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1=head1 NAME
2
07fcf8ff 3perluniintro - Perl Unicode introduction
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4
5=head1 DESCRIPTION
6
7This document gives a general idea of Unicode and how to use Unicode
8in Perl.
9
10=head2 Unicode
11
12Unicode is a character set standard with plans to cover all of the
13writing systems of the world, plus many other symbols.
14
15Unicode and ISO/IEC 10646 are coordinated standards that provide code
16points for the characters in almost all modern character set standards,
17covering more than 30 writing systems and hundreds of languages,
18including all commercially important modern languages. All characters
19in the largest Chinese, Japanese, and Korean dictionaries are also
20encoded. The standards will eventually cover almost all characters in
21more than 250 writing systems and thousands of languages.
22
23A Unicode I<character> is an abstract entity. It is not bound to any
24particular integer width, and especially not to the C language C<char>.
25Unicode is language neutral and display neutral: it doesn't encode the
26language of the text, and it doesn't define fonts or other graphical
27layout details. Unicode operates on characters and on text built from
28those characters.
29
30Unicode defines characters like C<LATIN CAPITAL LETTER A> or C<GREEK
31SMALL LETTER ALPHA>, and then unique numbers for those, hexadecimal
320x0041 or 0x03B1 for those particular characters. Such unique
33numbers are called I<code points>.
34
35The Unicode standard prefers using hexadecimal notation for the code
36points. (In case this notation, numbers like 0x0041, is unfamiliar to
37you, take a peek at a later section, L</"Hexadecimal Notation">.)
38The Unicode standard uses the notation C<U+0041 LATIN CAPITAL LETTER A>,
39which gives the hexadecimal code point, and the normative name of
40the character.
41
42Unicode also defines various I<properties> for the characters, like
43"uppercase" or "lowercase", "decimal digit", or "punctuation":
44these properties are independent of the names of the characters.
45Furthermore, various operations on the characters like uppercasing,
46lowercasing, and collating (sorting), are defined.
47
48A Unicode character consists either of a single code point, or a
49I<base character> (like C<LATIN CAPITAL LETTER A>), followed by one or
50more I<modifiers> (like C<COMBINING ACUTE ACCENT>). This sequence of
51a base character and modifiers is called a I<combining character
52sequence>.
53
54Whether to call these combining character sequences, as a whole,
55"characters" depends on your point of view. If you are a programmer, you
56probably would tend towards seeing each element in the sequences as one
57unit, one "character", but from the user viewpoint, the sequence as a
58whole is probably considered one "character", since that's probably what
59it looks like in the context of the user's language.
60
61With this "as a whole" view of characters, the number of characters is
62open-ended. But in the programmer's "one unit is one character" point of
63view, the concept of "characters" is more deterministic, and so we take
64that point of view in this document: one "character" is one Unicode
65code point, be it a base character or a combining character.
66
67For some of the combinations there are I<precomposed> characters,
68for example C<LATIN CAPITAL LETTER A WITH ACUTE> is defined as
69a single code point. These precomposed characters are, however,
70often available only for some combinations, and mainly they are
71meant to support round-trip conversions between Unicode and legacy
72standards (like the ISO 8859), and in general case the composing
73method is more extensible. To support conversion between the
74different compositions of the characters, various I<normalization
75forms> are also defined.
76
77Because of backward compatibility with legacy encodings, the "a unique
78number for every character" breaks down a bit: "at least one number
79for every character" is closer to truth. (This happens when the same
80character has been encoded in several legacy encodings.) The converse
81is also not true: not every code point has an assigned character.
82Firstly, there are unallocated code points within otherwise used
83blocks. Secondly, there are special Unicode control characters that
84do not represent true characters.
85
86A common myth about Unicode is that it would be "16-bit", that is,
870x10000 (or 65536) characters from 0x0000 to 0xFFFF. B<This is untrue.>
88Since Unicode 2.0 Unicode has been defined all the way up to 21 bits
89(0x10FFFF), and since 3.1 characters have been defined beyond 0xFFFF.
90The first 0x10000 characters are called the I<Plane 0>, or the I<Basic
91Multilingual Plane> (BMP). With the Unicode 3.1, 17 planes in all are
92defined (but nowhere near full of defined characters yet).
93
94Another myth is that the 256-character blocks have something to do
95with languages: a block per language. B<Also this is untrue.>
96The division into the blocks exists but it is almost completely
97accidental, an artifact of how the characters have been historically
98allocated. Instead, there is a concept called I<scripts>, which may
99be more useful: there is C<Latin> script, C<Greek> script, and so on.
100Scripts usually span several parts of several blocks. For further
101information see L<Unicode::UCD>.
102
103The Unicode code points are just abstract numbers. To input and
104output these abstract numbers, the numbers must be I<encoded> somehow.
105Unicode defines several I<character encoding forms>, of which I<UTF-8>
106is perhaps the most popular. UTF-8 is a variable length encoding that
107encodes Unicode characters as 1 to 6 bytes (only 4 with the currently
108defined characters). Other encodings are UTF-16 and UTF-32 and their
109big and little endian variants (UTF-8 is byteorder independent).
110The ISO/IEC 10646 defines the UCS-2 and UCS-4 encoding forms.
111
112For more information about encodings, for example to learn what
113I<surrogates> and I<byte order marks> (BOMs) are, see L<perlunicode>.
114
115=head2 Perl's Unicode Support
116
117Starting from Perl 5.6.0, Perl has had the capability of handling
118Unicode natively. The first recommended release for serious Unicode
119work is Perl 5.8.0, however. The maintenance release 5.6.1 fixed many
120of the problems of the initial implementation of Unicode, but for
121example regular expressions didn't really work with Unicode.
122
123B<Starting from Perl 5.8.0, the use of C<use utf8> is no longer
124necessary.> In earlier releases the C<utf8> pragma was used to declare
125that operations in the current block or file would be Unicode-aware.
126This model was found to be wrong, or at least clumsy: the Unicodeness
127is now carried with the data, not attached to the operations. (There
128is one remaining case where an explicit C<use utf8> is needed: if your
129Perl script is in UTF-8, you can use UTF-8 in your variable and
130subroutine names, and in your string and regular expression literals,
131by saying C<use utf8>. This is not the default because that would
132break existing scripts having legacy 8-bit data in them.)
133
134=head2 Perl's Unicode Model
135
136Perl supports both the old, pre-5.6, model of strings of eight-bit
137native bytes, and strings of Unicode characters. The principle is
138that Perl tries to keep its data as eight-bit bytes for as long as
139possible, but as soon as Unicodeness cannot be avoided, the data is
140transparently upgraded to Unicode.
141
142The internal encoding of Unicode in Perl is UTF-8. The internal
143encoding is normally hidden, however, and one need not and should not
144worry about the internal encoding at all: it is all just characters.
145
146Perl 5.8.0 will also support Unicode on EBCDIC platforms. There the
147support is somewhat harder to implement since additional conversions
148are needed at every step. Because of these difficulties the Unicode
149support won't be quite as full as in other, mainly ASCII-based,
150platforms (the Unicode support will be better than in the 5.6 series,
151which didn't work much at all for EBCDIC platform). On EBCDIC
152platforms the internal encoding form used is UTF-EBCDIC.
153
154=head2 Creating Unicode
155
156To create Unicode literals, use the C<\x{...}> notation in
157doublequoted strings:
158
159 my $smiley = "\x{263a}";
160
161Similarly for regular expression literals
162
163 $smiley =~ /\x{263a}/;
164
165At run-time you can use C<chr()>:
166
167 my $hebrew_alef = chr(0x05d0);
168
169(See L</"Further Resources"> for how to find all these numeric codes.)
170
171Naturally, C<ord()> will do the reverse: turn a character to a code point.
172
173Note that C<\x..>, C<\x{..}> and C<chr(...)> for arguments less than
1740x100 (decimal 256) will generate an eight-bit character for backward
175compatibility with older Perls. For arguments of 0x100 or more,
176Unicode will always be produced. If you want UTF-8 always, use
177C<pack("U", ...)> instead of C<\x..>, C<\x{..}>, or C<chr()>.
178
179You can also use the C<charnames> pragma to invoke characters
180by name in doublequoted strings:
181
182 use charnames ':full';
183 my $arabic_alef = "\N{ARABIC LETTER ALEF}";
184
185And, as mentioned above, you can also C<pack()> numbers into Unicode
186characters:
187
188 my $georgian_an = pack("U", 0x10a0);
189
190=head2 Handling Unicode
191
192Handling Unicode is for the most part transparent: just use the
193strings as usual. Functions like C<index()>, C<length()>, and
194C<substr()> will work on the Unicode characters; regular expressions
195will work on the Unicode characters (see L<perlunicode> and L<perlretut>).
196
197Note that Perl does B<not> consider combining character sequences
198to be characters, such for example
199
200 use charnames ':full';
201 print length("\N{LATIN CAPITAL LETTER A}\N{COMBINING ACUTE ACCENT}"), "\n";
202
203will print 2, not 1. The only exception is that regular expressions
204have C<\X> for matching a combining character sequence.
205
206When life is not quite so transparent is working with legacy
207encodings, and I/O, and certain special cases.
208
209=head2 Legacy Encodings
210
211When you combine legacy data and Unicode the legacy data needs
212to be upgraded to Unicode. Normally ISO 8859-1 (or EBCDIC, if
213applicable) is assumed. You can override this assumption by
214using the C<encoding> pragma, for example
215
216 use encoding 'latin2'; # ISO 8859-2
217
218in which case literals (string or regular expression) and chr/ord
219in your whole script are assumed to produce Unicode characters from
220ISO 8859-2 code points. Note that the matching for the encoding
221names is forgiving: instead of C<latin2> you could have said
222C<Latin 2>, or C<iso8859-2>, and so forth. With just
223
224 use encoding;
225
226first the environment variable C<PERL_ENCODING> will be consulted,
227and if that doesn't exist, ISO 8859-1 (Latin 1) will be assumed.
228
229The C<Encode> module knows about many encodings and it has interfaces
230for doing conversions between those encodings:
231
232 use Encode 'from_to';
233 from_to($data, "iso-8859-3", "utf-8"); # from legacy to utf-8
234
235=head2 Unicode I/O
236
237Normally writing out Unicode data
238
1d7919c5 239 print FH chr(0x100), "\n";
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241will print out the raw UTF-8 bytes, but you will get a warning
242out of that if you use C<-w> or C<use warnings>. To avoid the
243warning open the stream explicitly in UTF-8:
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245 open FH, ">:utf8", "file";
246
247and on already open streams use C<binmode()>:
248
249 binmode(STDOUT, ":utf8");
250
251Reading in correctly formed UTF-8 data will not magically turn
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252the data into Unicode in Perl's eyes.
253
254You can use either the C<':utf8'> I/O discipline when opening files
255
256 open(my $fh,'<:utf8', 'anything');
257 my $line_of_utf8 = <$fh>;
258
259The I/O disciplines can also be specified more flexibly with
260the C<open> pragma; see L<open>:
261
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262 use open ':utf8'; # input and output default discipline will be UTF-8
263 open X, ">file";
264 print X chr(0x100), "\n";
ba62762e 265 close X;
1d7919c5 266 open Y, "<file";
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267 printf "%#x\n", ord(<Y>); # this should print 0x100
268 close Y;
269
270With the C<open> pragma you can use the C<:locale> discipline
271
272 $ENV{LANG} = 'ru_RU.KOI8-R';
273 # the :locale will probe the locale environment variables like LANG
274 use open OUT => ':locale'; # russki parusski
275 open(O, ">koi8");
276 print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1
277 close O;
278 open(I, "<koi8");
279 printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1
280 close I;
281
282or you can also use the C<':encoding(...)'> discipline
283
284 open(my $epic,'<:encoding(iso-8859-7)','iliad.greek');
285 my $line_of_iliad = <$epic>;
286
287Both of these methods install a transparent filter on the I/O stream that
288will convert data from the specified encoding when it is read in from the
289stream. In the first example the F<anything> file is assumed to be UTF-8
290encoded Unicode, in the second example the F<iliad.greek> file is assumed
291to be ISO-8858-7 encoded Greek, but the lines read in will be in both
292cases Unicode.
293
294The L<open> pragma affects all the C<open()> calls after the pragma by
295setting default disciplines. If you want to affect only certain
296streams, use explicit disciplines directly in the C<open()> call.
297
298You can switch encodings on an already opened stream by using
299C<binmode()>, see L<perlfunc/binmode>.
300
301The C<:locale> does not currently work with C<open()> and
302C<binmode()>, only with the C<open> pragma. The C<:utf8> and
303C<:encoding(...)> do work with all of C<open()>, C<binmode()>,
304and the C<open> pragma.
305
306Similarly, you may use these I/O disciplines on input streams to
307automatically convert data from the specified encoding when it is
308written to the stream.
309
310 open(my $unicode, '<:utf8', 'japanese.uni');
311 open(my $nihongo, '>:encoding(iso2022-jp)', 'japanese.jp');
312 while (<$unicode>) { print $nihongo }
313
314The naming of encodings, both by the C<open()> and by the C<open>
315pragma, is similarly understanding as with the C<encoding> pragma:
316C<koi8-r> and C<KOI8R> will both be understood.
317
318Common encodings recognized by ISO, MIME, IANA, and various other
319standardisation organisations are recognised, for a more detailed
320list see L<Encode>.
321
322C<read()> reads characters and returns the number of characters.
323C<seek()> and C<tell()> operate on byte counts, as do C<sysread()>
324and C<sysseek()>.
325
326Notice that because of the default behaviour "input is not UTF-8"
327it is easy to mistakenly write code that keeps on expanding a file
328by repeatedly encoding it in UTF-8:
329
330 # BAD CODE WARNING
331 open F, "file";
332 local $/; # read in the whole file
333 $t = <F>;
334 close F;
335 open F, ">:utf8", "file";
336 print F $t;
337 close F;
338
339If you run this code twice, the contents of the F<file> will be twice
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340UTF-8 encoded. A C<use open ':utf8'> would have avoided the bug, or
341explicitly opening also the F<file> for input as UTF-8.
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342
343=head2 Special Cases
344
345=over 4
346
347=item *
348
349Bit Complement Operator ~ And vec()
350
351The bit complement operator C<~> will produce surprising results if
352used on strings containing Unicode characters. The results are
353consistent with the internal UTF-8 encoding of the characters, but not
354with much else. So don't do that. Similarly for vec(): you will be
355operating on the UTF-8 bit patterns of the Unicode characters, not on
356the bytes, which is very probably not what you want.
357
358=item *
359
360Peeking At UTF-8
361
362One way of peeking inside the internal encoding of Unicode characters
363is to use C<unpack("C*", ...> to get the bytes, or C<unpack("H*", ...)>
364to display the bytes:
365
366 # this will print c4 80 for the UTF-8 bytes 0xc4 0x80
367 print join(" ", unpack("H*", pack("U", 0x100))), "\n";
368
369Yet another way would be to use the Devel::Peek module:
370
371 perl -MDevel::Peek -e 'Dump(chr(0x100))'
372
373That will show the UTF8 flag in FLAGS and both the UTF-8 bytes
374and Unicode characters in PV. See also later in this document
375the discussion about the C<is_utf8> function of the C<Encode> module.
376
377=back
378
379=head2 Advanced Topics
380
381=over 4
382
383=item *
384
385String Equivalence
386
387The question of string equivalence turns somewhat complicated
388in Unicode: what do you mean by equal?
389
390 Is C<LATIN CAPITAL LETTER A WITH ACUTE> equal to
391 C<LATIN CAPITAL LETTER A>?
392
393The short answer is that by default Perl compares equivalence
394(C<eq>, C<ne>) based only on code points of the characters.
395In the above case, no (because 0x00C1 != 0x0041). But sometimes any
396CAPITAL LETTER As being considered equal, or even any As of any case,
397would be desirable.
398
399The long answer is that you need to consider character normalization
400and casing issues: see L<Unicode::Normalize>, and Unicode Technical
401Reports #15 and #21, I<Unicode Normalization Forms> and I<Case
402Mappings>, http://www.unicode.org/unicode/reports/tr15/
403http://www.unicode.org/unicode/reports/tr21/
404
405As of Perl 5.8.0, the's regular expression case-ignoring matching
406implements only 1:1 semantics: one character matches one character.
407In I<Case Mappings> both 1:N and N:1 matches are defined.
408
409=item *
410
411String Collation
412
413People like to see their strings nicely sorted, or as Unicode
414parlance goes, collated. But again, what do you mean by collate?
415
416 Does C<LATIN CAPITAL LETTER A WITH ACUTE> come before or after
417 C<LATIN CAPITAL LETTER A WITH GRAVE>?
418
419The short answer is that by default Perl compares strings (C<lt>,
420C<le>, C<cmp>, C<ge>, C<gt>) based only on the code points of the
421characters. In the above case, after, since 0x00C1 > 0x00C0.
422
423The long answer is that "it depends", and a good answer cannot be
424given without knowing (at the very least) the language context.
425See L<Unicode::Collate>, and I<Unicode Collation Algorithm>
426http://www.unicode.org/unicode/reports/tr10/
427
428=back
429
430=head2 Miscellaneous
431
432=over 4
433
434=item *
435
436Character Ranges
437
438Character ranges in regular expression character classes (C</[a-z]/>)
439and in the C<tr///> (also known as C<y///>) operator are not magically
440Unicode-aware. What this means that C<[a-z]> will not magically start
441to mean "all alphabetic letters" (not that it does mean that even for
4428-bit characters, you should be using C</[[:alpha]]/> for that).
443
444For specifying things like that in regular expressions you can use the
445various Unicode properties, C<\pL> in this particular case. You can
446use Unicode code points as the end points of character ranges, but
447that means that particular code point range, nothing more. For
448further information, see L<perlunicode>.
449
450=item *
451
452String-To-Number Conversions
453
454Unicode does define several other decimal (and numeric) characters
455than just the familiar 0 to 9, such as the Arabic and Indic digits.
456Perl does not support string-to-number conversion for digits other
457than the 0 to 9 (and a to f for hexadecimal).
458
459=back
460
461=head2 Questions With Answers
462
463=over 4
464
465=item Will My Old Scripts Break?
466
467Very probably not. Unless you are generating Unicode characters
468somehow, any old behaviour should be preserved. About the only
469behaviour that has changed and which could start generating Unicode
470is the old behaviour of C<chr()> where supplying an argument more
471than 255 produced a character modulo 255 (for example, C<chr(300)>
472was equal to C<chr(45)>).
473
474=item How Do I Make My Scripts Work With Unicode?
475
476Very little work should be needed since nothing changes until you
477somehow generate Unicode data. The greatest trick will be getting
478input as Unicode, and for that see the earlier I/O discussion.
479
480=item How Do I Know Whether My String Is In Unicode?
481
482You shouldn't care. No, you really shouldn't. If you have
483to care (beyond the cases described above), it means that we
484didn't get the transparency of Unicode quite right.
485
486Okay, if you insist:
487
488 use Encode 'is_utf8';
489 print is_utf8($string) ? 1 : 0, "\n";
490
491But note that this doesn't mean that any of the characters in the
492string are necessary UTF-8 encoded, or that any of the characters have
493code points greater than 0xFF (255) or even 0x80 (128), or that the
494string has any characters at all. All the C<is_utf8()> does is to
495return the value of the internal "utf8ness" flag attached to the
496$string. If the flag is on, characters added to that string will be
497automatically upgraded to UTF-8 (and even then only if they really
498need to be upgraded, that is, if their code point is greater than 0xFF).
499
500Sometimes you might really need to know the byte length of a string
501instead of the character length. For that use the C<bytes> pragma
502and its only defined function C<length()>:
503
504 my $unicode = chr(0x100);
505 print length($unicode), "\n"; # will print 1
506 use bytes;
507 print length($unicode), "\n"; # will print 2 (the 0xC4 0x80 of the UTF-8)
508
509=item How Do I Detect Invalid UTF-8?
510
511Either
512
513 use Encode 'encode_utf8';
514 if (encode_utf8($string)) {
515 # valid
516 } else {
517 # invalid
518 }
519
520or
521
522 use warnings;
523 @chars = unpack("U0U*", "\xFF"); # will warn
524
525The warning will be C<Malformed UTF-8 character (byte 0xff) in
526unpack>. The "U0" means "expect strictly UTF-8 encoded Unicode".
527Without that the C<unpack("U*", ...)> would accept also data like
528C<chr(0xFF>).
529
530=item How Do I Convert Data Into UTF-8? Or Vice Versa?
531
532This probably isn't as useful (or simple) as you might think.
533Also, normally you shouldn't need to.
534
535In one sense what you are asking doesn't make much sense: UTF-8 is
536(intended as an) Unicode encoding, so converting "data" into UTF-8
537isn't meaningful unless you know in what character set and encoding
538the binary data is in, and in this case you can use C<Encode>.
539
540 use Encode 'from_to';
541 from_to($data, "iso-8859-1", "utf-8"); # from latin-1 to utf-8
542
543If you have ASCII (really 7-bit US-ASCII), you already have valid
544UTF-8, the lowest 128 characters of UTF-8 encoded Unicode and US-ASCII
545are equivalent.
546
547If you have Latin-1 (or want Latin-1), you can just use pack/unpack:
548
549 $latin1 = pack("C*", unpack("U*", $utf8));
550 $utf8 = pack("U*", unpack("C*", $latin1));
551
552(The same works for EBCDIC.)
553
554If you have a sequence of bytes you B<know> is valid UTF-8,
555but Perl doesn't know it yet, you can make Perl a believer, too:
556
557 use Encode 'decode_utf8';
558 $utf8 = decode_utf8($bytes);
559
560You can convert well-formed UTF-8 to a sequence of bytes, but if
561you just want to convert random binary data into UTF-8, you can't.
562Any random collection of bytes isn't well-formed UTF-8. You can
563use C<unpack("C*", $string)> for the former, and you can create
564well-formed Unicode/UTF-8 data by C<pack("U*", 0xff, ...)>.
565
566=item How Do I Display Unicode? How Do I Input Unicode?
567
568See http://www.hclrss.demon.co.uk/unicode/ and
569http://www.cl.cam.ac.uk/~mgk25/unicode.html
570
571=item How Does Unicode Work With Traditional Locales?
572
573In Perl, not very well. Avoid using locales through the C<locale>
574pragma. Use only one or the other.
575
576=back
577
578=head2 Hexadecimal Notation
579
580The Unicode standard prefers using hexadecimal notation because that
581shows better the division of Unicode into blocks of 256 characters.
582Hexadecimal is also simply shorter than decimal. You can use decimal
583notation, too, but learning to use hexadecimal just makes life easier
584with the Unicode standard.
585
586The C<0x> prefix means a hexadecimal number, the digits are 0-9 I<and>
587a-f (or A-F, case doesn't matter). Each hexadecimal digit represents
588four bits, or half a byte. C<print 0x..., "\n"> will show a
589hexadecimal number in decimal, and C<printf "%x\n", $decimal> will
590show a decimal number in hexadecimal. If you have just the
591"hexdigits" of a hexadecimal number, you can use the C<hex()>
592function.
593
594 print 0x0009, "\n"; # 9
595 print 0x000a, "\n"; # 10
596 print 0x000f, "\n"; # 15
597 print 0x0010, "\n"; # 16
598 print 0x0011, "\n"; # 17
599 print 0x0100, "\n"; # 256
600
601 print 0x0041, "\n"; # 65
602
603 printf "%x\n", 65; # 41
604 printf "%#x\n", 65; # 0x41
605
606 print hex("41"), "\n"; # 65
607
608=head2 Further Resources
609
610=over 4
611
612=item *
613
614Unicode Consortium
615
616 http://www.unicode.org/
617
618=item *
619
620Unicode FAQ
621
622 http://www.unicode.org/unicode/faq/
623
624=item *
625
626Unicode Glossary
627
628 http://www.unicode.org/glossary/
629
630=item *
631
632Unicode Useful Resources
633
634 http://www.unicode.org/unicode/onlinedat/resources.html
635
636=item *
637
638Unicode and Multilingual Support in HTML, Fonts, Web Browsers and Other Applications
639
640 http://www.hclrss.demon.co.uk/unicode/
641
642=item *
643
644UTF-8 and Unicode FAQ for Unix/Linux
645
646 http://www.cl.cam.ac.uk/~mgk25/unicode.html
647
648=item *
649
650Legacy Character Sets
651
652 http://www.czyborra.com/
653 http://www.eki.ee/letter/
654
655=item *
656
657The Unicode support files live within the Perl installation in the
658directory
659
660 $Config{installprivlib}/unicore
661
662in Perl 5.8.0 or newer, and
663
664 $Config{installprivlib}/unicode
665
666in the Perl 5.6 series. (The renaming to F<lib/unicore> was done to
667avoid naming conflicts with lib/Unicode in case-insensitive filesystems.)
668The main Unicode data file is F<Unicode.txt> (or F<Unicode.301> in
669Perl 5.6.1.) You can find the C<$Config{installprivlib}> by
670
671 perl "-V:installprivlib"
672
673Note that some of the files have been renamed from the Unicode
674standard since the Perl installation tries to live by the "8.3"
675filenaming restrictions. The renamings are shown in the
676accompanying F<rename> file.
677
678You can explore various information from the Unicode data files using
679the C<Unicode::UCD> module.
680
681=back
682
683=head1 SEE ALSO
684
685L<perlunicode>, L<Encode>, L<encoding>, L<open>, L<utf8>, L<bytes>,
686L<perlretut>, L<Unicode::Collate>, L<Unicode::Normalize>, L<Unicode::UCD>
687
688=head1 ACKNOWLEDGEMENTS
689
690Thanks to the kind readers of the perl5-porters@perl.org,
691perl-unicode@perl.org, linux-utf8@nl.linux.org, and unicore@unicode.org
692mailing lists for their valuable feedback.
693
694=head1 AUTHOR, COPYRIGHT, AND LICENSE
695
696Copyright 2001 Jarkko Hietaniemi <jhi@iki.fi>
697
698This document may be distributed under the same terms as Perl itself.