.\" 2001-05-11 Markus Kuhn <mgk25@cl.cam.ac.uk>
.\" Update
.\"
-.TH UNICODE 7 2012-08-05 "GNU" "Linux Programmer's Manual"
+.TH UNICODE 7 2014-06-13 "GNU" "Linux Programmer's Manual"
.SH NAME
Unicode \- universal character set
.SH DESCRIPTION
-The international standard
-.B ISO 10646
-defines the
-.BR "Universal Character Set (UCS)" .
+The international standard ISO 10646 defines the
+Universal Character Set (UCS).
UCS contains all characters of all other character set standards.
-It also guarantees
-.BR "round-trip compatibility";
+It also guarantees "round-trip compatibility";
in other words,
conversion tables can be built such that no information is lost
when a string is converted from any other encoding to UCS and back.
systems, and more are being added.
The UCS standard (ISO 10646) describes a
-.I "31-bit character set architecture"
+31-bit character set architecture
consisting of 128 24-bit
.IR groups ,
each divided into 256 16-bit
with 256
.I column
positions, one for each character.
-Part 1 of the standard
-.RB ( "ISO 10646-1" )
+Part 1 of the standard (ISO 10646-1)
defines the first 65534 code positions (0x0000 to 0xfffd), which form
the
-.IR "Basic Multilingual Plane (BMP)" ,
-that is plane 0 in group 0.
-Part 2 of the standard
-.RB ( "ISO 10646-2" )
+.IR "Basic Multilingual Plane"
+(BMP), that is plane 0 in group 0.
+Part 2 of the standard (ISO 10646-2)
adds characters to group 0 outside the BMP in several
.I "supplementary planes"
in the range 0x10000 to 0x10ffff.
enthusiast needs.
.PP
The representation of each UCS character as a 2-byte word is referred
-to as the
-.B UCS-2
-form (only for BMP characters), whereas
-.B UCS-4
-is the representation of each character by a 4-byte word.
-In addition, there exist two encoding forms
-.B UTF-8
-for backward compatibility with ASCII processing software and
-.B UTF-16
+to as the UCS-2 form (only for BMP characters),
+whereas UCS-4 is the representation of each character by a 4-byte word.
+In addition, there exist two encoding forms UTF-8
+for backward compatibility with ASCII processing software and UTF-16
for the backward-compatible handling of non-BMP characters up to
0x10ffff by UCS-2 software.
.PP
The UCS characters 0x0000 to 0x007f are identical to those of the
-classic
-.B US-ASCII
+classic US-ASCII
character set and the characters in the range 0x0000 to 0x00ff
are identical to those in
-.BR "ISO 8859-1 Latin-1" .
+ISO 8859-1 (Latin-1).
.SS Combining characters
-Some code points in
-.B UCS
+Some code points in UCS
have been assigned to
.IR "combining characters" .
These are similar to the nonspacing accent keys on a typewriter.
of UCS:
.TP 0.9i
Level 1
-Combining characters and
-.B Hangul Jamo
+Combining characters and Hangul Jamo
(a variant encoding of the Korean script, where a Hangul syllable
glyph is coded as a triplet or pair of vovel/consonant codes) are not
supported.
Arabic, Devanagari, Malayalam).
.TP
Level 3
-All
-.B UCS
-characters are supported.
+All UCS characters are supported.
.PP
-The
-.B Unicode 3.0 Standard
-published by the
-.B Unicode Consortium
-contains exactly the
-.B UCS Basic Multilingual Plane
+The Unicode 3.0 Standard
+published by the Unicode Consortium
+contains exactly the UCS Basic Multilingual Plane
at implementation level 3, as described in ISO 10646-1:2000.
-.B Unicode 3.1
-added the supplemental planes of ISO 10646-2.
+Unicode 3.1 added the supplemental planes of ISO 10646-2.
The Unicode standard and
technical reports published by the Unicode Consortium provide much
additional information on the semantics and recommended usages of
.I wchar_t
is a signed 32-bit integer type.
Its values are always interpreted
-by the C library as
-.B UCS
+by the C library as UCS
code values (in all locales), a convention that is signaled by the GNU
C library to applications by defining the constant
.B __STDC_ISO_10646__
UCS/Unicode can be used just like ASCII in input/output streams,
terminal communication, plaintext files, filenames, and environment
-variables in the ASCII compatible
-.B UTF-8
-multibyte encoding.
+variables in the ASCII compatible UTF-8 multibyte encoding.
To signal the use of UTF-8 as the character
encoding to all applications, a suitable
.I locale
tells, how many positions (0\(en2) the cursor is advanced by the
output of a character.
.PP
-Under Linux, in general only the BMP at implementation level 1 should
-be used at the moment.
-Up to two combining characters per base
-character for certain scripts (in particular Thai) are also supported
-by some UTF-8 terminal emulators and ISO 10646 fonts (level 2), but in
-general precomposed characters should be preferred where available
-(Unicode calls this
-.BR "Normalization Form C" ).
.SS Private area
-In the
-.BR BMP ,
+In the Basic Multilingual Plane,
the range 0xe000 to 0xf8ff will never be assigned to any characters by
the standard and is reserved for private usage.
For the Linux
and the Linux zone in the range 0xf000 to 0xf8ff where extensions are
coordinated among all Linux users.
The registry of the characters
-assigned to the Linux zone is currently maintained by H. Peter Anvin
-<Peter.Anvin@linux.org>.
+assigned to the Linux zone is maintained by LANANA and the registry
+itself is
+.I Documentation/unicode.txt
+in the Linux kernel sources.
.SS Literature
-.TP 0.2i
-*
+.IP * 3
Information technology \(em Universal Multiple-Octet Coded Character
Set (UCS) \(em Part 1: Architecture and Basic Multilingual Plane.
International Standard ISO/IEC 10646-1, International Organization
for Standardization, Geneva, 2000.
-This is the official specification of
-.BR UCS .
-Available as a PDF file on CD-ROM from
+This is the official specification of UCS .
+Available from
.UR http://www.iso.ch/
.UE .
-.TP
-*
+.IP *
The Unicode Standard, Version 3.0.
The Unicode Consortium, Addison-Wesley,
Reading, MA, 2000, ISBN 0-201-61633-5.
-.TP
-*
+.IP *
S. Harbison, G. Steele. C: A Reference Manual. Fourth edition,
Prentice Hall, Englewood Cliffs, 1995, ISBN 0-13-326224-3.
adds a large number of new C library functions for handling wide and
multibyte character encodings, but it does not yet cover ISO C99,
which improved wide and multibyte character support even further.
-.TP
-*
+.IP *
Unicode Technical Reports.
.RS
-.UR http://www.unicode.org\:/unicode\:/reports/
+.UR http://www.unicode.org\:/reports/
.UE
.RE
-.TP
-*
+.IP *
Markus Kuhn: UTF-8 and Unicode FAQ for UNIX/Linux.
.RS
.UR http://www.cl.cam.ac.uk\:/~mgk25\:/unicode.html
.UE
-
-Provides subscription information for the
-.I linux-utf8
-mailing list, which is the best place to look for advice on using
-Unicode under Linux.
.RE
-.TP
-*
+.IP *
Bruno Haible: Unicode HOWTO.
.RS
-.UR ftp://ftp.ilog.fr\:/pub\:/Users\:/haible\:/utf8\:/Unicode-HOWTO.html
+.UR http://www.tldp.org\:/HOWTO\:/Unicode-HOWTO.html
.UE
.RE
-.SH BUGS
-When this man page was last revised, the GNU C Library support for
-.B UTF-8
-locales was mature and XFree86 support was in an advanced state, but
-work on making applications (most notably editors) suitable for use in
-.B UTF-8
-locales was still fully in progress.
-Current general
-.B UCS
-support under Linux usually provides for CJK double-width characters
-and sometimes even simple overstriking combining characters, but
-usually does not include support for scripts with right-to-left
-writing direction or ligature substitution requirements such as
-Hebrew, Arabic, or the Indic scripts.
-These scripts are currently
-supported only in certain GUI applications (HTML viewers, word processors)
-with sophisticated text rendering engines.
.\" .SH AUTHOR
.\" Markus Kuhn <mgk25@cl.cam.ac.uk>
.SH SEE ALSO
+.BR locale (1),
.BR setlocale (3),
.BR charsets (7),
.BR utf-8 (7)
.SH COLOPHON
-This page is part of release 3.68 of the Linux
+This page is part of release 3.75 of the Linux
.I man-pages
project.
A description of the project,
OSDN Git Service
