xref: /linux/Documentation/admin-guide/unicode.rst (revision 96ac6d435100450f0565708d9b885ea2a7400e0a)
1Unicode support
2===============
3
4		 Last update: 2005-01-17, version 1.4
5
6This file is maintained by H. Peter Anvin <unicode@lanana.org> as part
7of the Linux Assigned Names And Numbers Authority (LANANA) project.
8The current version can be found at:
9
10	    http://www.lanana.org/docs/unicode/admin-guide/unicode.rst
11
12Introduction
13------------
14
15The Linux kernel code has been rewritten to use Unicode to map
16characters to fonts.  By downloading a single Unicode-to-font table,
17both the eight-bit character sets and UTF-8 mode are changed to use
18the font as indicated.
19
20This changes the semantics of the eight-bit character tables subtly.
21The four character tables are now:
22
23=============== =============================== ================
24Map symbol	Map name			Escape code (G0)
25=============== =============================== ================
26LAT1_MAP	Latin-1 (ISO 8859-1)		ESC ( B
27GRAF_MAP	DEC VT100 pseudographics	ESC ( 0
28IBMPC_MAP	IBM code page 437		ESC ( U
29USER_MAP	User defined			ESC ( K
30=============== =============================== ================
31
32In particular, ESC ( U is no longer "straight to font", since the font
33might be completely different than the IBM character set.  This
34permits for example the use of block graphics even with a Latin-1 font
35loaded.
36
37Note that although these codes are similar to ISO 2022, neither the
38codes nor their uses match ISO 2022; Linux has two 8-bit codes (G0 and
39G1), whereas ISO 2022 has four 7-bit codes (G0-G3).
40
41In accordance with the Unicode standard/ISO 10646 the range U+F000 to
42U+F8FF has been reserved for OS-wide allocation (the Unicode Standard
43refers to this as a "Corporate Zone", since this is inaccurate for
44Linux we call it the "Linux Zone").  U+F000 was picked as the starting
45point since it lets the direct-mapping area start on a large power of
46two (in case 1024- or 2048-character fonts ever become necessary).
47This leaves U+E000 to U+EFFF as End User Zone.
48
49[v1.2]: The Unicodes range from U+F000 and up to U+F7FF have been
50hard-coded to map directly to the loaded font, bypassing the
51translation table.  The user-defined map now defaults to U+F000 to
52U+F0FF, emulating the previous behaviour.  In practice, this range
53might be shorter; for example, vgacon can only handle 256-character
54(U+F000..U+F0FF) or 512-character (U+F000..U+F1FF) fonts.
55
56
57Actual characters assigned in the Linux Zone
58--------------------------------------------
59
60In addition, the following characters not present in Unicode 1.1.4
61have been defined; these are used by the DEC VT graphics map.  [v1.2]
62THIS USE IS OBSOLETE AND SHOULD NO LONGER BE USED; PLEASE SEE BELOW.
63
64====== ======================================
65U+F800 DEC VT GRAPHICS HORIZONTAL LINE SCAN 1
66U+F801 DEC VT GRAPHICS HORIZONTAL LINE SCAN 3
67U+F803 DEC VT GRAPHICS HORIZONTAL LINE SCAN 7
68U+F804 DEC VT GRAPHICS HORIZONTAL LINE SCAN 9
69====== ======================================
70
71The DEC VT220 uses a 6x10 character matrix, and these characters form
72a smooth progression in the DEC VT graphics character set.  I have
73omitted the scan 5 line, since it is also used as a block-graphics
74character, and hence has been coded as U+2500 FORMS LIGHT HORIZONTAL.
75
76[v1.3]: These characters have been officially added to Unicode 3.2.0;
77they are added at U+23BA, U+23BB, U+23BC, U+23BD.  Linux now uses the
78new values.
79
80[v1.2]: The following characters have been added to represent common
81keyboard symbols that are unlikely to ever be added to Unicode proper
82since they are horribly vendor-specific.  This, of course, is an
83excellent example of horrible design.
84
85====== ======================================
86U+F810 KEYBOARD SYMBOL FLYING FLAG
87U+F811 KEYBOARD SYMBOL PULLDOWN MENU
88U+F812 KEYBOARD SYMBOL OPEN APPLE
89U+F813 KEYBOARD SYMBOL SOLID APPLE
90====== ======================================
91
92Klingon language support
93------------------------
94
95In 1996, Linux was the first operating system in the world to add
96support for the artificial language Klingon, created by Marc Okrand
97for the "Star Trek" television series.	This encoding was later
98adopted by the ConScript Unicode Registry and proposed (but ultimately
99rejected) for inclusion in Unicode Plane 1.  Thus, it remains as a
100Linux/CSUR private assignment in the Linux Zone.
101
102This encoding has been endorsed by the Klingon Language Institute.
103For more information, contact them at:
104
105	http://www.kli.org/
106
107Since the characters in the beginning of the Linux CZ have been more
108of the dingbats/symbols/forms type and this is a language, I have
109located it at the end, on a 16-cell boundary in keeping with standard
110Unicode practice.
111
112.. note::
113
114  This range is now officially managed by the ConScript Unicode
115  Registry.  The normative reference is at:
116
117	http://www.evertype.com/standards/csur/klingon.html
118
119Klingon has an alphabet of 26 characters, a positional numeric writing
120system with 10 digits, and is written left-to-right, top-to-bottom.
121
122Several glyph forms for the Klingon alphabet have been proposed.
123However, since the set of symbols appear to be consistent throughout,
124with only the actual shapes being different, in keeping with standard
125Unicode practice these differences are considered font variants.
126
127======	=======================================================
128U+F8D0	KLINGON LETTER A
129U+F8D1	KLINGON LETTER B
130U+F8D2	KLINGON LETTER CH
131U+F8D3	KLINGON LETTER D
132U+F8D4	KLINGON LETTER E
133U+F8D5	KLINGON LETTER GH
134U+F8D6	KLINGON LETTER H
135U+F8D7	KLINGON LETTER I
136U+F8D8	KLINGON LETTER J
137U+F8D9	KLINGON LETTER L
138U+F8DA	KLINGON LETTER M
139U+F8DB	KLINGON LETTER N
140U+F8DC	KLINGON LETTER NG
141U+F8DD	KLINGON LETTER O
142U+F8DE	KLINGON LETTER P
143U+F8DF	KLINGON LETTER Q
144	- Written <q> in standard Okrand Latin transliteration
145U+F8E0	KLINGON LETTER QH
146	- Written <Q> in standard Okrand Latin transliteration
147U+F8E1	KLINGON LETTER R
148U+F8E2	KLINGON LETTER S
149U+F8E3	KLINGON LETTER T
150U+F8E4	KLINGON LETTER TLH
151U+F8E5	KLINGON LETTER U
152U+F8E6	KLINGON LETTER V
153U+F8E7	KLINGON LETTER W
154U+F8E8	KLINGON LETTER Y
155U+F8E9	KLINGON LETTER GLOTTAL STOP
156
157U+F8F0	KLINGON DIGIT ZERO
158U+F8F1	KLINGON DIGIT ONE
159U+F8F2	KLINGON DIGIT TWO
160U+F8F3	KLINGON DIGIT THREE
161U+F8F4	KLINGON DIGIT FOUR
162U+F8F5	KLINGON DIGIT FIVE
163U+F8F6	KLINGON DIGIT SIX
164U+F8F7	KLINGON DIGIT SEVEN
165U+F8F8	KLINGON DIGIT EIGHT
166U+F8F9	KLINGON DIGIT NINE
167
168U+F8FD	KLINGON COMMA
169U+F8FE	KLINGON FULL STOP
170U+F8FF	KLINGON SYMBOL FOR EMPIRE
171======	=======================================================
172
173Other Fictional and Artificial Scripts
174--------------------------------------
175
176Since the assignment of the Klingon Linux Unicode block, a registry of
177fictional and artificial scripts has been established by John Cowan
178<jcowan@reutershealth.com> and Michael Everson <everson@evertype.com>.
179The ConScript Unicode Registry is accessible at:
180
181	  http://www.evertype.com/standards/csur/
182
183The ranges used fall at the low end of the End User Zone and can hence
184not be normatively assigned, but it is recommended that people who
185wish to encode fictional scripts use these codes, in the interest of
186interoperability.  For Klingon, CSUR has adopted the Linux encoding.
187The CSUR people are driving adding Tengwar and Cirth into Unicode
188Plane 1; the addition of Klingon to Unicode Plane 1 has been rejected
189and so the above encoding remains official.
190