PR target/27599

[official-gcc.git] / libjava / classpath / doc / unicode / ReadMe-2.1.1.txt

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UNICODE 2.1 CHARACTER DATABASE\r
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Copyright (c) 1991-1998 Unicode, Inc.\r
All Rights reserved.\r
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DISCLAIMER\r
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The Unicode Character Database "UNIDAT21.TXT" is provided as-is by\r
Unicode, Inc. (The Unicode Consortium). No claims are made as to fitness for any\r
particular purpose. No warranties of any kind are expressed or implied. The\r
recipient agrees to determine applicability of information provided. If this\r
file has been purchased on magnetic or optical media from Unicode, Inc.,\r
the sole remedy for any claim will be exchange of defective media within\r
90 days of receipt.\r
\r
This disclaimer is applicable for all other data files accompanying the\r
Unicode Character Database, some of which have been compiled by the\r
Unicode Consortium, and some of which have been supplied by other vendors.\r
\r
LIMITATIONS ON RIGHTS TO REDISTRIBUTE THIS DATA\r
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Recipient is granted the right to make copies in any form for internal\r
distribution and to freely use the information supplied in the creation of\r
products supporting the Unicode (TM) Standard. This file can be redistributed\r
to third parties or other organizations (whether for profit or not) as long\r
as this notice and the disclaimer notice are retained.\r
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EXPLANATORY INFORMATION\r
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The Unicode Character Database defines the default Unicode character\r
properties, and internal mappings. Particular implementations may choose to\r
override the properties and mappings that are not normative. If that is done,\r
it is up to the implementer to establish a protocol to convey that\r
information. For more information about character properties and mappings,\r
see "The Unicode Standard, Worldwide Character Encoding, Version 2.0",\r
published by Addison-Wesley. For information about other data files\r
accompanying the Unicode Character Database, see the section of the\r
Unicode Standard they were extracted from, or the explanatory readme\r
files and/or header sections with those files.\r
\r
The Unicode Character Database has been updated to reflect Version 2.1\r
of the Unicode Standard, with two additional characters added to those\r
published in Version 2.0:\r
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   U+20AC EURO SIGN\r
   U+FFFC OBJECT REPLACEMENT CHARACTER\r
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A number of corrections have also been made to case mappings or other\r
errors in the database noted since the publication of Version 2.0. And\r
a few normative bidirectional properties have been modified to reflect\r
decisions of the Unicode Technical Committee.\r
\r
The Unicode Character Database is a plain ASCII text file consisting of lines\r
containing fields terminated by semicolons. Each line represents the data for\r
one encoded character in the Unicode Standard, Version 2.1. Every encoded\r
character has a data entry, with the exception of certain special ranges, as\r
detailed below.\r
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There are five special ranges of characters that are represented only by\r
their start and end characters, since the properties in the file are uniform,\r
except for code values (which are all sequential and assigned). The names of CJK\r
ideograph characters and Hangul syllable characters are algorithmically\r
derivable. (See the Unicode Standard for more information). Surrogate\r
characters and private use characters have no names.\r
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The exact ranges represented by start and end characters are:\r
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   The CJK Ideographs Area (U+4E00 - U+9FFF)\r
   The Hangul Syllables Area (U+AC00 - U+D7A3)\r
   The Surrogates Area (U+D800 - U+DFFF)\r
   The Private Use Area (U+E000 - U+F8FF)\r
   CJK Compatibility Ideographs (U+F900 - U+FAFF)\r
\r
The following table describes the format and meaning of each field in a\r
data entry in the Unicode Character Database. Fields which contain\r
normative information are so indicated.\r
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Field   Explanation\r
-----   -----------\r
\r
  0     Code value in 4-digit hexadecimal format.\r
        This field is normative.\r
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  1     Unicode 2.1 Character Name. These names match exactly the\r
        names published in Chapter 7 of the Unicode Standard, Version\r
        2.0, except for the two additional characters.\r
        This field is normative.\r
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  2     General Category. This is a useful breakdown into various "character\r
        types" which can be used as a default categorization in implementations.\r
        Some of the values are normative, and some are informative.\r
        See below for a brief explanation.\r
\r
  3     Canonical Combining Classes. The classes used for the\r
        Canonical Ordering Algorithm in the Unicode Standard. These\r
        classes are also printed in Chapter 4 of the Unicode Standard.\r
        This field is normative. See below for a brief explanation.\r
\r
  4     Bidirectional Category. See the list below for an explanation of the\r
        abbreviations used in this field. These are the categories required\r
        by the Bidirectional Behavior Algorithm in the Unicode Standard.\r
        These categories are summarized in Chapter 4 of the Unicode Standard.\r
        This field is normative.\r
\r
  5     Character Decomposition. In the Unicode Standard, not all of\r
        the decompositions are full decompositions. Recursive\r
        application of look-up for decompositions will, in all cases, lead to\r
        a maximal decomposition. The decompositions match exactly the\r
        decompositions published with the character names in Chapter 7\r
        of the Unicode Standard. This field is normative.\r
\r
  6     Decimal digit value. This is a numeric field. If the character\r
        has the decimal digit property, as specified in Chapter 4 of\r
        the Unicode Standard, the value of that digit is represented\r
        with an integer value in this field. This field is normative.\r
\r
  7     Digit value. This is a numeric field. If the character represents a\r
        digit, not necessarily a decimal digit, the value is here. This\r
        covers digits which do not form decimal radix forms, such as the\r
        compatibility superscript digits. This field is informative.\r
\r
  8     Numeric value. This is a numeric field. If the character has the\r
        numeric property, as specified in Chapter 4 of the Unicode\r
        Standard, the value of that character is represented with an\r
        integer or rational number in this field. This includes fractions as,\r
        e.g., "1/5" for U+2155 VULGAR FRACTION ONE FIFTH.\r
        Also included are numerical values for compatibility characters\r
        such as circled numbers. This field is normative.\r
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  9     If the characters has been identified as a "mirrored" character in\r
        bidirectional text, this field has the value "Y"; otherwise "N".\r
        The list of mirrored characters is also printed in Chapter 4 of\r
        the Unicode Standard. This field is normative.\r
\r
 10     Unicode 1.0 Name. This is the old name as published in Unicode 1.0.\r
        This name is only provided when it is significantly different from\r
        the Unicode 2.1 name for the character. This field is informative.\r
\r
 11     10646 Comment field. This field is informative.\r
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 12     Upper case equivalent mapping. If a character is part of an\r
        alphabet with case distinctions, and has an upper case equivalent,\r
        then the upper case equivalent is in this field. See the explanation\r
        below on case distinctions. These mappings are always one-to-one,\r
        not one-to-many or many-to-one. This field is informative.\r
\r
 13     Lower case equivalent mapping. Similar to 12. This field is informative.\r
\r
 14     Title case equivalent mapping. Similar to 12. This field is informative.\r
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GENERAL CATEGORY\r
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The values in this field are abbreviations for the following. Some of the\r
values are normative, and some are informative. For more information, see\r
the Unicode Standard. Note: the standard does not assign information to\r
control characters (except for TAB in the Bidirectonal Algorithm).\r
Implementations will generally also assign categories to certain control\r
characters, notably CR and LF, according to platform conventions.\r
\r
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Normative\r
    Mn = Mark, Non-Spacing\r
    Mc = Mark, Spacing Combining\r
    Me = Mark, Enclosing\r
\r
    Nd = Number, Decimal Digit\r
    Nl = Number, Letter\r
    No = Number, Other\r
\r
    Zs = Separator, Space\r
    Zl = Separator, Line\r
    Zp = Separator, Paragraph\r
\r
    Cc = Other, Control\r
    Cf = Other, Format\r
    Cs = Other, Surrogate\r
    Co = Other, Private Use\r
    Cn = Other, Not Assigned\r
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Informative\r
    Lu = Letter, Uppercase\r
    Ll = Letter, Lowercase\r
    Lt = Letter, Titlecase\r
    Lm = Letter, Modifier\r
    Lo = Letter, Other\r
\r
    Pc = Punctuation, Connector\r
    Pd = Punctuation, Dash\r
    Ps = Punctuation, Open\r
    Pe = Punctuation, Close\r
    Po = Punctuation, Other\r
\r
    Sm = Symbol, Math\r
    Sc = Symbol, Currency\r
    Sk = Symbol, Modifier\r
    So = Symbol, Other\r
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BIDIRECTIONAL PROPERTIES\r
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Please refer to the Unicode Standard for an explanation of the algorithm for\r
Bidirectional Behavior and an explanation of the sigificance of these categories.\r
These values are normative.\r
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Strong types:\r
        L       Left-Right; Most alphabetic, syllabic, and logographic\r
                        characters (e.g., CJK ideographs)\r
        R       Right-Left; Arabic, Hebrew, and\r
                        punctuation specific to those scripts\r
Weak types:\r
        EN      European Number\r
        ES      European Number Separator\r
        ET      European Number Terminator\r
        AN      Arabic Number\r
        CS      Common Number Separator\r
\r
Separators:\r
        B       Block Separator\r
        S       Segment Separator\r
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Neutrals:\r
        WS      Whitespace\r
        ON      Other Neutrals ; All other characters: punctuation, symbols\r
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CHARACTER DECOMPOSITION TAGS\r
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The decomposition is a normative property of a character. The tags supplied\r
with certain decompositions generally indicate formatting information.\r
Where no such tag is given, the decomposition is designated as canonical.\r
Conversely, the presence of a formatting tag also indicates\r
that the decomposition is a compatibility decomposition and not a canonical\r
decomposition. In the absence of other formatting information in a\r
compatibility decomposition, the tag <compat> is used to distinguish it from\r
canonical decompositions.\r
\r
In some instances a canonical decomposition or a compatibility decomposition\r
may consist of a single character. For a canonical decomposition, this\r
indicates that the character is a canonical equivalent of another single\r
character. For a compatibility decomposition, this indicates that the\r
character is a compatibility equivalent of another single character.\r
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The compatibility formatting tags used are:\r
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        <font>          A font variant (e.g. a blackletter form).\r
        <noBreak>       A no-break version of a space or hyphen.\r
        <initial>       An initial presentation form (Arabic).\r
        <medial>        A medial presentation form (Arabic).\r
        <final>         A final presentation form (Arabic).\r
        <isolated>      An isolated presentation form (Arabic).\r
        <circle>        An encircled form.\r
        <super>         A superscript form.\r
        <sub>           A subscript form.\r
        <vertical>      A vertical layout presentation form.\r
        <wide>          A wide (or zenkaku) compatibility character.\r
        <narrow>        A narrow (or hankaku) compatibility character.\r
        <small>         A small variant form (CNS compatibility).\r
        <square>        A CJK squared font variant.\r
        <fraction>      A vulgar fraction form.\r
        <compat>        Otherwise unspecified compatibility character.\r
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CANONICAL COMBINING CLASSES\r
\r
  0: Spacing, enclosing, reordrant, and surrounding\r
  1: Overlays and interior\r
  6: Tibetan subjoined Letters\r
  7: Nuktas\r
  8: Hiragana/Katakana voiced marks\r
  9: Viramas\r
 10: Start of fixed position classes\r
199: End of fixed position classes\r
200: Below left attached\r
202: Below attached\r
204: Below right attached\r
208: Left attached (reordrant around single base character)\r
210: Right attached\r
212: Above left attached\r
214: Above attached\r
216: Above right attached\r
218: Below left\r
220: Below\r
222: Below right\r
224: Left (reordrant around single base character)\r
226: Right\r
228: Above left\r
230: Above\r
232: Above right\r
234: Double above\r
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Note: some of the combining classes in this list do not currently have\r
members but are specified here for completeness.\r
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CASE MAPPINGS\r
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In addition to uppercase and lowercase, because of the inclusion of certain\r
composite characters for compatibility, such as "01F1;LATIN CAPITAL LETTER\r
DZ", there is a third case, called titlecase, which is used where the first\r
character of a word is to be capitalized (e.g. UPPERCASE, Titlecase,\r
lowercase). An example of such a character is "01F2;LATIN CAPITAL LETTER D\r
WITH SMALL LETTER Z".\r
\r
The uppercase, titlecase and lowercase fields are only included for characters\r
that have a single corresponding character of that type. Composite characters\r
(such as "339D;SQUARE CM") that do not have a single corresponding character\r
of that type can be cased by decomposition.\r
\r
The case mapping is an informative, default mapping. Certain languages, such\r
as Turkish, German, French, or Greek may have small deviations from the\r
default mappings listed in the Unicode Character Database.\r
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MODIFICATION HISTORY\r
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Modifications made in updating the Unicode Character Database for\r
the Unicode Standard, Version 2.1 (from Version 2.0) are:\r
* Added two characters (U+20AC and U+FFFC).\r
* Amended bidi properties for U+0026, U+002E, U+0040, U+2007.\r
* Corrected case mappings for U+018E, U+019F, U+01DD, U+0258, U+0275,\r
        U+03C2, U+1E9B.\r
* Changed combining order class for U+0F71.\r
* Corrected canonical decompositions for U+0F73, U+1FBE.\r
* Changed decomposition for U+FB1F from compatibility to canonical.\r
* Added compatibility decompositions for U+FBE8, U+FBE9, U+FBF9..U+FBFB.\r
* Corrected compatibility decompositions for U+2469, U+246A, U+3358.\r
\r
\r
Some of the modifications made in updating the Unicode Character Database\r
for the Unicode Standard, Version 2.0 are:\r
* Fixed decompositions with TONOS to use correct NSM: 030D.\r
* Removed old Hangul Syllables; mapping to new characters are\r
        in a separate table.\r
* Marked compability decompositions with additional tags.\r
* Changed old tag names for clarity.\r
* Revision of decompositions to use first-level decomposition, instead\r
        of maximal decomposition.\r
* Correction of all known errors in decompositions from earlier versions.\r
* Added control code names (as old Unicode names).\r
* Added Hangul Jamo decompositions.\r
* Added Number category to match properties list in book.\r
* Fixed categories of Koranic Arabic marks.\r
* Fixed categories of precomposed characters to match decomposition where possible.\r
* Added Hebrew cantillation marks and the Tibetan script.\r
* Added place holders for ranges such as CJK Ideographic Area and the\r
        Private Use Area.\r
* Added categories Me, Sk, Pc, Nl, Cs, Cf, and rectified a number of mistakes in the\r
        database.\r