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1 | =head1 NAME |
2 | |
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3 | Encode::Supported -- Encodings supported by Encode |
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4 | |
5 | =head1 DESCRIPTION |
6 | |
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7 | =head2 Encoding Names |
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8 | |
9 | Encoding names are case insensitive. White space in names |
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10 | is ignored. In addition, an encoding may have aliases. |
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11 | Each encoding has one "canonical" name. The "canonical" |
12 | name is chosen from the names of the encoding by picking |
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13 | the first in the following sequence (with a few exceptions). |
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14 | |
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15 | =over 4 |
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16 | |
17 | =item * |
18 | |
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19 | The name used by the Perl community. That includes 'utf8' and 'ascii'. |
20 | Unlike aliases, canonical names directly reach the method so such |
21 | frequently used words like 'utf8' don't need to do alias lookups. |
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22 | |
23 | =item * |
24 | |
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25 | The MIME name as defined in IETF RFCs. This includes all "iso-"s. |
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26 | |
27 | =item * |
28 | |
29 | The name in the IANA registry. |
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30 | |
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31 | =item * |
32 | |
33 | The name used by the organization that defined it. |
34 | |
35 | =back |
36 | |
37 | In case I<de jure> canonical names differ from that of the Encode |
38 | module, they are always aliased if it ever be implemented. So you can |
39 | safely tell if a given encoding is implemented or not just by passing |
40 | the canonical name. |
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41 | |
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42 | Because of all the alias issues, and because in the general case |
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43 | encodings have state, "Encode" uses an encoding object internally |
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44 | once an operation is in progress. |
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45 | |
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46 | =head1 Supported Encodings |
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47 | |
48 | As of Perl 5.8.0, at least the following encodings are recognized. |
49 | Note that unless otherwise specified, they are all case insensitive |
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50 | (via alias) and all occurrence of spaces are replaced with '-'. |
51 | In other words, "ISO 8859 1" and "iso-8859-1" are identical. |
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52 | |
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53 | Encodings are categorized and implemented in several different modules |
54 | but you don't have to C<use Encode::XX> to make them available for |
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55 | most cases. Encode.pm will automatically load those modules on demand. |
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56 | |
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57 | =head2 Built-in Encodings |
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58 | |
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59 | The following encodings are always available. |
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60 | |
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61 | Canonical Aliases Comments & References |
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62 | ---------------------------------------------------------------- |
2d06ad02 |
63 | ascii US-ascii ISO-646-US [ECMA] |
f0a41339 |
64 | ascii-ctrl Special Encoding |
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65 | iso-8859-1 latin1 [ISO] |
f0a41339 |
66 | null Special Encoding |
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67 | utf8 UTF-8 [RFC2279] |
c731e18e |
68 | ---------------------------------------------------------------- |
69 | |
f0a41339 |
70 | I<null> and I<ascii-ctrl> are special. "null" fails for all character |
71 | so when you set fallback mode to PERLQQ, HTMLCREF or XMLCREF, ALL |
72 | CHARACTERS will fall back to character references. Ditto for |
73 | "ascii-ctrl" except for control characters. For fallback modes, see |
74 | L<Encode>. |
75 | |
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76 | =head2 Encode::Unicode -- other Unicode encodings |
77 | |
78 | Unicode coding schemes other than native utf8 are supported by |
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79 | Encode::Unicode, which will be autoloaded on demand. |
c731e18e |
80 | |
81 | ---------------------------------------------------------------- |
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82 | UCS-2BE UCS-2, iso-10646-1 [IANA, UC] |
83 | UCS-2LE [UC] |
84 | UTF-16 [UC] |
85 | UTF-16BE [UC] |
86 | UTF-16LE [UC] |
87 | UTF-32 [UC] |
126bf8bf |
88 | UTF-32BE UCS-4 [UC] |
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89 | UTF-32LE [UC] |
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90 | UTF-7 [RFC2152] |
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91 | ---------------------------------------------------------------- |
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92 | |
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93 | To find how (UCS-2|UTF-(16|32))(LE|BE)? differ from one another, |
f2a2953c |
94 | see L<Encode::Unicode>. |
95 | |
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96 | UTF-7 is a special encoding which "re-encodes" UTF-16BE into a 7-bit |
c2878c71 |
97 | encoding. It is implemented seperately by Encode::Unicode::UTF7. |
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98 | |
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99 | =head2 Encode::Byte -- Extended ASCII |
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100 | |
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101 | Encode::Byte implements most single-byte encodings except for |
102 | Symbols and EBCDIC. The following encodings are based on single-byte |
103 | encodings implemented as extended ASCII. Most of them map |
104 | \x80-\xff (upper half) to non-ASCII characters. |
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105 | |
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106 | =over 4 |
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107 | |
108 | =item ISO-8859 and corresponding vendor mappings |
109 | |
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110 | Since there are so many, they are presented in table format with |
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111 | languages and corresponding encoding names by vendors. Note that |
112 | the table is sorted in order of ISO-8859 and the corresponding vendor |
113 | mappings are slightly different from that of ISO. See |
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114 | L<http://czyborra.com/charsets/iso8859.html> for details. |
115 | |
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116 | Lang/Regions ISO/Other Std. DOS Windows Macintosh Others |
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117 | ---------------------------------------------------------------- |
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118 | N. America (ASCII) cp437 AdobeStandardEncoding |
119 | cp863 (DOSCanadaF) |
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120 | W. Europe iso-8859-1 cp850 cp1252 MacRoman nextstep |
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121 | hp-roman8 |
122 | cp860 (DOSPortuguese) |
123 | Cntrl. Europe iso-8859-2 cp852 cp1250 MacCentralEurRoman |
124 | MacCroatian |
125 | MacRomanian |
126 | MacRumanian |
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127 | Latin3[1] iso-8859-3 |
128 | Latin4[2] iso-8859-4 |
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129 | Cyrillics iso-8859-5 cp855 cp1251 MacCyrillic |
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130 | (See also next section) cp866 MacUkrainian |
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131 | Arabic iso-8859-6 cp864 cp1256 MacArabic |
132 | cp1006 MacFarsi |
133 | Greek iso-8859-7 cp737 cp1253 MacGreek |
134 | cp869 (DOSGreek2) |
135 | Hebrew iso-8859-8 cp862 cp1255 MacHebrew |
136 | Turkish iso-8859-9 cp857 cp1254 MacTurkish |
137 | Nordics iso-8859-10 cp865 |
138 | cp861 MacIcelandic |
139 | MacSami |
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140 | Thai iso-8859-11[3] cp874 MacThai |
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141 | (iso-8859-12 is nonexistent. Reserved for Indics?) |
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142 | Baltics iso-8859-13 cp775 cp1257 |
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143 | Celtics iso-8859-14 |
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144 | Latin9 [4] iso-8859-15 |
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145 | Latin10 iso-8859-16 |
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146 | Vietnamese viscii cp1258 MacVietnamese |
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147 | ---------------------------------------------------------------- |
148 | |
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149 | [1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9. |
150 | [2] Baltics. Now on 8859-10, except for Latvian. |
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151 | [3] TIS 620 + Non-Breaking Space (0xA0 / U+00A0) |
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152 | [4] Nicknamed Latin0; the Euro sign as well as French and Finnish |
153 | letters that are missing from 8859-1 were added. |
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154 | |
155 | All cp* are also available as ibm-*, ms-*, and windows-* . See also |
156 | L<http://czyborra.com/charsets/codepages.html>. |
157 | |
158 | Macintosh encodings don't seem to be registered in such entities as |
159 | IANA. "Canonical" names in Encode are based upon Apple's Tech Note |
160 | 1150. See L<http://developer.apple.com/technotes/tn/tn1150.html> |
0ab8f81e |
161 | for details. |
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162 | |
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163 | =item KOI8 - De Facto Standard for the Cyrillic world |
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164 | |
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165 | Though ISO-8859 does have ISO-8859-5, the KOI8 series is far more |
166 | popular in the Net. L<Encode> comes with the following KOI charsets. |
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167 | For gory details, see L<http://czyborra.com/charsets/cyrillic.html> |
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168 | |
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169 | ---------------------------------------------------------------- |
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170 | koi8-f |
171 | koi8-r cp878 [RFC1489] |
172 | koi8-u [RFC2319] |
85982a32 |
173 | ---------------------------------------------------------------- |
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174 | |
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175 | =item gsm0338 - Hentai Latin 1 |
176 | |
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177 | GSM0338 is for GSM handsets. Though it shares alphanumerals with |
178 | ASCII, control character ranges and other parts are mapped very |
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179 | differently, mainly to store Greek characters. There are also escape |
180 | sequences (starting with 0x1B) to cover e.g. the Euro sign. Some |
181 | special cases like a trailing 0x00 byte or a lone 0x1B byte are not |
182 | well-defined and decode() will return an empty string for them. |
183 | One possible workaround is |
184 | |
185 | $gsm =~ s/\x00\z/\x00\x00/; |
186 | $uni = decode("gsm0338", $gsm); |
187 | $uni .= "\xA0" if $gsm =~ /\x1B\z/; |
188 | |
189 | Note that the Encode implementation of GSM0338 does not implement the |
190 | reuse of Latin capital letters as Greek capital letters (for example, |
191 | the 0x5A is U+005A (LATIN CAPITAL LETTER Z), not U+0396 (GREEK CAPITAL |
192 | LETTER ZETA). |
193 | |
194 | The GSM0338 is also covered in Encode::Byte even though it is not |
195 | an "extended ASCII" encoding. |
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196 | |
197 | =back |
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198 | |
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199 | =head2 CJK: Chinese, Japanese, Korean (Multibyte) |
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200 | |
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201 | Note that Vietnamese is listed above. Also read "Encoding vs Charset" |
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202 | below. Also note that these are implemented in distinct modules by |
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203 | countries, due to the size concerns (simplified Chinese is mapped |
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204 | to 'CN', continental China, while traditional Chinese is mapped to |
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205 | 'TW', Taiwan). Please refer to their respective documentation pages. |
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206 | |
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207 | =over 4 |
208 | |
209 | =item Encode::CN -- Continental China |
210 | |
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211 | Standard DOS/Win Macintosh Comment/Reference |
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212 | ---------------------------------------------------------------- |
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213 | euc-cn [1] MacChineseSimp |
214 | (gbk) cp936 [2] |
215 | gb12345-raw { GB12345 without CES } |
216 | gb2312-raw { GB2312 without CES } |
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217 | hz |
218 | iso-ir-165 |
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219 | ---------------------------------------------------------------- |
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220 | |
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221 | [1] GB2312 is aliased to this. See L<Microsoft-related naming mess> |
222 | [2] gbk is aliased to this. See L<Microsoft-related naming mess> |
f2a2953c |
223 | |
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224 | =item Encode::JP -- Japan |
225 | |
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226 | Standard DOS/Win Macintosh Comment/Reference |
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227 | ---------------------------------------------------------------- |
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228 | euc-jp |
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229 | shiftjis cp932 macJapanese |
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230 | 7bit-jis |
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231 | iso-2022-jp [RFC1468] |
232 | iso-2022-jp-1 [RFC2237] |
f2a2953c |
233 | jis0201-raw { JIS X 0201 (roman + halfwidth kana) without CES } |
234 | jis0208-raw { JIS X 0208 (Kanji + fullwidth kana) without CES } |
235 | jis0212-raw { JIS X 0212 (Extended Kanji) without CES } |
67d7b5ef |
236 | ---------------------------------------------------------------- |
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237 | |
238 | =item Encode::KR -- Korea |
239 | |
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240 | Standard DOS/Win Macintosh Comment/Reference |
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241 | ---------------------------------------------------------------- |
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242 | euc-kr MacKorean [RFC1557] |
243 | cp949 [1] |
244 | iso-2022-kr [RFC1557] |
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245 | johab [KS X 1001:1998, Annex 3] |
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246 | ksc5601-raw { KSC5601 without CES } |
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247 | ---------------------------------------------------------------- |
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248 | |
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249 | [1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this. |
250 | See below. |
251 | |
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252 | =item Encode::TW -- Taiwan |
253 | |
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254 | Standard DOS/Win Macintosh Comment/Reference |
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255 | ---------------------------------------------------------------- |
b0b300a3 |
256 | big5-eten cp950 MacChineseTrad {big5 aliased to big5-eten} |
257 | big5-hkscs |
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258 | ---------------------------------------------------------------- |
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259 | |
260 | =item Encode::HanExtra -- More Chinese via CPAN |
261 | |
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262 | Due to the size concerns, additional Chinese encodings below are |
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263 | distributed separately on CPAN, under the name Encode::HanExtra. |
264 | |
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265 | Standard DOS/Win Macintosh Comment/Reference |
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266 | ---------------------------------------------------------------- |
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267 | big5ext CMEX's Big5e Extension |
268 | big5plus CMEX's Big5+ Extension |
269 | cccii Chinese Character Code for Information Interchange |
270 | euc-tw EUC (Extended Unix Character) |
271 | gb18030 GBK with Traditional Characters |
272 | ---------------------------------------------------------------- |
273 | |
274 | =item Encode::JIS2K -- JIS X 0213 encodings via CPAN |
275 | |
276 | Due to size concerns, additional Japanese encodings below are |
277 | distributed separately on CPAN, under the name Encode::JIS2K. |
278 | |
279 | Standard DOS/Win Macintosh Comment/Reference |
280 | ---------------------------------------------------------------- |
281 | euc-jisx0213 |
282 | shiftjisx0123 |
283 | iso-2022-jp-3 |
284 | jis0213-1-raw |
285 | jis0213-2-raw |
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286 | ---------------------------------------------------------------- |
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287 | |
288 | =back |
289 | |
290 | =head2 Miscellaneous encodings |
291 | |
292 | =over 4 |
293 | |
294 | =item Encode::EBCDIC |
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295 | |
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296 | See L<perlebcdic> for details. |
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297 | |
67d7b5ef |
298 | ---------------------------------------------------------------- |
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299 | cp37 |
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300 | cp500 |
301 | cp875 |
302 | cp1026 |
303 | cp1047 |
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304 | posix-bc |
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305 | ---------------------------------------------------------------- |
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306 | |
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307 | =item Encode::Symbols |
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308 | |
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309 | For symbols and dingbats. |
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310 | |
67d7b5ef |
311 | ---------------------------------------------------------------- |
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312 | symbol |
313 | dingbats |
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314 | MacDingbats |
315 | AdobeZdingbat |
316 | AdobeSymbol |
67d7b5ef |
317 | ---------------------------------------------------------------- |
318 | |
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319 | =item Encode::MIME::Header |
320 | |
321 | Strictly speaking, MIME header encoding documented in RFC 2047 is more |
ab3374e4 |
322 | of encapsulation than encoding. However, their support in modern |
323 | world is imperative so they are supported. |
e8c86ba6 |
324 | |
325 | ---------------------------------------------------------------- |
326 | MIME-Header [RFC2047] |
327 | MIME-B [RFC2047] |
328 | MIME-Q [RFC2047] |
329 | ---------------------------------------------------------------- |
330 | |
331 | =item Encode::Guess |
332 | |
333 | This one is not a name of encoding but a utility that lets you pick up |
334 | the most appropriate encoding for a data out of given I<suspects>. See |
335 | L<Encode::Guess> for details. |
336 | |
67d7b5ef |
337 | =back |
338 | |
339 | =head1 Unsupported encodings |
340 | |
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341 | The following encodings are not supported as yet; some because they |
342 | are rarely used, some because of technical difficulties. They may |
343 | be supported by external modules via CPAN in the future, however. |
67d7b5ef |
344 | |
345 | =over 4 |
346 | |
347 | =item ISO-2022-JP-2 [RFC1554] |
348 | |
349 | Not very popular yet. Needs Unicode Database or equivalent to |
0ab8f81e |
350 | implement encode() (because it includes JIS X 0208/0212, KSC5601, and |
351 | GB2312 simultaneously, whose code points in Unicode overlap. So you |
352 | need to lookup the database to determine to what character set a given |
67d7b5ef |
353 | Unicode character should belong). |
354 | |
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355 | =item ISO-2022-CN [RFC1922] |
67d7b5ef |
356 | |
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357 | Not very popular. Needs CNS 11643-1 and -2 which are not available in |
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358 | this module. CNS 11643 is supported (via euc-tw) in Encode::HanExtra. |
0ab8f81e |
359 | Autrijus Tang may add support for this encoding in his module in future. |
67d7b5ef |
360 | |
0ab8f81e |
361 | =item Various HP-UX encodings |
67d7b5ef |
362 | |
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363 | The following are unsupported due to the lack of mapping data. |
364 | |
67d7b5ef |
365 | '8' - arabic8, greek8, hebrew8, kana8, thai8, and turkish8 |
962111ca |
366 | '15' - japanese15, korean15, and roi15 |
67d7b5ef |
367 | |
368 | =item Cyrillic encoding ISO-IR-111 |
369 | |
0ab8f81e |
370 | Anton Tagunov doubts its usefulness. |
67d7b5ef |
371 | |
372 | =item ISO-8859-8-1 [Hebrew] |
373 | |
a999c27c |
374 | None of the Encode team knows Hebrew enough (ISO-8859-8, cp1255 and |
375 | MacHebrew are supported because and just because there were mappings |
962111ca |
376 | available at L<http://www.unicode.org/>). Contributions welcome. |
377 | |
378 | =item ISIRI 3342, Iran System, ISIRI 2900 [Farsi] |
379 | |
380 | Ditto. |
67d7b5ef |
381 | |
382 | =item Thai encoding TCVN |
383 | |
384 | Ditto. |
385 | |
386 | =item Vietnamese encodings VPS |
387 | |
0ab8f81e |
388 | Though Jungshik Shin has reported that Mozilla supports this encoding, |
389 | it was too late before 5.8.0 for us to add it. In the future, it |
390 | may be available via a separate module. See |
962111ca |
391 | L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.uf> |
392 | and |
a999c27c |
393 | L<http://lxr.mozilla.org/seamonkey/source/intl/uconv/ucvlatin/vps.ut> |
394 | if you are interested in helping us. |
67d7b5ef |
395 | |
962111ca |
396 | =item Various Mac encodings |
67d7b5ef |
397 | |
962111ca |
398 | The following are unsupported due to the lack of mapping data. |
a999c27c |
399 | |
400 | MacArmenian, MacBengali, MacBurmese, MacEthiopic |
401 | MacExtArabic, MacGeorgian, MacKannada, MacKhmer |
402 | MacLaotian, MacMalayalam, MacMongolian, MacOriya |
403 | MacSinhalese, MacTamil, MacTelugu, MacTibetan |
404 | MacVietnamese |
405 | |
0ab8f81e |
406 | The rest which are already available are based upon the vendor mappings |
962111ca |
407 | at L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/> . |
a999c27c |
408 | |
409 | =item (Mac) Indic encodings |
410 | |
0ab8f81e |
411 | The maps for the following are available at L<http://www.unicode.org/> |
412 | but remain unsupport because those encodings need algorithmical |
413 | approach, currently unsupported by F<enc2xs>: |
67d7b5ef |
414 | |
a999c27c |
415 | MacDevanagari |
416 | MacGurmukhi |
417 | MacGujarati |
67d7b5ef |
418 | |
a999c27c |
419 | For details, please see C<Unicode mapping issues and notes:> at |
420 | L<http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT> . |
421 | |
422 | I believe this issue is prevalent not only for Mac Indics but also in |
962111ca |
423 | other Indic encodings, but the above were the only Indic encodings |
a999c27c |
424 | maps that I could find at L<http://www.unicode.org/> . |
5129552c |
425 | |
426 | =back |
5d030b67 |
427 | |
a999c27c |
428 | =head1 Encoding vs. Charset -- terminology |
5d030b67 |
429 | |
0ab8f81e |
430 | We are used to using the term (character) I<encoding> and I<character |
431 | set> interchangeably. But just as confusing the terms byte and |
432 | character is dangerous and the terms should be differentiated when |
433 | needed, we need to differentiate I<encoding> and I<character set>. |
5d030b67 |
434 | |
0ab8f81e |
435 | To understand that, here is a description of how we make computers |
436 | grok our characters. |
a999c27c |
437 | |
438 | =over 4 |
439 | |
440 | =item * |
67d7b5ef |
441 | |
a999c27c |
442 | First we start with which characters to include. We call this |
443 | collection of characters I<character repertoire>. |
5d030b67 |
444 | |
a999c27c |
445 | =item * |
5d030b67 |
446 | |
a999c27c |
447 | Then we have to give each character a unique ID so your computer can |
0ab8f81e |
448 | tell the difference between 'a' and 'A'. This itemized character |
962111ca |
449 | repertoire is now a I<character set>. |
a63c962f |
450 | |
a999c27c |
451 | =item * |
452 | |
453 | If your computer can grow the character set without further |
0ab8f81e |
454 | processing, you can go ahead and use it. This is called a I<coded |
a999c27c |
455 | character set> (CCS) or I<raw character encoding>. ASCII is used this |
456 | way for most cases. |
457 | |
458 | =item * |
459 | |
0ab8f81e |
460 | But in many cases, especially multi-byte CJK encodings, you have to |
a999c27c |
461 | tweak a little more. Your network connection may not accept any data |
0ab8f81e |
462 | with the Most Significant Bit set, and your computer may not be able to |
a999c27c |
463 | tell if a given byte is a whole character or just half of it. So you |
464 | have to I<encode> the character set to use it. |
465 | |
466 | A I<character encoding scheme> (CES) determines how to encode a given |
467 | character set, or a set of multiple character sets. 7bit ISO-2022 is |
0ab8f81e |
468 | an example of a CES. You switch between character sets via I<escape |
469 | sequences>. |
67d7b5ef |
470 | |
471 | =back |
472 | |
0ab8f81e |
473 | Technically, or mathematically, speaking, a character set encoded in |
a999c27c |
474 | such a CES that maps character by character may form a CCS. EUC is such |
0ab8f81e |
475 | an example. The CES of EUC is as follows: |
67d7b5ef |
476 | |
a999c27c |
477 | =over 4 |
5d030b67 |
478 | |
a999c27c |
479 | =item * |
5d030b67 |
480 | |
a999c27c |
481 | Map ASCII unchanged. |
482 | |
483 | =item * |
484 | |
485 | Map such a character set that consists of 94 or 96 powered by N |
486 | members by adding 0x80 to each byte. |
487 | |
488 | =item * |
489 | |
0ab8f81e |
490 | You can also use 0x8e and 0x8f to indicate that the following sequence of |
491 | characters belongs to yet another character set. To each following byte |
492 | is added the value 0x80. |
a999c27c |
493 | |
494 | =back |
495 | |
0ab8f81e |
496 | By carefully looking at the encoded byte sequence, you can find that the |
497 | byte sequence conforms a unique number. In that sense, EUC is a CCS |
a999c27c |
498 | generated by a CES above from up to four CCS (complicated?). UTF-8 |
0ab8f81e |
499 | falls into this category. See L<perlUnicode/"UTF-8"> to find out how |
a999c27c |
500 | UTF-8 maps Unicode to a byte sequence. |
501 | |
0ab8f81e |
502 | You may also have found out by now why 7bit ISO-2022 cannot comprise |
503 | a CCS. If you look at a byte sequence \x21\x21, you can't tell if |
504 | it is two !'s or IDEOGRAPHIC SPACE. EUC maps the latter to \xA1\xA1 |
505 | so you have no trouble differentiating between "!!". and S<" ">. |
67d7b5ef |
506 | |
a63c962f |
507 | =head1 Encoding Classification (by Anton Tagunov and Dan Kogai) |
508 | |
509 | This section tries to classify the supported encodings by their |
510 | applicability for information exchange over the Internet and to |
511 | choose the most suitable aliases to name them in the context of |
512 | such communication. |
513 | |
0ab8f81e |
514 | =over 4 |
67d7b5ef |
515 | |
516 | =item * |
517 | |
0ab8f81e |
518 | To (en|de)code encodings marked by C<(**)>, you need |
a999c27c |
519 | C<Encode::HanExtra>, available from CPAN. |
67d7b5ef |
520 | |
521 | =back |
522 | |
a63c962f |
523 | Encoding names |
5d030b67 |
524 | |
f2a2953c |
525 | US-ASCII UTF-8 ISO-8859-* KOI8-R |
526 | Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1 |
527 | EUC-KR Big5 GB2312 |
a999c27c |
528 | |
0ab8f81e |
529 | are registered with IANA as preferred MIME names and may |
a999c27c |
530 | be used over the Internet. |
5d030b67 |
531 | |
c731e18e |
532 | C<Shift_JIS> has been officialized by JIS X 0208:1997. |
a999c27c |
533 | L<Microsoft-related naming mess> gives details. |
5d030b67 |
534 | |
a999c27c |
535 | C<GB2312> is the IANA name for C<EUC-CN>. |
536 | See L<Microsoft-related naming mess> for details. |
537 | |
538 | C<GB_2312-80> I<raw> encoding is available as C<gb2312-raw> |
f2a2953c |
539 | with Encode. See L<Encode::CN> for details. |
5d030b67 |
540 | |
a63c962f |
541 | EUC-CN |
f2a2953c |
542 | KOI8-U [RFC2319] |
5d030b67 |
543 | |
a999c27c |
544 | have not been registered with IANA (as of March 2002) but |
545 | seem to be supported by major web browsers. |
0ab8f81e |
546 | The IANA name for C<EUC-CN> is C<GB2312>. |
67d7b5ef |
547 | |
548 | KS_C_5601-1987 |
549 | |
a999c27c |
550 | is heavily misused. |
551 | See L<Microsoft-related naming mess> for details. |
552 | |
553 | C<KS_C_5601-1987> I<raw> encoding is available as C<kcs5601-raw> |
f2a2953c |
554 | with Encode. See L<Encode::KR> for details. |
555 | |
556 | UTF-16 UTF-16BE UTF-16LE |
557 | |
448e90bb |
558 | are IANA-registered C<charset>s. See [RFC 2781] for details. |
f2a2953c |
559 | Jungshik Shin reports that UTF-16 with a BOM is well accepted |
560 | by MS IE 5/6 and NS 4/6. Beware however that |
561 | |
0ab8f81e |
562 | =over 4 |
f2a2953c |
563 | |
564 | =item * |
5d030b67 |
565 | |
f2a2953c |
566 | C<UTF-16> support in any software you're going to be |
567 | using/interoperating with has probably been less tested |
568 | then C<UTF-8> support |
5d030b67 |
569 | |
f2a2953c |
570 | =item * |
571 | |
c731e18e |
572 | C<UTF-8> coded data seamlessly passes traditional |
573 | command piping (C<cat>, C<more>, etc.) while C<UTF-16> coded |
0ab8f81e |
574 | data is likely to cause confusion (with its zero bytes, |
f2a2953c |
575 | for example) |
576 | |
577 | =item * |
578 | |
579 | it is beyond the power of words to describe the way HTML browsers |
0ab8f81e |
580 | encode non-C<ASCII> form data. To get a general impression, visit |
f2a2953c |
581 | L<http://ppewww.ph.gla.ac.uk/~flavell/charset/form-i18n.html>. |
0ab8f81e |
582 | While encoding of form data has stabilized for C<UTF-8> encoded pages |
583 | (at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to |
584 | expect fun (and cross-browser discrepancies) with C<UTF-16> encoded |
f2a2953c |
585 | pages! |
586 | |
587 | =back |
588 | |
589 | The rule of thumb is to use C<UTF-8> unless you know what |
c731e18e |
590 | you're doing and unless you really benefit from using C<UTF-16>. |
a999c27c |
591 | |
f2a2953c |
592 | ISO-IR-165 [RFC1345] |
5d030b67 |
593 | VISCII |
a63c962f |
594 | GB 12345 |
f2a2953c |
595 | GB 18030 (**) (see links bellow) |
596 | EUC-TW (**) |
5d030b67 |
597 | |
598 | are totally valid encodings but not registered at IANA. |
a63c962f |
599 | The names under which they are listed here are probably the |
600 | most widely-known names for these encodings and are recommended |
601 | names. |
602 | |
f2a2953c |
603 | BIG5PLUS (**) |
a63c962f |
604 | |
0ab8f81e |
605 | is a proprietary name. |
5d030b67 |
606 | |
a999c27c |
607 | =head2 Microsoft-related naming mess |
608 | |
609 | Microsoft products misuse the following names: |
5d030b67 |
610 | |
0ab8f81e |
611 | =over 4 |
a63c962f |
612 | |
a999c27c |
613 | =item KS_C_5601-1987 |
5d030b67 |
614 | |
a999c27c |
615 | Microsoft extension to C<EUC-KR>. |
5d030b67 |
616 | |
c731e18e |
617 | Proper names: C<CP949>, C<UHC>, C<x-windows-949> (as used by Mozilla). |
67d7b5ef |
618 | |
f2a2953c |
619 | See L<http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html> |
a999c27c |
620 | for details. |
5d030b67 |
621 | |
f2a2953c |
622 | Encode aliases C<KS_C_5601-1987> to C<cp949> to reflect this common |
623 | misusage. I<Raw> C<KS_C_5601-1987> encoding is available as |
624 | C<kcs5601-raw>. |
5d030b67 |
625 | |
f2a2953c |
626 | See L<Encode::KR> for details. |
67d7b5ef |
627 | |
a999c27c |
628 | =item GB2312 |
67d7b5ef |
629 | |
a999c27c |
630 | Microsoft extension to C<EUC-CN>. |
a63c962f |
631 | |
a999c27c |
632 | Proper names: C<CP936>, C<GBK>. |
a63c962f |
633 | |
a999c27c |
634 | C<GB2312> has been registered in the C<EUC-CN> meaning at |
635 | IANA. This has partially repaired the situation: Microsoft's |
636 | C<GB2312> has become a superset of the official C<GB2312>. |
67d7b5ef |
637 | |
a999c27c |
638 | Encode aliases C<GB2312> to C<euc-cn> in full agreement with |
639 | IANA registration. C<cp936> is supported separately. |
f2a2953c |
640 | I<Raw> C<GB_2312-80> encoding is available as C<gb2312-raw>. |
a999c27c |
641 | |
f2a2953c |
642 | See L<Encode::CN> for details. |
a999c27c |
643 | |
644 | =item Big5 |
645 | |
646 | Microsoft extension to C<Big5>. |
647 | |
648 | Proper name: C<CP950>. |
649 | |
650 | Encode separately supports C<Big5> and C<cp950>. |
651 | |
652 | =item Shift_JIS |
653 | |
654 | Microsoft's understanding of C<Shift_JIS>. |
655 | |
656 | JIS has not endorsed the full Microsoft standard however. |
657 | The official C<Shift_JIS> includes only JIS X 0201 and JIS X 0208 |
0ab8f81e |
658 | character sets, while Microsoft has always used C<Shift_JIS> |
85982a32 |
659 | to encode a wider character repertoire. See C<IANA> registration for |
c731e18e |
660 | C<Windows-31J>. |
a999c27c |
661 | |
0ab8f81e |
662 | As a historical predecessor, Microsoft's variant |
663 | probably has more rights for the name, though it may be objected |
a999c27c |
664 | that Microsoft shouldn't have used JIS as part of the name |
665 | in the first place. |
666 | |
8f1ed24a |
667 | Unambiguous name: C<CP932>. C<IANA> name (also used by Mozilla, and |
668 | provided as an alias by Encode): C<Windows-31J>. |
a999c27c |
669 | |
670 | Encode separately supports C<Shift_JIS> and C<cp932>. |
671 | |
672 | =back |
673 | |
674 | =head1 Glossary |
675 | |
0ab8f81e |
676 | =over 4 |
a999c27c |
677 | |
678 | =item character repertoire |
679 | |
0ab8f81e |
680 | A collection of unique characters. A I<character> set in the strictest |
681 | sense. At this stage, characters are not numbered. |
a999c27c |
682 | |
683 | =item coded character set (CCS) |
684 | |
685 | A character set that is mapped in a way computers can use directly. |
0ab8f81e |
686 | Many character encodings, including EUC, fall in this category. |
a999c27c |
687 | |
688 | =item character encoding scheme (CES) |
689 | |
690 | An algorithm to map a character set to a byte sequence. You don't |
691 | have to be able to tell which character set a given byte sequence |
692 | belongs. 7-bit ISO-2022 is a CES but it cannot be a CCS. EUC is an |
693 | example of being both a CCS and CES. |
694 | |
f2a2953c |
695 | =item charset (in MIME context) |
696 | |
697 | has long been used in the meaning of C<encoding>, CES. |
698 | |
0ab8f81e |
699 | While the word combination C<character set> has lost this meaning |
700 | in MIME context since [RFC 2130], the C<charset> abbreviation has |
701 | retained it. This is how [RFC 2277] and [RFC 2278] bless C<charset>: |
f2a2953c |
702 | |
703 | This document uses the term "charset" to mean a set of rules for |
704 | mapping from a sequence of octets to a sequence of characters, such |
705 | as the combination of a coded character set and a character encoding |
706 | scheme; this is also what is used as an identifier in MIME "charset=" |
707 | parameters, and registered in the IANA charset registry ... (Note |
708 | that this is NOT a term used by other standards bodies, such as ISO). |
ab3374e4 |
709 | [RFC 2277] |
f2a2953c |
710 | |
a999c27c |
711 | =item EUC |
712 | |
0ab8f81e |
713 | Extended Unix Character. See ISO-2022. |
a999c27c |
714 | |
715 | =item ISO-2022 |
716 | |
0ab8f81e |
717 | A CES that was carefully designed to coexist with ASCII. There are a 7 |
718 | bit version and an 8 bit version. |
f2a2953c |
719 | |
0ab8f81e |
720 | The 7 bit version switches character set via escape sequence so it |
f2a2953c |
721 | cannot form a CCS. Since this is more difficult to handle in programs |
0ab8f81e |
722 | than the 8 bit version, the 7 bit version is not very popular except for |
723 | iso-2022-jp, the I<de facto> standard CES for e-mails. |
f2a2953c |
724 | |
0ab8f81e |
725 | The 8 bit version can form a CCS. EUC and ISO-8859 are two examples |
962111ca |
726 | thereof. Pre-5.6 perl could use them as string literals. |
a999c27c |
727 | |
728 | =item UCS |
729 | |
730 | Short for I<Universal Character Set>. When you say just UCS, it means |
0ab8f81e |
731 | I<Unicode>. |
a999c27c |
732 | |
733 | =item UCS-2 |
734 | |
735 | ISO/IEC 10646 encoding form: Universal Character Set coded in two |
736 | octets. |
737 | |
738 | =item Unicode |
739 | |
0ab8f81e |
740 | A character set that aims to include all character repertoires of the |
962111ca |
741 | world. Many character sets in various national as well as industrial |
f2a2953c |
742 | standards have become, in a way, just subsets of Unicode. |
a999c27c |
743 | |
744 | =item UTF |
745 | |
f2a2953c |
746 | Short for I<Unicode Transformation Format>. Determines how to map a |
0ab8f81e |
747 | Unicode character into a byte sequence. |
a999c27c |
748 | |
749 | =item UTF-16 |
750 | |
751 | A UTF in 16-bit encoding. Can either be in big endian or little |
0ab8f81e |
752 | endian. The big endian version is called UTF-16BE (equal to UCS-2 + |
753 | surrogate support) and the little endian version is called UTF-16LE. |
67d7b5ef |
754 | |
755 | =back |
5d030b67 |
756 | |
757 | =head1 See Also |
758 | |
5129552c |
759 | L<Encode>, |
760 | L<Encode::Byte>, |
a63c962f |
761 | L<Encode::CN>, L<Encode::JP>, L<Encode::KR>, L<Encode::TW>, |
5129552c |
762 | L<Encode::EBCDIC>, L<Encode::Symbol> |
e8c86ba6 |
763 | L<Encode::MIME::Header>, L<Encode::Guess> |
5d030b67 |
764 | |
a999c27c |
765 | =head1 References |
766 | |
0ab8f81e |
767 | =over 4 |
a999c27c |
768 | |
769 | =item ECMA |
770 | |
771 | European Computer Manufacturers Association |
772 | L<http://www.ecma.ch> |
773 | |
0ab8f81e |
774 | =over 4 |
a999c27c |
775 | |
0ab8f81e |
776 | =item ECMA-035 (eq C<ISO-2022>) |
a999c27c |
777 | |
778 | L<http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM> |
779 | |
0ab8f81e |
780 | The specification of ISO-2022 is available from the link above. |
a999c27c |
781 | |
782 | =back |
783 | |
784 | =item IANA |
785 | |
786 | Internet Assigned Numbers Authority |
787 | L<http://www.iana.org/> |
788 | |
0ab8f81e |
789 | =over 4 |
a999c27c |
790 | |
791 | =item Assigned Charset Names by IANA |
792 | |
793 | L<http://www.iana.org/assignments/character-sets> |
794 | |
795 | Most of the C<canonical names> in Encode derive from this list |
796 | so you can directly apply the string you have extracted from MIME |
448e90bb |
797 | header of mails and web pages. |
a999c27c |
798 | |
799 | =back |
800 | |
801 | =item ISO |
802 | |
803 | International Organization for Standardization |
804 | L<http://www.iso.ch/> |
805 | |
806 | =item RFC |
807 | |
962111ca |
808 | Request For Comments -- need I say more? |
0ab8f81e |
809 | L<http://www.rfc-editor.org/>, L<http://www.rfc.net/>, |
810 | L<http://www.faqs.org/rfcs/> |
a999c27c |
811 | |
812 | =item UC |
813 | |
814 | Unicode Consortium |
815 | L<http://www.unicode.org/> |
816 | |
0ab8f81e |
817 | =over 4 |
a999c27c |
818 | |
819 | =item Unicode Glossary |
820 | |
821 | L<http://www.unicode.org/glossary/> |
822 | |
962111ca |
823 | The glossary of this document is based upon this site. |
a999c27c |
824 | |
825 | =back |
826 | |
827 | =back |
828 | |
829 | =head2 Other Notable Sites |
830 | |
0ab8f81e |
831 | =over 4 |
a999c27c |
832 | |
833 | =item czyborra.com |
834 | |
f2a2953c |
835 | L<http://czyborra.com/> |
a999c27c |
836 | |
cf525c36 |
837 | Contains a lot of useful information, especially gory details of ISO |
a999c27c |
838 | vs. vendor mappings. |
839 | |
840 | =item CJK.inf |
841 | |
842 | L<http://www.oreilly.com/people/authors/lunde/cjk_inf.html> |
843 | |
844 | Somewhat obsolete (last update in 1996), but still useful. Also try |
845 | |
846 | L<ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf> |
847 | |
0ab8f81e |
848 | You will find brief info on C<EUC-CN>, C<GBK> and mostly on C<GB 18030>. |
a999c27c |
849 | |
f2a2953c |
850 | =item Jungshik Shin's Hangul FAQ |
851 | |
852 | L<http://jshin.net/faq> |
853 | |
0ab8f81e |
854 | And especially its subject 8. |
f2a2953c |
855 | |
856 | L<http://jshin.net/faq/qa8.html> |
857 | |
962111ca |
858 | A comprehensive overview of the Korean (C<KS *>) standards. |
f2a2953c |
859 | |
0ab8f81e |
860 | =item debian.org: "Introduction to i18n" |
861 | |
862 | A brief description for most of the mentioned CJK encodings is |
863 | contained in |
864 | L<http://www.debian.org/doc/manuals/intro-i18n/ch-codes.en.html> |
865 | |
f2a2953c |
866 | =back |
867 | |
868 | =head2 Offline sources |
869 | |
0ab8f81e |
870 | =over 4 |
f2a2953c |
871 | |
872 | =item C<CJKV Information Processing> by Ken Lunde |
873 | |
874 | CJKV Information Processing |
875 | 1999 O'Reilly & Associates, ISBN : 1-56592-224-7 |
876 | |
0ab8f81e |
877 | The modern successor of C<CJK.inf>. |
f2a2953c |
878 | |
0ab8f81e |
879 | Features a comprehensive coverage of CJKV character sets and |
f2a2953c |
880 | encodings along with many other issues faced by anyone trying |
881 | to better support CJKV languages/scripts in all the areas of |
882 | information processing. |
883 | |
0ab8f81e |
884 | To purchase this book, visit |
f2a2953c |
885 | L<http://www.oreilly.com/catalog/cjkvinfo/> |
0ab8f81e |
886 | or your favourite bookstore. |
f2a2953c |
887 | |
a999c27c |
888 | =back |
889 | |
5d030b67 |
890 | =cut |