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1 <?xml version='1.0' encoding="UTF-8"?>
2 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/utf-8.xml,v 1.5 2005/02/24 14:57:18 cam Exp $ -->
3 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
5 <guide link="/doc/en/utf-8.xml">
6 <title>Using UTF-8 with Gentoo</title>
8 <author title="Author">
9 <mail link="slarti@gentoo.org">Thomas Martin</mail>
10 </author>
11 <author title="Contributor">
12 <mail link="devil@gentoo.org.ua">Alexander Simonov</mail>
13 </author>
15 <abstract>
16 This guide shows you how to set up and use the UTF-8 Unicode character set with
17 your Gentoo Linux system, after explaining the benefits of Unicode and more
18 specifically UTF-8.
19 </abstract>
21 <license />
23 <version>1.5</version>
24 <date>2005-04-23</date>
26 <chapter>
27 <title>Character Encodings</title>
28 <section>
29 <title>What is a Character Encoding?</title>
30 <body>
32 <p>
33 Computers do not understand text themselves. Instead, every character is
34 represented by a number. Traditionally, each set of numbers used to represent
35 alphabets and characters (known as a coding system, encoding or character set)
36 was limited in size due to limitations in computer hardware.
37 </p>
39 </body>
40 </section>
41 <section>
42 <title>The History of Character Encodings</title>
43 <body>
45 <p>
46 The most common (or at least the most widely accepted) character set is
47 <b>ASCII</b> (American Standard Code for Information Interchange). It is widely
48 held that ASCII is the most successful software standard ever. Modern ASCII
49 was standardised in 1986 (ANSI X3.4, RFC 20, ISO/IEC 646:1991, ECMA-6) by the
50 American National Standards Institute.
51 </p>
53 <p>
54 ASCII is strictly seven-bit, meaning that it uses bit patterns representable
55 with seven binary digits, which provides a range of 0 to 127 in decimal. These
56 include 32 non-visible control characters, most between 0 and 31, with the
57 final control character, DEL or delete at 127. Characters 32 to 126 are
58 visible characters: a space, punctuation marks, Latin letters and numbers.
59 </p>
61 <p>
62 The eighth bit in ASCII was originally used as a parity bit for error checking.
63 If this is not desired, it is left as 0. This means that, with ASCII, each
64 character is represented by a single byte.
65 </p>
67 <p>
68 Although ASCII was enough for communication in modern English, in other
69 European languages that include accented characters, things were not so easy.
70 The ISO 8859 standards were developed to meet these needs. They were backwards
71 compatible with ASCII, but instead of leaving the eighth bit blank, they used
72 it to allow another 127 characters in each encoding. ISO 8859's limitations
73 soon came to light, and there are currently 15 variants of the ISO 8859
74 standard (8859-1 through to 8859-15). Outside of the ASCII-compatible byte
75 range of these character sets, there is often conflict between the letters
76 represented by each byte. To complicate interoperability between character
77 encodings further, Windows-1252 is used in some versions of Microsoft Windows
78 instead for Western European languages. This is a superset of ISO 8859-1,
79 however it is different in several ways. These sets do all retain ASCII
80 compatibility, however.
81 </p>
83 <p>
84 The necessary development of completely different single-byte encodings for
85 non-Latin alphabets, such as EUC (Extended Unix Coding) which is used for
86 Japanese and Korean (and to a lesser extent Chinese) created more confusion,
87 while other operating systems still used different character sets for the same
88 languages, for example, Shift-JIS and ISO-2022-JP. Users wishing to view
89 cyrillic glyphs had to choose between KOI8-R for Russian and Bulgarian or
90 KOI8-U for Ukrainian, as well as all the other cyrillic encodings such as the
91 unsuccessful ISO 8859-5, and the common Windows-1251 set. All of these
92 character sets broke most compatibility with ASCII (although KOI8 encodings
93 place cyrillic characters in Latin order, so in case the eighth bit is
94 stripped, text is still decipherable on an ASCII terminal through case-reversed
95 transliteration.)
96 </p>
98 <p>
99 This has led to confusion, and also to an almost total inability for
100 multilingual communication, especially across different alphabets. Enter
101 Unicode.
102 </p>
104 </body>
105 </section>
106 <section>
107 <title>What is Unicode?</title>
108 <body>
110 <p>
111 Unicode throws away the traditional single-byte limit of character sets, and
112 even with two bytes per-character this allows a maximum 65,536 characters.
113 Although this number is extremely high when compared to seven-bit and eight-bit
114 encodings, it is still not enough for a character set designed to be used for
115 symbols and scripts used only by scholars, and symbols that are only used in
116 mathematics and other specialised fields.
117 </p>
119 <p>
120 Unicode has been mapped in many different ways, but the two most common are
121 <b>UTF</b> (Unicode Transformation Format) and <b>UCS</b> (Universal Character
122 Set). A number after UTF indicates the number of bits in one unit, while the
123 number after UCS indicates the number of bytes. UTF-8 has become the most
124 widespread means for the interchange of Unicode text as a result of its
125 eight-bit clean nature, and it is the subject of this document.
126 </p>
128 </body>
129 </section>
130 <section>
131 <title>UTF-8</title>
132 <body>
134 <p>
135 UTF-8 is a variable-length character encoding, which in this instance means
136 that it uses 1 to 4 bytes per symbol. So, the first UTF-8 byte is used for
137 encoding ASCII, giving the character set full backwards compatibility with
138 ASCII. UTF-8 means that ASCII and Latin characters are interchangeable with
139 little increase in the size of the data, because only the first bit is used.
140 Users of Eastern alphabets such as Japanese, who have been assigned a higher
141 byte range are unhappy, as this results in as much as a 50% redundancy in their
142 data.
143 </p>
145 </body>
146 </section>
147 <section>
148 <title>What UTF-8 Can Do for You</title>
149 <body>
151 <p>
152 UTF-8 allows you to work in a standards-compliant and internationally accepted
153 multilingual environment, with a comparitively low data redundancy. UTF-8 is
154 the preferred way for transmitting non-ASCII characters over the Internet,
155 through Email, IRC or almost any other medium. Despite this, many people regard
156 UTF-8 in online communication as abusive. It is always best to be aware of the
157 attitude towards UTF-8 in a specific channel, mailing list or Usenet group
158 before using <e>non-ASCII</e> UTF-8.
159 </p>
161 </body>
162 </section>
163 </chapter>
165 <chapter>
166 <title>Setting up UTF-8 with Gentoo Linux</title>
167 <section>
168 <title>Finding or Creating UTF-8 Locales</title>
169 <body>
171 <p>
172 Now that you understand the principles behind Unicode, you're ready to start
173 using UTF-8 with your system.
174 </p>
176 <p>
177 The preliminary requirement for UTF-8 is to have a version of glibc installed
178 that has national language support. The recommend means to do this is the
179 <path>/etc/locales.build</path> file in combination with the <c>userlocales</c>
180 USE flag. It is beyond the scope of this document to explain the usage of this
181 file though, luckily, the usage of this file is well documented in the comments
182 within it. It is also explained in the <uri
183 link="/doc/en/guide-localization.xml#doc_chap3_sect3"> Gentoo Localisation
184 Guide</uri>.
185 </p>
187 <p>
188 Next, we'll need to decide whether a UTF-8 locale is already available for our
189 language, or whether we need to create one.
190 </p>
192 <pre caption="Checking for an existing UTF-8 locale">
193 <comment>(Replace "en_GB" with your desired locale setting)</comment>
194 # <i>locale -a | grep 'en_GB'</i>
195 en_GB
196 en_GB.utf8
197 </pre>
199 <p>
200 From the output of this command line, we need to take the result with a suffix
201 similar to <c>.utf8</c>. If there is no result with a suffix similar to
202 <c>.utf8</c>, we need to create a UTF-8 compatible locale.
203 </p>
205 <note>
206 Only execute the following code listing if you do not have a UTF-8 locale
207 available for your language.
208 </note>
210 <pre caption="Creating a UTF-8 locale">
211 <comment>(Replace "en_GB" with your desired locale setting)</comment>
212 # <i>localedef -i en_GB -f UTF-8 en_GB.utf8</i>
213 </pre>
215 </body>
216 </section>
217 <section>
218 <title>Setting the Locale</title>
219 <body>
221 <p>
222 There are two environment variables that need to be set in order to use
223 our new UTF-8 locales: <c>LANG</c> and <c>LC_ALL</c>. There are also
224 many different ways to set them; some people prefer to only have a UTF-8
225 environment for a specific user, in which case they set them in their
226 <path>~/.profile</path> or <path>~/.bashrc</path>. Others prefer to set the
227 locale globally. One specific circumstance where the author particularly
228 recommends doing this is when <path>/etc/init.d/xdm</path> is in use, because
229 this init script starts the display manager and desktop before any of the
230 aforementioned shell startup files are sourced, and so before any of the
231 variables are in the environment.
232 </p>
234 <p>
235 Setting the locale globally should be done using
236 <path>/etc/env.d/02local</path>. The file should look something like the
237 following:
238 </p>
240 <pre caption="Demonstration /etc/env.d/02locale">
241 <comment>(As always, change "en_GB.UTF-8" to your locale)</comment>
242 LC_ALL="en_GB.UTF-8"
243 LOCALE="en_GB.UTF-8"
244 </pre>
246 <p>
247 Next, the environment must be updated with the change.
248 </p>
250 <pre caption="Updating the environment">
251 # <i>env-update</i>
252 >>> Regenerating /etc/ld.so.cache...
253 * Caching service dependencies ...
254 # <i>source /etc/profile</i>
255 </pre>
257 <p>
258 Now, run <c>locale</c> with no arguments to see if we have the correct
259 variables in our environment:
260 </p>
262 <pre caption="Checking if our new locale is in the environment">
263 # <i>locale</i>
264 LANG=en_GB.UTF-8
265 LC_CTYPE="en_GB.UTF-8"
266 LC_NUMERIC="en_GB.UTF-8"
267 LC_TIME="en_GB.UTF-8"
268 LC_COLLATE="en_GB.UTF-8"
271 LC_PAPER="en_GB.UTF-8"
272 LC_NAME="en_GB.UTF-8"
273 LC_ADDRESS="en_GB.UTF-8"
277 LC_ALL=en_GB.UTF-8
278 </pre>
280 <p>
281 That is all. You are now using UTF-8 locales, and the next hurdle is the
282 configuration of the applications you use from day to day.
283 </p>
285 </body>
286 </section>
287 </chapter>
289 <chapter>
290 <title>Application Support</title>
291 <section>
292 <body>
294 <p>
295 When Unicode first started gaining momentum in the software world, multibyte
296 character sets were not well suited to languages like C, in which many of the
297 day-to-day programs people use are written. Even today, some programs are not
298 able to handle UTF-8 properly. Fortunately, most are!
299 </p>
301 </body>
302 </section>
303 <section>
304 <title>Filenames, NTFS, and FAT</title>
305 <body>
307 <p>
308 There are several NLS options in the Linux kernel configuration menu, but it is
309 important to not become confused! For the most part, the only thing you need to
310 do is to build UTF-8 NLS support into your kernel, and change the default NLS
311 option to utf8.
312 </p>
314 <pre caption="Kernel configuration steps for UTF-8 NLS">
315 File Systems --&gt;
316 Native Language Support --&gt;
317 (utf8) Default NLS Option
318 &lt;*&gt; NLS UTF8
319 <comment>(Also &lt;*&gt; other character sets that are in use in
320 your FAT filesystems or Joilet CD-ROMs.)</comment>
321 </pre>
323 <p>
324 If you plan on mounting NTFS partitions, you may need to specify an <c>nls=</c>
325 option with mount. For more information, see <c>man mount</c>.
326 </p>
328 <p>
329 For changing the encoding of filenames, <c>app-text/convmv</c> can be used.
330 </p>
332 <pre caption="Example usage of convmv">
333 # <i>emerge --ask app-text/convmv</i>
334 # <i>convmv -f current-encoding -t utf-8 filename</i>
335 </pre>
337 <p>
338 For changing the <e>contents</e> of files, use the <c>iconv</c> utility,
339 bundled with <c>glibc</c>:
340 </p>
342 <pre caption="Example usage of iconv">
343 <comment>(substitute iso-8859-1 with the charset you are converting from)</comment>
344 <comment>(Check the output is sane)</comment>
345 # <i>iconv -f iso-8859-1 -t utf-8 filename</i>
346 <comment>(Convert a file, you must create another file)</comment>
347 # <i>iconv -f iso-8859-1 -t utf-8 filename > newfile</i>
348 </pre>
350 <p>
351 <c>app-text/recode</c> can also be used for this purpose.
352 </p>
354 </body>
355 </section>
356 <section>
357 <title>The System Console</title>
358 <body>
360 <impo>
361 You need >=sys-apps/baselayout-1.11.9 for Unicode on the console.
362 </impo>
364 <p>
365 To enable UTF-8 on the console, you should edit <path>/etc/rc.conf</path> and
366 set <c>UNICODE="yes"</c>, and also read the comments in that file -- it is
367 important to have a font that has a good range of characters if you plan on
368 making the most of Unicode.
369 </p>
371 <p>
372 The <c>KEYMAP</c> variable, set in <path>/etc/conf.d/keymaps</path>, should
373 have a Unicode keymap specified. To do this, simply prepend the keymap already
374 specified there with -u.
375 </p>
377 <pre caption="Example /etc/conf.d/keymaps snippet">
378 <comment>(Change "uk" to your local layout)</comment>
379 KEYMAP="uk"
380 </pre>
382 </body>
383 </section>
384 <section>
385 <title>Ncurses and Slang</title>
386 <body>
388 <note>
389 Ignore any mention of Slang in this section if you do not have it installed or
390 do not use it.
391 </note>
393 <p>
394 It is wise to add <c>unicode</c> to your global USE flags in
395 <path>/etc/make.conf</path>, and then to remerge <c>sys-libs/ncurses</c> and
396 also <c>sys-libs/slang</c> if appropriate:
397 </p>
399 <pre caption="Emerging ncurses and slang">
400 <comment>(We avoid putting these libraries in our world file with --oneshot)</comment>
401 # <i>emerge --oneshot --verbose --ask sys-libs/ncurses sys-libs/slang</i>
402 </pre>
404 <p>
405 We also need to rebuild packages that link to these, now the USE changes have
406 been applied.
407 </p>
409 <pre caption="Rebuilding of programs that link to ncurses or slang">
410 # <i>revdep-rebuild --soname libncurses.so.5</i>
411 # <i>revdep-rebuild --soname libslang.so.1</i>
412 </pre>
414 </body>
415 </section>
416 <section>
417 <title>KDE, GNOME and Xfce</title>
418 <body>
420 <p>
421 All of the major desktop environments have full Unicode support, and will
422 require no further setup than what has already been covered in this guide. This
423 is because the underlying graphical toolkits (Qt or GTK+2) are UTF-8 aware.
424 Subsequently, all applications running on top of these toolkits should be
425 UTF-8-aware out of the box.
426 </p>
428 <p>
429 The exceptions to this rule come in Xlib and GTK+1. GTK+1 requires a
430 iso-10646-1 FontSpec in the ~/.gtkrc, for example
431 <c>-misc-fixed-*-*-*-*-*-*-*-*-*-*-iso10646-1</c>. Also, applications using
432 Xlib or Xaw will need to be given a similar FontSpec, otherwise they will not
433 work.
434 </p>
436 <note>
437 If you have a version of the gnome1 control center around, use that instead.
438 Pick any iso10646-1 font from there.
439 </note>
441 <pre caption="Example ~/.gtkrc (for GTK+1) that defines a Unicode compatible font">
442 style "user-font"
443 {
444 fontset="-misc-fixed-*-*-*-*-*-*-*-*-*-*-iso10646-1"
445 }
446 widget_class "*" style "user-font"
447 </pre>
449 <p>
450 If an application has support for both a Qt and GTK+2 GUI, the GTK+2 GUI will
451 generally give better results with Unicode.
452 </p>
454 </body>
455 </section>
456 <section>
457 <title>X11 and Fonts</title>
458 <body>
460 <p>
461 TrueType fonts have support for Unicode, and most of the fonts that ship with
462 Xorg have impressive character support, although, obviously, not every single
463 glyph available in Unicode has been created for that font. To build fonts
464 (including the Bitstream Vera set) with support for East Asian letters with X,
465 make sure you have the <c>cjk</c> USE flag set. Many other applications utilise
466 this flag, so it may be worthwhile to add it as a permanent USE flag.
467 </p>
469 <p>
470 Also, several font packages in Portage are Unicode aware.
471 </p>
473 <pre caption="Optional: Install some more Unicode-aware fonts">
474 # <i>emerge terminus-font intlfonts freefonts cronyx-fonts corefonts</i>
475 </pre>
477 </body>
478 </section>
479 <section>
480 <title>Window Managers and Terminal Emulators</title>
481 <body>
483 <p>
484 Window managers, even those not built on GTK or Qt, generally have very
485 good Unicode support, as they often use the Xft library for handling
486 fonts. If your window manager does not use Xft for fonts, you can still
487 use the FontSpec mentioned in the previous section as a Unicode font.
488 </p>
490 <p>
491 Terminal emulators that use Xft and support Unicode are harder to come by.
492 Aside from Konsole and gnome-terminal, the best options in Portage are
493 <c>x11-terms/rxvt-unicode</c>, <c>xfce-extra/terminal</c>,
494 <c>gnustep-apps/terminal</c>, <c>x11-terms/mlterm</c>, <c>x11-terms/mrxvt</c> or
495 plain <c>x11-terms/xterm</c> when built with the <c>unicode</c> USE flag and
496 invoked as <c>uxterm</c>. <c>app-misc/screen</c> supports UTF-8 too, when
497 invoked as <c>screen -U</c> or the following is put into the
498 <path>~/.screenrc</path>:
499 </p>
501 <pre caption="~/.screenrc for UTF-8">
502 defutf8 on
503 </pre>
505 </body>
506 </section>
507 <section>
508 <title>Vim, Emacs, Xemacs and Nano</title>
509 <body>
511 <p>
512 Vim, Emacs and Xemacs provide full UTF-8 support, and also have builtin
513 detection of UTF-8 files. For further information in Vim, use <c>:help
514 mbyte.txt</c>.
515 </p>
517 <p>
518 Nano currently does not provide support for UTF-8, although it has been planned
519 for a long time. With luck, this will change in future. At the time of writing,
520 UTF-8 support is in Nano's CVS, and should be included in the next release.
521 </p>
523 </body>
524 </section>
525 <section>
526 <title>Shells</title>
527 <body>
529 <p>
530 Currently, <c>bash</c> provides full Unicode support through the GNU readline
531 library. Z Shell users are in a somewhat worse position -- no parts of the
532 shell have Unicode support, although there is a concerted effort to add
533 multibyte character set support underway at the moment.
534 </p>
536 <p>
537 The C shell, <c>tcsh</c> and <c>ksh</c> do not provide UTF-8 support at all.
538 </p>
540 <note>
541 Although not strictly related to shells, many of the GNU text-processing
542 programs in your system (<c>tr</c>, <c>grep</c>, etc.) are much slower
543 when processing Unicode. Nonetheless, the difference is not at all
544 noticeable in nearly every case, but if you are ever hit by these bugs
545 then at least you will know what is causing them. Perl also tends to be
546 slower when operating on multibyte characters. The author knows of one
547 other gotcha: <c>tr</c> will not convert three-byte UTF-8 characters to
548 two-byte UTF-8 characters.
549 </note>
551 </body>
552 </section>
553 <section>
554 <title>Irssi</title>
555 <body>
557 <p>
558 Since 0.8.10, Irssi has complete UTF-8 support, although it does require a user
559 to set an option.
560 </p>
562 <pre caption="Enabling UTF-8 in Irssi">
563 /set term_charset UTF-8
564 </pre>
566 <p>
567 For channels where non-ASCII characters are often exchanged in non-UTF-8
568 charsets, the <c>/recode</c> command may be used to convert the characters.
569 Type <c>/help recode</c> for more information.
570 </p>
572 </body>
573 </section>
574 <section>
575 <title>Mutt</title>
576 <body>
578 <p>
579 The Mutt mail user agent has very good Unicode support. To use UTF-8 with Mutt,
580 put the following in your <path>~/.muttrc</path>:
581 </p>
583 <pre caption="~/.muttrc for UTF-8">
584 set send_charset="utf8" <comment>(outgoing character set)</comment>
585 set charset="utf8" <comment>(display character set)</comment>
586 </pre>
588 <note>
589 You may still see '?' in mail you read with Mutt. This is a result of people
590 using Latin (ISO 8859) or another charset for email transmission. It is best to
591 tell them to use UTF-8 for mail, and point them to the IETF RFC 2277 (see
592 References at the end of this document). Also note that in some lists,
593 subscribers may not like UTF-8. Be sure that the group or person you are
594 communicating with does not mind UTF-8.
595 </note>
597 <p>
598 Further information is available from the <uri
599 link="http://wiki.mutt.org/index.cgi?MuttFaq/Charset"> Mutt WikiWiki</uri>.
600 </p>
602 </body>
603 </section>
604 <section>
605 <title>Testing it all out</title>
606 <body>
608 <p>
609 There are numerous UTF-8 test websites around. <c>net-www/w3m</c>,
610 <c>net-www/links</c>, <c>net-www/elinks</c>, <c>net-www/lynx</c> and all
611 Mozilla based browsers (including Firefox) support UTF-8. Konqueror and Opera
612 have full UTF-8 support too.
613 </p>
615 <p>
616 When using one of the text-only web browsers, make absolutely sure you are
617 using a Unicode-aware terminal.
618 </p>
620 <p>
621 If you see certain characters displayed as boxes with letters or numbers
622 inside, this means that your font does not have a character for the symbol or
623 glyph that the UTF-8 wants. Instead, it displays a box with the hex code of the
624 UTF-8 symbol.
625 </p>
627 <ul>
628 <li>
629 <uri link="http://www.w3.org/2001/06/utf-8-test/UTF-8-demo.html">A W3C
630 UTF-8 Test Page</uri>
631 </li>
632 <li>
633 <uri link="http://titus.uni-frankfurt.de/indexe.htm?/unicode/unitest.htm">
634 A UTF-8 test page provided by the University of Frankfurt</uri>
635 </li>
636 </ul>
638 </body>
639 </section>
640 <section>
641 <title>Input Methods</title>
642 <body>
644 <p>
645 <e>Dead keys</e> may be used to input characters in X that are not included on
646 your keyboard. These work by pressing your right Alt key (or in some countries,
647 AltGr) and an optional key from the non-alphabetical section of the keyboard to
648 the left of the return key at once, releasing them, and then pressing a letter.
649 The dead key should modify it. Input can be further modified by using the Shift
650 key at the same time as pressing the AltGr and modifier.
651 </p>
653 <p>
654 To enable dead keys in X, you need a layout that supports it. Most European
655 layouts already have dead keys with the default variant. However, this is not
656 true of North American layouts. Although there is a degree of inconsistency
657 between layouts, the easiest solution seems to be to use a layout in the form
658 "en_US" rather than "us", for example. The layout is set in
659 <path>/etc/X11/xorg.conf</path> like so:
660 </p>
662 <pre caption="/etc/X11/xorg.conf snippet">
663 Section "InputDevice"
664 Identifier "Keyboard0"
665 Driver "kbd"
666 Option "XkbLayout" "en_US" <comment># Rather than just "us"</comment>
667 <comment>(Other Xkb options here)</comment>
668 EndSection
669 </pre>
671 <note>
672 The preceding change only needs to be applied if you are using a North American
673 layout, or another layout where dead keys do not seem to be working. European
674 users should have working dead keys as is.
675 </note>
677 <p>
678 This change will come into effect when the X server is restarted. To apply the
679 change now, use the <c>setxkbmap</c> tool, for example, <c>setxkbmap en_US</c>.
680 </p>
682 <p>
683 It is probably easiest to describe dead keys with examples. Although the
684 results are layout dependent, the concepts should remain the same regardless of
685 locale. The examples contain UTF-8, so to view them you need to either tell
686 your browser to view the page as UTF-8, or have a UTF-8 locale already
687 configured.
688 </p>
690 <p>
691 When I press AltGr and [ at once, release them, and then press a, 'ä' is
692 produced. When I press AltGr and [ at once, and then press e, 'ë' is
693 produced. When I press AltGr and ; at once, release them, and press a,
694 'á' is produced, and when I press AltGr and ; at once, release them, and
695 then press e, 'é' is produced.
696 </p>
698 <p>
699 By pressing AltGr, Shift and [ at once, releasing them, and then pressing a, a
700 Scandinavian 'å' is produced. Similarly, when I press AltGr, Shift and [ at
701 once, release <e>only</e> the [, and then press it again, '˚' is produced.
702 Although it looks like one, this (U+02DA) is not the same as a degree symbol
703 (U+00B0). This works for other accents produced by dead keys — AltGr and [,
704 releasing only the [, then pressing it again makes '¨'.
705 </p>
707 <p>
708 AltGr can be used with alphabetical keys alone. For example, AltGr and m, a
709 Greek lower-case letter mu is produced: 'µ'. AltGr and s produce a
710 Schauffer's s: 'ß'. As many European users would expect (because it is
711 marked on their keyboard), AltGr and 4 produces a Euro sign, '€'.
712 </p>
714 </body>
715 </section>
716 <section>
717 <title>Resources</title>
718 <body>
720 <ul>
721 <li>
722 <uri link="http://www.wikipedia.com/wiki/Unicode">The Wikipedia entry for
723 Unicode</uri>
724 </li>
725 <li>
726 <uri link="http://www.wikipedia.com/wiki/UTF-8">The Wikipedia entry for
727 UTF-8</uri>
728 </li>
729 <li><uri link="http://www.unicode.org">Unicode.org</uri></li>
730 <li><uri link="http://www.utf-8.com">UTF-8.com</uri></li>
731 <li><uri link="http://www.ietf.org/rfc/rfc3629.txt">RFC 3629</uri></li>
732 <li><uri link="http://www.ietf.org/rfc/rfc2277.txt">RFC 2277</uri></li>
733 </ul>
735 </body>
736 </section>
737 </chapter>
738 </guide>

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