||
1187 | @noindent | |
1188 | @var{fontpattern} should have the form of a standard X font name, except | |
1189 | for the last two fields. They should have the form | |
1190 | @samp{fontset-@var{alias}}. | |
1191 | ||
1192 | The fontset has two names, one long and one short. The long name is | |
1193 | @var{fontpattern}. The short name is @samp{fontset-@var{alias}}. You | |
1194 | can refer to the fontset by either name. | |
1195 | ||
1196 | The construct @samp{@var{charset}:@var{font}} specifies which font to | |
1197 | use (in this fontset) for one particular character set. Here, | |
1198 | @var{charset} is the name of a character set, and @var{font} is the | |
1199 | font to use for that character set. You can use this construct any | |
1200 | number of times in defining one fontset. | |
1201 | ||
1202 | For the other character sets, Emacs chooses a font based on | |
1203 | @var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values | |
76dd3692 | 1204 | that describe the character set. For the @acronym{ASCII} character font, |
6bf7aab6 DL |
1205 | @samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}. |
1206 | ||
1207 | In addition, when several consecutive fields are wildcards, Emacs | |
1208 | collapses them into a single wildcard. This is to prevent use of | |
1209 | auto-scaled fonts. Fonts made by scaling larger fonts are not usable | |
1210 | for editing, and scaling a smaller font is not useful because it is | |
12de6e26 EZ |
1211 | better to use the smaller font in its own size, which is what Emacs |
1212 | does. | |
6bf7aab6 DL |
1213 | |
1214 | Thus if @var{fontpattern} is this, | |
1215 | ||
1216 | @example | |
1217 | -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24 | |
1218 | @end example | |
1219 | ||
1220 | @noindent | |
76dd3692 | 1221 | the font specification for @acronym{ASCII} characters would be this: |
6bf7aab6 DL |
1222 | |
1223 | @example | |
1224 | -*-fixed-medium-r-normal-*-24-*-ISO8859-1 | |
1225 | @end example | |
1226 | ||
1227 | @noindent | |
1228 | and the font specification for Chinese GB2312 characters would be this: | |
1229 | ||
1230 | @example | |
1231 | -*-fixed-medium-r-normal-*-24-*-gb2312*-* | |
1232 | @end example | |
1233 | ||
1234 | You may not have any Chinese font matching the above font | |
1235 | specification. Most X distributions include only Chinese fonts that | |
1236 | have @samp{song ti} or @samp{fangsong ti} in @var{family} field. In | |
1237 | such a case, @samp{Fontset-@var{n}} can be specified as below: | |
1238 | ||
1239 | @smallexample | |
1240 | Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\ | |
1241 | chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-* | |
1242 | @end smallexample | |
1243 | ||
1244 | @noindent | |
1245 | Then, the font specifications for all but Chinese GB2312 characters have | |
1246 | @samp{fixed} in the @var{family} field, and the font specification for | |
1247 | Chinese GB2312 characters has a wild card @samp{*} in the @var{family} | |
1248 | field. | |
1249 | ||
1250 | @findex create-fontset-from-fontset-spec | |
1251 | The function that processes the fontset resource value to create the | |
1252 | fontset is called @code{create-fontset-from-fontset-spec}. You can also | |
1253 | call this function explicitly to create a fontset. | |
1254 | ||
1255 | @xref{Font X}, for more information about font naming in X. | |
1256 | ||
60245086 DL |
1257 | @node Undisplayable Characters |
1258 | @section Undisplayable Characters | |
1259 | ||
76dd3692 | 1260 | There may be a some non-@acronym{ASCII} characters that your terminal cannot |
65b4fec5 RS |
1261 | display. Most non-windowing terminals support just a single character |
1262 | set (use the variable @code{default-terminal-coding-system} | |
4b40407a RS |
1263 | (@pxref{Specify Coding}) to tell Emacs which one); characters which |
1264 | can't be encoded in that coding system are displayed as @samp{?} by | |
1265 | default. | |
1266 | ||
1267 | Windowing terminals can display a broader range of characters, but | |
1268 | you may not have fonts installed for all of them; characters that have | |
1269 | no font appear as a hollow box. | |
60245086 | 1270 | |
4b40407a | 1271 | If you use Latin-1 characters but your terminal can't display |
76dd3692 | 1272 | Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences |
4b40407a RS |
1273 | instead, e.g.@: @samp{"o} for o-umlaut. Load the library |
1274 | @file{iso-ascii} to do this. | |
60245086 | 1275 | |
741c4ff9 | 1276 | @vindex latin1-display |
4b40407a RS |
1277 | If your terminal can display Latin-1, you can display characters |
1278 | from other European character sets using a mixture of equivalent | |
bdc3b3be | 1279 | Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable |
76dd3692 | 1280 | @code{latin1-display} to enable this. The mnemonic @acronym{ASCII} |
4b40407a | 1281 | sequences mostly correspond to those of the prefix input methods. |
60245086 | 1282 | |
521ab838 DL |
1283 | @node Single-Byte Character Support |
1284 | @section Single-byte Character Set Support | |
6bf7aab6 DL |
1285 | |
1286 | @cindex European character sets | |
1287 | @cindex accented characters | |
1288 | @cindex ISO Latin character sets | |
1289 | @cindex Unibyte operation | |
6bf7aab6 | 1290 | The ISO 8859 Latin-@var{n} character sets define character codes in |
12de6e26 EZ |
1291 | the range 0240 to 0377 octal (160 to 255 decimal) to handle the |
1292 | accented letters and punctuation needed by various European languages | |
1293 | (and some non-European ones). If you disable multibyte characters, | |
1294 | Emacs can still handle @emph{one} of these character codes at a time. | |
1295 | To specify @emph{which} of these codes to use, invoke @kbd{M-x | |
1296 | set-language-environment} and specify a suitable language environment | |
1297 | such as @samp{Latin-@var{n}}. | |
6bf7aab6 DL |
1298 | |
1299 | For more information about unibyte operation, see @ref{Enabling | |
1300 | Multibyte}. Note particularly that you probably want to ensure that | |
76dd3692 | 1301 | your initialization files are read as unibyte if they contain non-@acronym{ASCII} |
6bf7aab6 DL |
1302 | characters. |
1303 | ||
1304 | @vindex unibyte-display-via-language-environment | |
1305 | Emacs can also display those characters, provided the terminal or font | |
1306 | in use supports them. This works automatically. Alternatively, if you | |
1307 | are using a window system, Emacs can also display single-byte characters | |
1308 | through fontsets, in effect by displaying the equivalent multibyte | |
1309 | characters according to the current language environment. To request | |
1310 | this, set the variable @code{unibyte-display-via-language-environment} | |
1311 | to a non-@code{nil} value. | |
1312 | ||
1313 | @cindex @code{iso-ascii} library | |
1314 | If your terminal does not support display of the Latin-1 character | |
76dd3692 | 1315 | set, Emacs can display these characters as @acronym{ASCII} sequences which at |
6bf7aab6 DL |
1316 | least give you a clear idea of what the characters are. To do this, |
1317 | load the library @code{iso-ascii}. Similar libraries for other | |
1318 | Latin-@var{n} character sets could be implemented, but we don't have | |
1319 | them yet. | |
1320 | ||
1321 | @findex standard-display-8bit | |
1322 | @cindex 8-bit display | |
12de6e26 | 1323 | Normally non-ISO-8859 characters (decimal codes between 128 and 159 |
6bf7aab6 | 1324 | inclusive) are displayed as octal escapes. You can change this for |
2684ed46 | 1325 | non-standard ``extended'' versions of ISO-8859 character sets by using the |
6bf7aab6 DL |
1326 | function @code{standard-display-8bit} in the @code{disp-table} library. |
1327 | ||
76dd3692 | 1328 | There are several ways you can input single-byte non-@acronym{ASCII} |
6bf7aab6 DL |
1329 | characters: |
1330 | ||
1331 | @itemize @bullet | |
521ab838 | 1332 | @cindex 8-bit input |
6bf7aab6 | 1333 | @item |
12de6e26 | 1334 | If your keyboard can generate character codes 128 (decimal) and up, |
76dd3692 | 1335 | representing non-@acronym{ASCII} characters, you can type those character codes |
12de6e26 | 1336 | directly. |
4b40407a RS |
1337 | |
1338 | On a windowing terminal, you should not need to do anything special to | |
1339 | use these keys; they should simply work. On a text-only terminal, you | |
1340 | should use the command @code{M-x set-keyboard-coding-system} or the | |
bdc3b3be | 1341 | variable @code{keyboard-coding-system} to specify which coding |
4b40407a RS |
1342 | system your keyboard uses (@pxref{Specify Coding}). Enabling this |
1343 | feature will probably require you to use @kbd{ESC} to type Meta | |
bdc3b3be | 1344 | characters; however, on a console terminal or in @code{xterm}, you can |
4b40407a RS |
1345 | arrange for Meta to be converted to @kbd{ESC} and still be able type |
1346 | 8-bit characters present directly on the keyboard or using | |
1347 | @kbd{Compose} or @kbd{AltGr} keys. @xref{User Input}. | |
521ab838 | 1348 | |
6bf7aab6 DL |
1349 | @item |
1350 | You can use an input method for the selected language environment. | |
1351 | @xref{Input Methods}. When you use an input method in a unibyte buffer, | |
76dd3692 | 1352 | the non-@acronym{ASCII} character you specify with it is converted to unibyte. |
6bf7aab6 DL |
1353 | |
1354 | @kindex C-x 8 | |
1355 | @cindex @code{iso-transl} library | |
98c271eb DL |
1356 | @cindex compose character |
1357 | @cindex dead character | |
6bf7aab6 DL |
1358 | @item |
1359 | For Latin-1 only, you can use the | |
1360 | key @kbd{C-x 8} as a ``compose character'' prefix for entry of | |
76dd3692 | 1361 | non-@acronym{ASCII} Latin-1 printing characters. @kbd{C-x 8} is good for |
6bf7aab6 DL |
1362 | insertion (in the minibuffer as well as other buffers), for searching, |
1363 | and in any other context where a key sequence is allowed. | |
1364 | ||
1365 | @kbd{C-x 8} works by loading the @code{iso-transl} library. Once that | |
1366 | library is loaded, the @key{ALT} modifier key, if you have one, serves | |
1367 | the same purpose as @kbd{C-x 8}; use @key{ALT} together with an accent | |
1368 | character to modify the following letter. In addition, if you have keys | |
4b40407a | 1369 | for the Latin-1 ``dead accent characters,'' they too are defined to |
6bf7aab6 | 1370 | compose with the following character, once @code{iso-transl} is loaded. |
133f8c71 DL |
1371 | Use @kbd{C-x 8 C-h} to list the available translations as mnemonic |
1372 | command names. | |
1373 | ||
133f8c71 | 1374 | @item |
98c271eb DL |
1375 | @cindex @code{iso-acc} library |
1376 | @cindex ISO Accents mode | |
1377 | @findex iso-accents-mode | |
13142d70 | 1378 | @cindex Latin-1, Latin-2 and Latin-3 input mode |
5336b0e0 RS |
1379 | For Latin-1, Latin-2 and Latin-3, @kbd{M-x iso-accents-mode} enables |
1380 | a minor mode that works much like the @code{latin-1-prefix} input | |
cd6eaa1e | 1381 | method, but does not depend on having the input methods installed. This |
4b40407a RS |
1382 | mode is buffer-local. It can be customized for various languages with |
1383 | @kbd{M-x iso-accents-customize}. | |
6bf7aab6 | 1384 | @end itemize |
52254d1a RS |
1385 | |
1386 | @node Charsets | |
1387 | @section Charsets | |
1388 | @cindex charsets | |
1389 | ||
1390 | Emacs groups all supported characters into disjoint @dfn{charsets}. | |
1391 | Each character code belongs to one and only one charset. For | |
1392 | historical reasons, Emacs typically divides an 8-bit character code | |
76dd3692 | 1393 | for an extended version of @acronym{ASCII} into two charsets: @acronym{ASCII}, which |
52254d1a RS |
1394 | covers the codes 0 through 127, plus another charset which covers the |
1395 | ``right-hand part'' (the codes 128 and up). For instance, the | |
1396 | characters of Latin-1 include the Emacs charset @code{ascii} plus the | |
1397 | Emacs charset @code{latin-iso8859-1}. | |
1398 | ||
1399 | Emacs characters belonging to different charsets may look the same, | |
1400 | but they are still different characters. For example, the letter | |
1401 | @samp{o} with acute accent in charset @code{latin-iso8859-1}, used for | |
1402 | Latin-1, is different from the letter @samp{o} with acute accent in | |
1403 | charset @code{latin-iso8859-2}, used for Latin-2. | |
1404 | ||
1405 | @findex list-charset-chars | |
1406 | @cindex characters in a certain charset | |
1407 | @findex describe-character-set | |
1408 | There are two commands for obtaining information about Emacs | |
1409 | charsets. The command @kbd{M-x list-charset-chars} prompts for a name | |
1410 | of a character set, and displays all the characters in that character | |
1411 | set. The command @kbd{M-x describe-character-set} prompts for a | |
1412 | charset name and displays information about that charset, including | |
1413 | its internal representation within Emacs. | |
1414 | ||
1415 | To find out which charset a character in the buffer belongs to, | |
1416 | put point before it and type @kbd{C-u C-x =}. | |
ab5796a9 MB |
1417 | |
1418 | @ignore | |
1419 | arch-tag: 310ba60d-31ef-4ce7-91f1-f282dd57b6b3 | |
1420 | @end ignore |