FreeBSD/Linux Kernel Cross Reference
sys/Documentation/unicode.txt

     The Linux kernel code has been rewritten to use Unicode to map
     characters to fonts.  By downloading a single Unicode-to-font table,
     both the eight-bit character sets and UTF-8 mode are changed to use
     the font as indicated.
     
     This changes the semantics of the eight-bit character tables subtly.
     The four character tables are now:
     
     Map symbol      Map name                        Escape code (G0)
    
    LAT1_MAP        Latin-1 (ISO 8859-1)            ESC ( B
    GRAF_MAP        DEC VT100 pseudographics        ESC ( 0
    IBMPC_MAP       IBM code page 437               ESC ( U
    USER_MAP        User defined                    ESC ( K
    
    In particular, ESC ( U is no longer "straight to font", since the font
    might be completely different than the IBM character set.  This
    permits for example the use of block graphics even with a Latin-1 font
    loaded.
    
    In accordance with the Unicode standard/ISO 10646 the range U+F000 to
    U+F8FF has been reserved for OS-wide allocation (the Unicode Standard
    refers to this as a "Corporate Zone", since this is inaccurate for
    Linux we call it the "Linux Zone").  U+F000 was picked as the starting
    point since it lets the direct-mapping area start on a large power of
    two (in case 1024- or 2048-character fonts ever become necessary).
    This leaves U+E000 to U+EFFF as End User Zone.
    
    The Unicodes in the range U+F000 to U+F1FF have been hard-coded to map
    directly to the loaded font, bypassing the translation table.  The
    user-defined map now defaults to U+F000 to U+F1FF, emulating the
    previous behaviour.  This range may expand in the future should it be
    warranted.
    
    Actual characters assigned in the Linux Zone
    --------------------------------------------
    
    In addition, the following characters not present in Unicode 1.1.4 (at
    least, I have not found them!) have been defined; these are used by
    the DEC VT graphics map:
    
    U+F800 DEC VT GRAPHICS HORIZONTAL LINE SCAN 1
    U+F801 DEC VT GRAPHICS HORIZONTAL LINE SCAN 3
    U+F803 DEC VT GRAPHICS HORIZONTAL LINE SCAN 7
    U+F804 DEC VT GRAPHICS HORIZONTAL LINE SCAN 9
    
    The DEC VT220 uses a 6x10 character matrix, and these characters form
    a smooth progression in the DEC VT graphics character set.  I have
    omitted the scan 5 line, since it is also used as a block-graphics
    character, and hence has been coded as U+2500 FORMS LIGHT HORIZONTAL.
    However, I left U+F802 blank should the need arise.  
    
    Klingon language support
    ------------------------
    
    Unfortunately, Unicode/ISO 10646 does not allocate code points for the
    language Klingon, probably fearing the potential code point explosion
    if many fictional languages were submitted for inclusion.  There are
    also political reasons (the Japanese, for example, are not too happy
    about the whole 16-bit concept to begin with.)  However, with Linux
    being a hacker-driven OS it seems this is a brilliant linguistic hack
    worth supporting.  Hence I have chosen to add it to the list in the
    Linux Zone.
    
    Several glyph forms for the Klingon alphabet have been proposed.
    However, since the set of symbols appear to be consistent throughout,
    with only the actual shapes being different, in keeping with standard
    Unicode practice these differences are considered font variants.
    
    Klingon has an alphabet of 26 characters, a positional numeric writing
    system with 10 digits, and is written left-to-right, top-to-bottom.
    Punctuation appears to be only used in Latin transliteration; it
    appears customary to write each sentence on its own line, and
    centered.  Space has been reserved for punctuation should it prove
    necessary.
    
    This encoding has been endorsed by the Klingon Language Institute.
    For more information, contact them at:
    
            http://www.kli.org/
    
    Since the characters in the beginning of the Linux CZ have been more
    of the dingbats/symbols/forms type and this is a language, I have
    located it at the end, on a 16-cell boundary in keeping with standard
    Unicode practice.
    
    U+F8D0  KLINGON LETTER A
    U+F8D1  KLINGON LETTER B
    U+F8D2  KLINGON LETTER CH
    U+F8D3  KLINGON LETTER D
    U+F8D4  KLINGON LETTER E
    U+F8D5  KLINGON LETTER GH
    U+F8D6  KLINGON LETTER H
    U+F8D7  KLINGON LETTER I
    U+F8D8  KLINGON LETTER J
    U+F8D9  KLINGON LETTER L
    U+F8DA  KLINGON LETTER M
    U+F8DB  KLINGON LETTER N
    U+F8DC  KLINGON LETTER NG
   U+F8DD  KLINGON LETTER O
   U+F8DE  KLINGON LETTER P
   U+F8DF  KLINGON LETTER Q
           - Written <q> in standard Okrand Latin transliteration
   U+F8E0  KLINGON LETTER QH
           - Written <Q> in standard Okrand Latin transliteration
   U+F8E1  KLINGON LETTER R
   U+F8E2  KLINGON LETTER S
   U+F8E3  KLINGON LETTER T
   U+F8E4  KLINGON LETTER TLH
   U+F8E5  KLINGON LETTER U
   U+F8E6  KLINGON LETTER V
   U+F8E7  KLINGON LETTER W
   U+F8E8  KLINGON LETTER Y
   U+F8E9  KLINGON LETTER GLOTTAL STOP
   
   U+F8F0  KLINGON DIGIT ZERO
   U+F8F1  KLINGON DIGIT ONE
   U+F8F2  KLINGON DIGIT TWO
   U+F8F3  KLINGON DIGIT THREE
   U+F8F4  KLINGON DIGIT FOUR
   U+F8F5  KLINGON DIGIT FIVE
   U+F8F6  KLINGON DIGIT SIX
   U+F8F7  KLINGON DIGIT SEVEN
   U+F8F8  KLINGON DIGIT EIGHT
   U+F8F9  KLINGON DIGIT NINE
   
   Other Fictional and Artificial Scripts
   --------------------------------------
   
   Since the assignment of the Klingon Linux Unicode block, a registry of
   fictional and artificial scripts has been established by John Cowan,
   <cowan@ccil.org>.  The ConScript Unicode Registry is accessible at
   http://locke.ccil.org/~cowan/csur/; the ranges used fall at the bottom
   of the End User Zone and can hence not be normatively assigned, but it
   is recommended that people who wish to encode fictional scripts use
   these codes, in the interest of interoperability.  For Klingon, CSUR
   has adopted the Linux encoding.
   
           H. Peter Anvin <hpa@zytor.com>

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