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.\" $NetBSD: nls.7,v 1.13 2007/03/02 20:28:54 wiz Exp $
.\" Copyright (c) 2003 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Gregory McGarry.
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.Dd February 21, 2007
.Dt NLS 7
.Nd Native Language Support Overview
Native Language Support (NLS) provides commands for a single
worldwide operating system base.
An internationalized system has no built-in assumptions or dependencies
on language-specific or cultural-specific conventions such as:
.Bl -bullet -offset indent -compact
Character comparison rules
Character collation order
Numeric and monetary formatting
Date and time formatting
All information pertaining to cultural conventions and language is
obtained at program run time.
.Dq i18n )
refers to the operation by which system software is developed to support
multiple cultural-specific and language-specific conventions.
This is a generalization process by which the system is untied from
calling only English strings or other English-specific conventions.
.Dq l10n )
refers to the operations by which the user environment is customized to
handle its input and output appropriate for specific language and cultural
This is a specialization process, by which generic methods already
implemented in an internationalized system are used in specific ways.
The formal description of cultural conventions for some country, together
with all associated translations targeted to the native language, is
.Dq locale .
provides extensive support to programmers and system developers to
enable internationalized software to be developed.
also supplies a large variety of locales for system localization.
.Ss Localization of Information
All locale information is accessible to programs at run time so that
data is processed and displayed correctly for specific cultural
conventions and language.
A locale is divided into categories.
A category is a group of language-specific and culture-specific conventions
as outlined in the list above.
ISO C specifies the following six standard categories supported by
.Bl -tag -compact -width LC_MONETARYXX
.It Ev LC_COLLATE
string-collation order information
.It Ev LC_CTYPE
character classification, case conversion, and other character attributes
.It Ev LC_MESSAGES
the format for affirmative and negative responses
.It Ev LC_MONETARY
rules and symbols for formatting monetary numeric information
.It Ev LC_NUMERIC
rules and symbols for formatting nonmonetary numeric information
.It Ev LC_TIME
rules and symbols for formatting time and date information
Localization of the system is achieved by setting appropriate values
in environment variables to identify which locale should be used.
The environment variables have the same names as their respective
.Ev LANG ,
.Ev LC_ALL ,
environment variables are used.
environment variable specifies a colon-separated list of directory names
where the message catalog files of the NLS database are located.
environment variables also determine the current locale.
The values of these environment variables contains a string format as:
Valid values for the language field come from the ISO639 standard which
defines two-character codes for many languages.
Some common language codes are:
.ta \w'SERBO-CROATIAN'u+2n +\w'DE'u+5n +\w'OCEANIC/INDONESIAN'u+2nC
\fILanguage Name\fP \fICode\fP \fILanguage Family\fP
.ta \w'SERBO-CROATIAN'u+2n +\w'DE'u+5n +\w'OCEANIC/INDONESIAN'u+2nC
ABKHAZIAN AB IBERO-CAUCASIAN
AFAN (OROMO) OM HAMITIC
AFAR AA HAMITIC
AFRIKAANS AF GERMANIC
ALBANIAN SQ INDO-EUROPEAN (OTHER)
AMHARIC AM SEMITIC
ARABIC AR SEMITIC
ARMENIAN HY INDO-EUROPEAN (OTHER)
ASSAMESE AS INDIAN
AYMARA AY AMERINDIAN
AZERBAIJANI AZ TURKIC/ALTAIC
BASHKIR BA TURKIC/ALTAIC
BASQUE EU BASQUE
BENGALI BN INDIAN
BHUTANI DZ ASIAN
BIHARI BH INDIAN
BRETON BR CELTIC
BULGARIAN BG SLAVIC
BURMESE MY ASIAN
BYELORUSSIAN BE SLAVIC
CAMBODIAN KM ASIAN
CATALAN CA ROMANCE
CHINESE ZH ASIAN
CORSICAN CO ROMANCE
CROATIAN HR SLAVIC
CZECH CS SLAVIC
DANISH DA GERMANIC
DUTCH NL GERMANIC
ENGLISH EN GERMANIC
ESPERANTO EO INTERNATIONAL AUX.
ESTONIAN ET FINNO-UGRIC
FAROESE FO GERMANIC
FIJI FJ OCEANIC/INDONESIAN
FINNISH FI FINNO-UGRIC
FRENCH FR ROMANCE
FRISIAN FY GERMANIC
GALICIAN GL ROMANCE
GEORGIAN KA IBERO-CAUCASIAN
GERMAN DE GERMANIC
GREEK EL LATIN/GREEK
GREENLANDIC KL ESKIMO
GUARANI GN AMERINDIAN
GUJARATI GU INDIAN
HAUSA HA NEGRO-AFRICAN
HEBREW HE SEMITIC
HINDI HI INDIAN
HUNGARIAN HU FINNO-UGRIC
ICELANDIC IS GERMANIC
INDONESIAN ID OCEANIC/INDONESIAN
INTERLINGUA IA INTERNATIONAL AUX.
INTERLINGUE IE INTERNATIONAL AUX.
INUPIAK IK ESKIMO
IRISH GA CELTIC
ITALIAN IT ROMANCE
JAPANESE JA ASIAN
JAVANESE JV OCEANIC/INDONESIAN
KANNADA KN DRAVIDIAN
KASHMIRI KS INDIAN
KAZAKH KK TURKIC/ALTAIC
KINYARWANDA RW NEGRO-AFRICAN
KIRGHIZ KY TURKIC/ALTAIC
KURUNDI RN NEGRO-AFRICAN
KOREAN KO ASIAN
KURDISH KU IRANIAN
LAOTHIAN LO ASIAN
LATIN LA LATIN/GREEK
LATVIAN LV BALTIC
LINGALA LN NEGRO-AFRICAN
LITHUANIAN LT BALTIC
MACEDONIAN MK SLAVIC
MALAGASY MG OCEANIC/INDONESIAN
MALAY MS OCEANIC/INDONESIAN
MALAYALAM ML DRAVIDIAN
MALTESE MT SEMITIC
MAORI MI OCEANIC/INDONESIAN
MARATHI MR INDIAN
MOLDAVIAN MO ROMANCE
NEPALI NE INDIAN
NORWEGIAN NO GERMANIC
OCCITAN OC ROMANCE
ORIYA OR INDIAN
PASHTO PS IRANIAN
PERSIAN (farsi) FA IRANIAN
POLISH PL SLAVIC
PORTUGUESE PT ROMANCE
PUNJABI PA INDIAN
QUECHUA QU AMERINDIAN
RHAETO-ROMANCE RM ROMANCE
ROMANIAN RO ROMANCE
RUSSIAN RU SLAVIC
SAMOAN SM OCEANIC/INDONESIAN
SANGHO SG NEGRO-AFRICAN
SANSKRIT SA INDIAN
SCOTS GAELIC GD CELTIC
SERBIAN SR SLAVIC
SERBO-CROATIAN SH SLAVIC
SESOTHO ST NEGRO-AFRICAN
SETSWANA TN NEGRO-AFRICAN
SHONA SN NEGRO-AFRICAN
SINDHI SD INDIAN
SINGHALESE SI INDIAN
SISWATI SS NEGRO-AFRICAN
SLOVAK SK SLAVIC
SLOVENIAN SL SLAVIC
SOMALI SO HAMITIC
SPANISH ES ROMANCE
SUNDANESE SU OCEANIC/INDONESIAN
SWAHILI SW NEGRO-AFRICAN
SWEDISH SV GERMANIC
TAGALOG TL OCEANIC/INDONESIAN
TAJIK TG IRANIAN
TAMIL TA DRAVIDIAN
TATAR TT TURKIC/ALTAIC
TELUGU TE DRAVIDIAN
THAI TH ASIAN
TIBETAN BO ASIAN
TIGRINYA TI SEMITIC
TONGA TO OCEANIC/INDONESIAN
TSONGA TS NEGRO-AFRICAN
TURKISH TR TURKIC/ALTAIC
TURKMEN TK TURKIC/ALTAIC
TWI TW NEGRO-AFRICAN
UKRAINIAN UK SLAVIC
URDU UR INDIAN
UZBEK UZ TURKIC/ALTAIC
VIETNAMESE VI ASIAN
VOLAPUK VO INTERNATIONAL AUX.
WELSH CY CELTIC
WOLOF WO NEGRO-AFRICAN
XHOSA XH NEGRO-AFRICAN
YIDDISH YI GERMANIC
YORUBA YO NEGRO-AFRICAN
ZULU ZU NEGRO-AFRICAN
For example, the locale for the Danish language spoken in Denmark
using the ISO 8859-1 character set is da_DK.ISO8859-1.
The da stands for the Danish language and the DK stands for Denmark.
The short form of da_DK is sufficient to indicate this locale.
The environment variable settings are queried by their priority level
in the following manner:
environment variable is set, all six categories use the locale it
environment variable is not set, each individual category uses the
locale specified by its corresponding environment variable.
environment variable is not set, and a value for a particular
environment variable is not set, the value of the
environment variable specifies the default locale for all categories.
environment variable should be set in /etc/profile, since it makes it
most easy for the user to override the system default using the individual
environment variable is not set, a value for a particular
environment variable is not set, and the value of the
environment variable is not set, the locale for that specific
category defaults to the C locale.
The C or POSIX locale assumes the ASCII character set and defines
information for the six categories.
.Ss Character Sets
A character is any symbol used for the organization, control, or
representation of data.
A group of such symbols used to describe a
particular language make up a character set.
It is the encoding values in a character set that provide
the interface between the system and its input and output devices.
The following character sets are supported in
.Bl -tag -width ISO_8859_family
The American Standard Code for Information Exchange (ASCII) standard
specifies 128 Roman characters and control codes, encoded in a 7-bit
character encoding scheme.
.It ISO 8859 family
Industry-standard character sets specified by the ISO/IEC 8859
The standard is divided into 15 numbered parts, with each
part specifying broad script similarities.
Examples include Western European, Central European, Arabic, Cyrillic,
Hebrew, Greek, and Turkish.
The character sets use an 8-bit character encoding scheme which is
compatible with the ASCII character set.
The Unicode character set is the full set of known abstract characters of
all real-world scripts. It can be used in environments where multiple
scripts must be processed simultaneously.
Unicode is compatible with ISO 8859-1 (Western European) and ASCII.
Many character encoding schemes are available for Unicode, including UTF-8,
UTF-16 and UTF-32.
These encoding schemes are multi-byte encodings.
The UTF-8 encoding scheme uses 8-bit, variable-width encodings which is
compatible with ASCII.
The UTF-16 encoding scheme uses 16-bit, variable-width encodings.
The UTF-32 encoding scheme using 32-bit, fixed-width encodings.
.Ss Font Sets
A font set contains the glyphs to be displayed on the screen for a
corresponding character in a character set.
A display must support a suitable font to display a character set.
If suitable fonts are available to the X server, then X clients can
include support for different character sets.
.Xr xterm 1
includes support for Unicode with UTF-8 encoding.
.Xr xfd 1
is useful for displaying all the characters in an X font.
.Xr wscons 4
console provides support for loading fonts using the
.Xr wsfontload 8
Currently, only fonts for the ISO8859-1 family of character sets are
.Ss Internationalization for Programmers
To facilitate translations of messages into various languages and to
make the translated messages available to the program based on a
user's locale, it is necessary to keep messages separate from the
programs and provide them in the form of message catalogs that a
program can access at run time.
Access to locale information is provided through the
.Xr setlocale 3
.Xr nl_langinfo 3
See their respective man pages for further information.
Message source files containing application messages are created by
the programmer and converted to message catalogs.
These catalogs are used by the application to retrieve and display
messages, as needed.
supports two message catalog interfaces: the X/Open
.Xr catgets 3
interface and the Uniforum
.Xr gettext 3
.Xr catgets 3
interface has the advantage that it belongs to a standard which is
Unfortunately the interface is complicated to use and
maintenance of the catalogs is difficult.
The implementation also doesn't support different character sets.
.Xr gettext 3
interface has not been standardized yet, however it is being supported
by an increasing number of systems.
It also provides many additional tools which make programming and
catalog maintenance much easier.
.Ss Support for Multi-byte Encodings
Some character sets with multi-byte encodings may be difficult to decode,
or may contain state (i.e., adjacent characters are dependent).
ISO C specifies a set of functions using 'wide characters' which can handle
multi-byte encodings properly.
The behaviour of these functions is affected
category of the current locale.
A wide character is specified in ISO C
as being a fixed number of bits wide and is stateless.
There are two types for wide characters:
.Em wint_t .
is a type which can contain one wide character and operates like 'char'
type does for one character.
can contain one wide character or WEOF (wide EOF).
There are functions that operate on
.Em wchar_t ,
and substitute for functions operating on 'char'.
.Xr wmemchr 3
.Xr towlower 3
There are some additional functions that operate on
.Em wchar_t .
.Xr wctype 3
.Xr wctrans 3
Wide characters should be used for all I/O processing which may rely
on locale-specific strings.
The two primary issues requiring special use of wide characters are:
.Bl -bullet -offset indent
All I/O is performed using multibyte characters.
Input data is converted into wide characters immediately after
reading and data for output is converted from wide characters to
multi-byte encoding immediately before writing.
Conversion is controlled by the
.Xr mbstowcs 3 ,
.Xr mbsrtowcs 3 ,
.Xr wcstombs 3 ,
.Xr wcsrtombs 3 ,
.Xr mblen 3 ,
.Xr mbrlen 3 ,
.Xr mbsinit 3 .
Wide characters are used directly for I/O, using
.Xr getwchar 3 ,
.Xr fgetwc 3 ,
.Xr getwc 3 ,
.Xr ungetwc 3 ,
.Xr fgetws 3 ,
.Xr putwchar 3 ,
.Xr fputwc 3 ,
.Xr putwc 3 ,
.Xr fputws 3 .
They are also used for formatted I/O functions for wide characters
.Xr fwscanf 3 ,
.Xr wscanf 3 ,
.Xr swscanf 3 ,
.Xr fwprintf 3 ,
.Xr wprintf 3 ,
.Xr swprintf 3 ,
.Xr vfwprintf 3 ,
.Xr vwprintf 3 ,
.Xr vswprintf 3 ,
and wide character identifier of %lc, %C, %ls, %S for conventional
formatted I/O functions.
.Sh SEE ALSO
.Xr gencat 1 ,
.Xr xfd 1 ,
.Xr xterm 1 ,
.Xr catgets 3 ,
.Xr gettext 3 ,
.Xr nl_langinfo 3 ,
.Xr setlocale 3 ,
.Xr wsfontload 8
This man page is incomplete.