X Locale Database Specification

An X Locale Database contains the subset of a user's environment that depends on language, in X Window System. It is made up from one or more categories. Each category consists of some classes and sub-classes.

It is provided as a plain ASCII text file, so a user can change its contents easily. It allows a user to customize the behavior of internationalized portion of Xlib without changing Xlib itself.

This document describes;

Since it is hard to define the set of required information for all platforms, only the flexible database format is defined. The available entries in database are implementation dependent.

The X Locale Database contains one or more category definitions. This section describes the format of each category definition.

The category definition consists of one or more class definitions. Each class definition has a pair of class name and class value, or has several subclasses which are enclosed by the left brace ({) and the right brace (}).

Comments can be placed by using the number sign character (#). Putting the number sign character on the top of the line indicates that the entire line is comment. Also, putting any whitespace character followed by the number sign character indicates that a part of the line (from the number sign to the end of the line) is comment. A line can be continued by placing backslash (\) character as the last character on the line; this continuation character will be discarded from the input. Comment lines cannot be continued on a subsequent line using an escaped new line character.

X Locale Database only accepts XPCS, the X Portable Character Set. The reserved symbols are; the quotation mark("), the number sign (#), the semicolon(;), the backslash(\), the left brace({) and the right brace(}).

The format of category definition is;

Elements separated by vertical bar (|) are alternatives. Curly braces ({...}) indicate zero or more repetitions of the enclosed elements. Square brackets ([...]) indicate that the enclosed element is optional. Quotes ("...") are used around literal characters.

The backslash, which is not the top character of the NumericString, is recognized as an escape character, so that the next one character is treated as a literal character. For example, the two-character sequence, ""\"""(the backslash followed by the quotation mark) is recognized and replaced with a quotation mark character. Any whitespace character, that is not the Delimiter, unquoted and unescaped, is ignored.

The available categories and classes depend on implementation, because different platform will require different information set. For example, some platform have system locale but some platform don't. Furthermore, there might be a difference in functionality even if the platform has system locale.

In current sample implementation, categories listed below are available.

The XLC_FONTSET category defines the XFontSet relative information. It contains the CHARSET_REGISTRY-CHARSET_ENCODING name and character mapping side (GL, GR, etc), and is used in Output Method (OM).

The XLC_XLOCALE category defines character classification, conversion and other character attributes.

The following is sample X Locale Database file.

#  XLocale Database Sample for ja_JP.euc
#

#
#      XLC_FONTSET category
#
XLC_FONTSET
#      fs0 class (7 bit ASCII)
fs0     {
        charset              ISO8859-1:GL
        font                 ISO8859-1:GL; JISX0201.1976-0:GL
}
#      fs1 class (Kanji)
fs1     {
        charset              JISX0208.1983-0:GL
        font                 JISX0208.1983-0:GL
}
#      fs2 class (Half Kana)
fs2     {
        charset              JISX0201.1976-0:GR
        font                 JISX0201.1976-0:GR
}
#      fs3 class (User Defined Character)
# fs3     {
#        charset             JISX0212.1990-0:GL
#        font                JISX0212.1990-0:GL
# }
END XLC_FONTSET

#
#      XLC_XLOCALE category
#
XLC_XLOCALE

encoding_name             ja.euc
mb_cur_max                3
state_depend_encoding     False

wc_encoding_mask          \x00008080
wc_shift_bits             8

#      cs0 class
cs0     {
        side                 GL:Default
        length               1
        wc_encoding          \x00000000
        ct_encoding          ISO8859-1:GL; JISX0201.1976-0:GL
}
#      cs1 class
cs1     {
        side                 GR:Default
        length               2

        wc_encoding          \x00008080

        ct_encoding          JISX0208.1983-0:GL; JISX0208.1983-0:GR;\
                             JISX0208.1983-1:GL; JISX0208.1983-1:GR
}

#      cs2 class
cs2     {
        side                 GR
        length               1
        mb_encoding          <SS> \x8e

        wc_encoding          \x00000080

        ct_encoding          JISX0201.1976-0:GR
}

#      cs3 class
# cs3     {
#         side               GL
#         length             2
#         mb_encoding        <SS> \x8f
# #if HasWChar32
#         wc_encoding        \x20000000
# #else
#         wc_encoding        \x00008000
# #endif
#         ct_encoding        JISX0212.1990-0:GL; JISX0212.1990-0:GR
# }

END XLC_XLOCALE

[1] ISO/IEC 9899:1990 C Language Standard

[2] X Logical Font Descriptions