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5 .\" Paul Borman at Krystal Technologies.
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36 .Nd "UTF-8, a transformation format of ISO 10646"
43 encoding represents UCS-4 characters as a sequence of octets, using
44 between 1 and 6 for each character.
45 It is backwards compatible with
47 so 0x00-0x7f refer to the
50 The multibyte encoding of
53 consist entirely of bytes whose high order bit is set.
55 encoding is represented by the following table:
57 [0x00000000 - 0x0000007f] [00000000.0bbbbbbb] -> 0bbbbbbb
58 [0x00000080 - 0x000007ff] [00000bbb.bbbbbbbb] -> 110bbbbb, 10bbbbbb
59 [0x00000800 - 0x0000ffff] [bbbbbbbb.bbbbbbbb] ->
60 1110bbbb, 10bbbbbb, 10bbbbbb
61 [0x00010000 - 0x001fffff] [00000000.000bbbbb.bbbbbbbb.bbbbbbbb] ->
62 11110bbb, 10bbbbbb, 10bbbbbb, 10bbbbbb
63 [0x00200000 - 0x03ffffff] [000000bb.bbbbbbbb.bbbbbbbb.bbbbbbbb] ->
64 111110bb, 10bbbbbb, 10bbbbbb, 10bbbbbb, 10bbbbbb
65 [0x04000000 - 0x7fffffff] [0bbbbbbb.bbbbbbbb.bbbbbbbb.bbbbbbbb] ->
66 1111110b, 10bbbbbb, 10bbbbbb, 10bbbbbb, 10bbbbbb, 10bbbbbb
69 If more than a single representation of a value exists (for example,
70 0x00; 0xC0 0x80; 0xE0 0x80 0x80) the shortest representation is always
72 Longer ones are detected as an error as they pose a potential
73 security risk, and destroy the 1:1 character:octet sequence mapping.
80 .%J "Proceedings of the Winter 1993 USENIX Technical Conference"
81 .%Q "USENIX Association"
86 .%T "UTF-8, a transformation format of ISO 10646"
91 .%Q "The Unicode Consortium"
92 .%T "The Unicode Standard, Version 3.0"
94 .%O "as amended by the Unicode Standard Annex #27: Unicode 3.1 and by the Unicode Standard Annex #28: Unicode 3.2"
99 encoding is compatible with RFC 2279 and Unicode 3.2.