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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Phillips, Ed. 3 Internet-Draft Quest Software 4 Expires: November 20, 2005 M. Davis, Ed. 5 IBM 6 May 19, 2005 8 Tags for Identifying Languages 9 draft-ietf-ltru-registry-02 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on November 20, 2005. 36 Copyright Notice 38 Copyright (C) The Internet Society (2005). 40 Abstract 42 This document describes the structure, content, construction, and 43 semantics of language tags for use in cases where it is desirable to 44 indicate the language used in an information object. It also 45 describes how to register values for use in language tags and the 46 creation of user defined extensions for private interchange. This 47 document obsoletes RFC 3066 (which replaced RFC 1766). 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 52 2. The Language Tag . . . . . . . . . . . . . . . . . . . . . . . 4 53 2.1 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 4 54 2.1.1 Length Considerations . . . . . . . . . . . . . . . . 6 55 2.2 Language Subtag Sources and Interpretation . . . . . . . . 7 56 2.2.1 Primary Language Subtag . . . . . . . . . . . . . . . 8 57 2.2.2 Extended Language Subtags . . . . . . . . . . . . . . 10 58 2.2.3 Script Subtag . . . . . . . . . . . . . . . . . . . . 10 59 2.2.4 Region Subtag . . . . . . . . . . . . . . . . . . . . 11 60 2.2.5 Variant Subtags . . . . . . . . . . . . . . . . . . . 12 61 2.2.6 Extension Subtags . . . . . . . . . . . . . . . . . . 13 62 2.2.7 Private Use Subtags . . . . . . . . . . . . . . . . . 14 63 2.2.8 Pre-Existing RFC 3066 Registrations . . . . . . . . . 15 64 2.2.9 Classes of Conformance . . . . . . . . . . . . . . . . 15 65 3. Registry Format and Maintenance . . . . . . . . . . . . . . . 17 66 3.1 Format of the IANA Language Subtag Registry . . . . . . . 17 67 3.2 Maintenance of the Registry . . . . . . . . . . . . . . . 21 68 3.3 Stability of IANA Registry Entries . . . . . . . . . . . . 23 69 3.4 Registration Procedure for Subtags . . . . . . . . . . . . 26 70 3.5 Possibilities for Registration . . . . . . . . . . . . . . 29 71 3.6 Extensions and Extensions Namespace . . . . . . . . . . . 31 72 3.7 Conversion of the RFC 3066 Language Tag Registry . . . . . 34 73 4. Formation and Processing of Language Tags . . . . . . . . . . 37 74 4.1 Choice of Language Tag . . . . . . . . . . . . . . . . . . 37 75 4.2 Meaning of the Language Tag . . . . . . . . . . . . . . . 39 76 4.3 Canonicalization of Language Tags . . . . . . . . . . . . 40 77 4.4 Considerations for Private Use Subtags . . . . . . . . . . 41 78 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 43 79 6. Security Considerations . . . . . . . . . . . . . . . . . . . 44 80 7. Character Set Considerations . . . . . . . . . . . . . . . . . 45 81 8. Changes from RFC 3066 . . . . . . . . . . . . . . . . . . . . 46 82 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 50 83 9.1 Normative References . . . . . . . . . . . . . . . . . . . 50 84 9.2 Informative References . . . . . . . . . . . . . . . . . . 51 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 52 86 A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 53 87 B. Examples of Language Tags (Informative) . . . . . . . . . . . 54 88 C. Example Registry . . . . . . . . . . . . . . . . . . . . . . . 57 89 Intellectual Property and Copyright Statements . . . . . . . . 61 91 1. Introduction 93 Human beings on our planet have, past and present, used a number of 94 languages. There are many reasons why one would want to identify the 95 language used when presenting or requesting information. 97 Information about a user's language preferences commonly needs to be 98 identified so that appropriate processing can be applied. For 99 example, the user's language preferences in a browser can be used to 100 select web pages appropriately. A choice of language preference can 101 also be used to select among tools (such as dictionaries) to assist 102 in the processing or understanding of content in different languages. 104 In addition, knowledge about the particular language used by some 105 piece of information content may be useful or even required by some 106 types of information processing; for example spell-checking, 107 computer-synthesized speech, Braille transcription, or high-quality 108 print renderings. 110 One means of indicating the language used is by labeling the 111 information content with a language identifier. These identifiers 112 can also be used to specify user preferences when selecting 113 information content, or for labeling additional attributes of content 114 and associated resources. 116 These identifiers can also be used to indicate additional attributes 117 of content that are closely related to the language. In particular, 118 it is often necessary to indicate specific information about the 119 dialect, writing system, or orthography used in a document or 120 resource, as these attributes may be important for the user to obtain 121 information in a form that they can understand, or important in 122 selecting appropriate processing resources for the given content. 124 This document specifies an identifier mechanism and a registration 125 function for values to be used with that identifier mechanism. It 126 also defines a mechanism for private use values and future extension. 128 This document replaces RFC 3066, which replaced RFC 1766. For a list 129 of changes in this document, see Section 8. 131 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 132 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 133 document are to be interpreted as described in RFC 2119 [10]. 135 2. The Language Tag 137 2.1 Syntax 139 The language tag is composed of one or more parts: A primary language 140 subtag and a (possibly empty) series of subsequent subtags. Subtags 141 are distinguished by their length, position in the subtag sequence, 142 and content, so that each type of subtag can be recognized solely by 143 these features. This makes it possible to construct a parser that 144 can extract and assign some semantic information to the subtags, even 145 if specific subtag values are not recognized. Thus a parser need not 146 have an up-to-date copy of the registered subtag values to perform 147 most searching and matching operations. 149 The syntax of this tag in ABNF [7] is: 151 Language-Tag = (lang 152 *("-" extlang) 153 ["-" script] 154 ["-" region] 155 *("-" variant) 156 *("-" extension) 157 ["-" privateuse]) 158 / privateuse ; private-use tag 159 / grandfathered ; grandfathered registrations 161 lang = 2*3ALPHA ; shortest ISO 639 code 162 / registered-lang 163 extlang = 3ALPHA ; reserved for future use 164 script = 4ALPHA ; ISO 15924 code 165 region = 2ALPHA ; ISO 3166 code 166 / 3DIGIT ; UN country number 167 variant = 5*8alphanum ; registered variants 168 / ( DIGIT 3alphanum ) 169 extension = singleton 1*("-" (2*8alphanum)) 170 privateuse = ("x"/"X") 1*("-" (1*8alphanum)) 171 singleton = %x41-57 / %x59-5A / %x61-77 / %x79-7A / DIGIT 172 ; "a"-"w" / "y"-"z" / "A"-"W" / "Y"-"Z" / "0"-"9" 173 ; Single letters: x/X is reserved for private use 174 registered-lang = 4*8ALPHA ; registered language subtag 175 grandfathered = 1*3ALPHA 1*2("-" (2*8alphanum)) 176 ; grandfathered registration 177 ; Note: i is the only singleton 178 ; that starts a grandfathered tag 179 alphanum = (ALPHA / DIGIT) ; letters and numbers 181 Figure 1: Language Tag ABNF 183 The character "-" is HYPHEN-MINUS (ABNF: %x2D). All subtags have a 184 maximum length of eight characters. Note that there is a subtlety in 185 the ABNF for 'variant': variants starting with a digit may be only 186 four characters long, while those starting with a letter must be at 187 least five characters long. 189 Whitespace is not permitted in a language tag. For examples of 190 language tags, see Appendix B. 192 Note that although [7] refers to octets, the language tags described 193 in this document are sequences of characters from the US-ASCII 194 repertoire. Language tags may be used in documents and applications 195 that use other encodings, so long as these encompass the US-ASCII 196 repertoire. An example of this would be an XML document that uses 197 the UTF-16LE [12] encoding of Unicode [20]. 199 The tags and their subtags, including private-use and extensions, are 200 to be treated as case insensitive: there exist conventions for the 201 capitalization of some of the subtags, but these should not be taken 202 to carry meaning. 204 For example: 206 o [ISO 639] [1] recommends that language codes be written in lower 207 case ('mn' Mongolian). 209 o [ISO 3166] [4] recommends that country codes be capitalized ('MN' 210 Mongolia). 212 o [ISO 15924] [3] recommends that script codes use lower case with 213 the initial letter capitalized ('Cyrl' Cyrillic). 215 However, in the tags defined by this document, the uppercase US-ASCII 216 letters in the range 'A' through 'Z' are considered equivalent and 217 mapped directly to their US-ASCII lowercase equivalents in the range 218 'a' through 'z'. Thus the tag "mn-Cyrl-MN" is not distinct from "MN- 219 cYRL-mn" or "mN-cYrL-Mn" (or any other combination) and each of these 220 variations conveys the same meaning: Mongolian written in the 221 Cyrillic script as used in Mongolia. 223 2.1.1 Length Considerations 225 Although neither the ABNF nor other guidelines in this document 226 provide a fixed upper limit on the number of subtags in a Language 227 Tag (and thus the upper bound on the size of a tag) and it is 228 possible to envision quite long and complex subtag sequences, in 229 practice these are rare because additional granularity in tags seldom 230 adds useful distinguishing information and because longer, more 231 granular tags interefere with the meaning, understanding, and 232 processing of language tags. 234 In particular, variant subtags SHOULD be used only with their 235 recommended prefix. In practice, this limits most tags to a sequence 236 of four subtags, and thus a maximum length of 26 characters 237 (excluding any extensions or private use sequences). This is because 238 subtags are limited to a length of eight characters and the extlang, 239 script, and region subtags are limited to even fewer characters. See 240 Section 4.1 for more information on selecting the most appropriate 241 Language Tag. 243 A conformant implementation MAY refuse to support the storage of 244 language tags which exceed a specified length. For an example, see 246 [RFC 2231] [22]. Any such limitation MUST be clearly documented, and 247 such documentation SHOULD include the disposition of any longer tags 248 (for example, whether an error value is generated or the language tag 249 is truncated). If truncation is permitted it MUST NOT permit a 250 subtag to be divided. 252 2.2 Language Subtag Sources and Interpretation 254 The namespace of language tags and their subtags is administered by 255 the Internet Assigned Numbers Authority (IANA) [13] according to the 256 rules in Section 5 of this document. The registry maintained by IANA 257 is the source for valid subtags: other standards referenced in this 258 section provide the source material for that registry. 260 Terminology in this section: 262 o Tag or tags refers to a complete language tag, such as 263 "fr-Latn-CA". Examples of tags in this document are enclosed in 264 double-quotes ("en-US"). 266 o Subtag refers to a specific section of a tag, delimited by hyphen, 267 such as the subtag 'Latn' in "fr-Latn-CA". Examples of subtags in 268 this document are enclosed in single quotes ('Latn'). 270 o Code or codes refers to values defined in external standards (and 271 which are used as subtags in this document). For example, 'Latn' 272 is an [ISO 15924] [3] script code which was used to define the 273 'Latn' script subtag for use in a language tag. Examples of codes 274 in this document are enclosed in single quotes ('en', 'Latn'). 276 The definitions in this section apply to the various subtags within 277 the language tags defined by this document, excepting those 278 "grandfathered" tags defined in Section 2.2.8. 280 Language tags are designed so that each subtag type has unique length 281 and content restrictions. These make identification of the subtag's 282 type possible, even if the content of the subtag itself is 283 unrecognized. This allows tags to be parsed and processed without 284 reference to the latest version of the underlying standards or the 285 IANA registry and makes the associated exception handling when 286 parsing tags simpler. 288 Subtags in the IANA registry that do not come from an underlying 289 standard can only appear in specific positions in a tag. 290 Specifically, they can only occur as primary language subtags or as 291 variant subtags. 293 Note that sequences of private-use and extension subtags MUST occur 294 at the end of the sequence of subtags and MUST NOT be interspersed 295 with subtags defined elsewhere in this document. 297 Single letter and digit subtags are reserved for current or future 298 use. These include the following current uses: 300 o The single letter subtag 'x' is reserved to introduce a sequence 301 of private-use subtags. The interpretation of any private-use 302 subtags is defined solely by private agreement and is not defined 303 by the rules in this section or in any standard or registry 304 defined in this document. 306 o All other single letter subtags are reserved to introduce 307 standardized extension subtag sequences as described in 308 Section 3.6. 310 The single letter subtag 'i' is used by some grandfathered tags, such 311 as "i-enochian", where it always appears in the first position and 312 cannot be confused with an extension. 314 2.2.1 Primary Language Subtag 316 The primary language subtag is the first subtag in a language tag 317 (with the exception of private-use and certain grandfathered tags) 318 and cannot be omitted. The following rules apply to the primary 319 language subtag: 321 1. All two character language subtags were defined in the IANA 322 registry according to the assignments found in the standard ISO 323 639 Part 1, "ISO 639-1:2002, Codes for the representation of 324 names of languages -- Part 1: Alpha-2 code" [ISO 639-1] [1], or 325 using assignments subsequently made by the ISO 639 Part 1 326 maintenance agency or governing standardization bodies. 328 2. All three character language subtags were defined in the IANA 329 registry according to the assignments found in ISO 639 Part 2, 330 "ISO 639-2:1998 - Codes for the representation of names of 331 languages -- Part 2: Alpha-3 code - edition 1" [ISO 639-2] [2], 332 or assignments subsequently made by the ISO 639 Part 2 333 maintenance agency or governing standardization bodies. 335 3. The subtags in the range 'qaa' through 'qtz' are reserved for 336 private use in language tags. These subtags correspond to codes 337 reserved by ISO 639-2 for private use. These codes MAY be used 338 for non-registered primary-language subtags (instead of using 339 private-use subtags following 'x-'). Please refer to Section 4.4 340 for more information on private use subtags. 342 4. All four character language subtags are reserved for possible 343 future standardization. 345 5. All language subtags of 5 to 8 characters in length in the IANA 346 registry were defined via the registration process in Section 3.4 347 and MAY be used to form the primary language subtag. At the time 348 this document was created, there were no examples of this kind of 349 subtag and future registrations of this type will be discouraged: 350 primary languages are STRONGLY RECOMMENDED for registration with 351 ISO 639 and proposals rejected by ISO 639/RA will be closely 352 scrutinized before they are registered with IANA. 354 6. The single character subtag 'x' as the primary subtag indicates 355 that the language tag consists solely of subtags whose meaning is 356 defined by private agreement. For example, in the tag "x-fr-CH", 357 the subtags 'fr' and 'CH' should not be taken to represent the 358 French language or the country of Switzerland (or any other value 359 in the IANA registry) unless there is a private agreement in 360 place to do so. See Section 4.4. 362 7. The single character subtag 'i' is used by some grandfathered 363 tags (see Section 2.2.8) such as "i-klingon" and "i-bnn". (Other 364 grandfathered tags have a primary language subtag in their first 365 position) 367 8. Other values MUST NOT be assigned to the primary subtag except by 368 revision or update of this document. 370 Note: For languages that have both an ISO 639-1 two character code 371 and an ISO 639-2 three character code, only the ISO 639-1 two 372 character code is defined in the IANA registry. 374 Note: For languages that have no ISO 639-1 two character code and for 375 which the ISO 639-2/T (Terminology) code and the ISO 639-2/B 376 (Bibliographic) codes differ, only the Terminology code is defined in 377 the IANA registry. At the time this document was created, all 378 languages that had both kinds of three character code were also 379 assigned a two character code; it is not expected that future 380 assignments of this nature will occur. 382 Note: To avoid problems with versioning and subtag choice as 383 experienced during the transition between RFC 1766 and RFC 3066, as 384 well as the canonical nature of subtags defined by this document, the 385 ISO 639 Registration Authority Joint Advisory Committee (ISO 639/ 386 RA-JAC) has included the following statement in [16]: 388 "A language code already in ISO 639-2 at the point of freezing ISO 389 639-1 shall not later be added to ISO 639-1. This is to ensure 390 consistency in usage over time, since users are directed in Internet 391 applications to employ the alpha-3 code when an alpha-2 code for that 392 language is not available." 394 In order to avoid instability of the canonical form of tags, if a two 395 character code is added to ISO 639-1 for a language for which a three 396 character code was already included in ISO 639-2, the two character 397 code will not be added as a subtag in the registry. See Section 3.3. 399 For example, if some content were tagged with 'haw' (Hawaiian), which 400 currently has no two character code, the tag would not be invalidated 401 if ISO 639-1 were to assign a two character code to the Hawaiian 402 language at a later date. 404 For example, one of the grandfathered IANA registrations is 405 "i-enochian". The subtag 'enochian' could be registered in the IANA 406 registry as a primary language subtag (assuming that ISO 639 does not 407 register this language first), making tags such as "enochian-AQ" and 408 "enochian-Latn" valid. 410 2.2.2 Extended Language Subtags 412 The following rules apply to the extended language subtags: 414 1. Three letter subtags immediately following the primary subtag are 415 reserved for future standardization, anticipating work that is 416 currently under way on ISO 639. 418 2. Extended language subtags MUST follow the primary subtag and 419 precede any other subtags. 421 3. There MAY be any additional number of extended language subtags. 423 4. Extended language subtags will not be registered except by 424 revision of this document. 426 5. Extended language subtags MUST NOT be used to form language tags 427 except by revision of this document. 429 Example: In a future revision or update of this document, the tag 430 "zh-gan" (registered under RFC 3066) might become a valid non- 431 grandfathered (that is, redundant) tag in which the subtag 'gan' 432 might represent the Chinese dialect 'Gan'. 434 2.2.3 Script Subtag 436 The following rules apply to the script subtags: 438 1. All four character subtags were defined according to ISO 15924 439 [3]--"Codes for the representation of the names of scripts": 440 alpha-4 script codes, or subsequently assigned by the ISO 15924 441 maintenance agency or governing standardization bodies, denoting 442 the script or writing system used in conjunction with this 443 language. 445 2. Script subtags MUST immediately follow the primary language 446 subtag and all extended language subtags and MUST occur before 447 any other type of subtag described below. 449 3. The script subtags 'Qaaa' through 'Qabx' are reserved for private 450 use in language tags. These subtags correspond to codes reserved 451 by ISO 15924 for private use. These codes MAY be used for non- 452 registered script values. Please refer to Section 4.4 for more 453 information on private-use subtags. 455 4. Script subtags cannot be registered using the process in 456 Section 3.4 of this document. Variant subtags may be considered 457 for registration for that purpose. 459 Example: "de-Latn" represents German written using the Latin script. 461 2.2.4 Region Subtag 463 The following rules apply to the region subtags: 465 1. The region subtag defines language variations used in a specific 466 region, geographic, or political area. Region subtags MUST 467 follow any language, extended language, or script subtags and 468 MUST precede all other subtags. 470 2. All two character subtags following the primary subtag were 471 defined in the IANA registry according to the assignments found 472 in ISO 3166 [4]--"Codes for the representation of names of 473 countries and their subdivisions - Part 1: Country 474 codes"--alpha-2 country codes or assignments subsequently made by 475 the ISO 3166 maintenance agency or governing standardization 476 bodies. 478 3. All three character codes consisting of digit (numeric) 479 characters were defined in the IANA registry according to the 480 assignments found in UN Standard Country or Area Codes for 481 Statistical Use [5] or assignments subsequently made by the 482 governing standards body. Note that not all of the UN M.49 codes 483 are defined in the IANA registry: 485 A. UN numeric codes assigned to 'macro-geographical 486 (continental)' or sub-regions not associated with an assigned 487 ISO 3166 alpha-2 code _are_ defined. 489 B. UN numeric codes for 'economic groupings' or 'other 490 groupings' are _not_ defined in the IANA registry and MUST 491 NOT be used to form language tags. 493 C. UN numeric codes for countries with ambiguous ISO 3166 494 alpha-2 codes as defined in Section 3.3 are defined in the 495 registry and are canonical for the given country or region 496 defined. 498 D. The alphanumeric codes in Appendix X of the UN document are 499 _not_ defined and MUST NOT be used to form language tags. 500 (At the time this document was created these values match the 501 ISO 3166 alpha-2 codes.) 503 4. There may be at most one region subtag in a language tag. 505 5. The region subtags 'AA', 'QM'-'QZ', 'XA'-'XZ', and 'ZZ' are 506 reserved for private use in language tags. These subtags 507 correspond to codes reserved by ISO 3166 for private use. These 508 codes MAY be used for private use region subtags (instead of 509 using a private-use subtag sequence). Please refer to 510 Section 4.4 for more information on private use subtags. 512 "de-CH" represents German ('de') as used in Switzerland ('CH'). 514 "sr-Latn-CS" represents Serbian ('sr') written using Latin script 515 ('Latn') as used in Serbia and Montenegro ('CS'). 517 "es-419" represents Spanish ('es') as used in the UN-defined Latin 518 America and Caribbean region ('419'). 520 2.2.5 Variant Subtags 522 The following rules apply to the variant subtags: 524 1. Variant subtags are not associated with any external standard. 525 Variant subtags and their meanings are defined by the 526 registration process defined in Section 3.4. 528 2. Variant subtags MUST follow all of the other defined subtags, but 529 precede any extension or private-use subtag sequences. 531 3. More than one variant MAY be used to form the language tag. 533 4. Variant subtags MUST be registered with IANA according to the 534 rules in Section 3.4 of this document before being used to form 535 language tags. In order to distinguish variants from other types 536 of subtags, registrations must meet the following length and 537 content restrictions: 539 1. Variant subtags that begin with a letter (a-z, A-Z) MUST be 540 at least five characters long. 542 2. Variant subtags that begin with a digit (0-9) MUST be at 543 least four characters long. 545 "en-scouse" represents the Scouse dialect of English. 547 "de-CH-1996" represents German as used in Switzerland and as written 548 using the spelling reform beginning in the year 1996 C.E. 550 2.2.6 Extension Subtags 552 The following rules apply to extensions: 554 1. Extension subtags are separated from the other subtags defined 555 in this document by a single-letter subtag ("singleton"). The 556 singleton MUST be one allocated to a registration authority via 557 the mechanism described in Section 3.6 and cannot be the letter 558 'x', which is reserved for private-use subtag sequences. 560 2. Note: Private-use subtag sequences starting with the singleton 561 subtag 'x' are described below. 563 3. An extension MUST follow at least a primary language subtag. 564 That is, a language tag cannot begin with an extension. 565 Extensions extend language tags, they do not override or replace 566 them. For example, "a-value" is not a well-formed language tag, 567 while "de-a-value" is. 569 4. Each singleton subtag MUST appear at most one time in each tag 570 (other than as a private-use subtag). That is, singleton 571 subtags MUST NOT be repeated. For example, the tag "en-a-bbb-a- 572 ccc" is invalid because the subtag 'a' appears twice. Note that 573 the tag "en-a-bbb-x-a-ccc" is valid because the second 574 appearance of the singleton 'a' is in a private use sequence. 576 5. Extension subtags MUST meet all of the requirements for the 577 content and format of subtags defined in this document. 579 6. Extension subtags MUST meet whatever requirements are set by the 580 document that defines their singleton prefix and whatever 581 requirements are provided by the maintaining authority. 583 7. Each extension subtag MUST be from two to eight characters long 584 and consist solely of letters or digits, with each subtag 585 separated by a single '-'. 587 8. Each singleton MUST be followed by at least one extension 588 subtag. For example, the tag "tlh-a-b-foo" is invalid because 589 the first singleton 'a' is followed immediately by another 590 singleton 'b'. 592 9. Extension subtags MUST follow all language, extended language, 593 script, region and variant subtags in a tag. 595 10. All subtags following the singleton and before another singleton 596 are part of the extension. Example: In the tag "fr-a-Latn", the 597 subtag 'Latn' does not represent the script subtag 'Latn' 598 defined in the IANA Language Subtag Registry. Its meaning is 599 defined by the extension 'a'. 601 11. In the event that more than one extension appears in a single 602 tag, the tag SHOULD be canonicalized as described in 603 Section 4.3. 605 For example, if the prefix singleton 'r' and the shown subtags were 606 defined, then the following tag would be a valid example: "en-Latn- 607 GB-boont-r-extended-sequence-x-private" 609 2.2.7 Private Use Subtags 611 The following rules apply to private-use subtags: 613 1. Private-use subtags are separated from the other subtags defined 614 in this document by the reserved single-character subtag 'x'. 616 2. Private-use subtags MUST follow all language, extended language, 617 script, region, variant, and extension subtags in the tag. 618 Another way of saying this is that all subtags following the 619 singleton 'x' MUST be considered private use. Example: The 620 subtag 'US' in the tag "en-x-US" is a private use subtag. 622 3. A tag MAY consist entirely of private-use subtags. 624 4. No source is defined for private use subtags. Use of private use 625 subtags is by private agreement only. 627 For example: Users who wished to utilize SIL Ethnologue for 628 identification might agree to exchange tags such as "az-Arab-x-AZE- 629 derbend". This example contains two private-use subtags. The first 630 is 'AZE' and the second is 'derbend'. 632 2.2.8 Pre-Existing RFC 3066 Registrations 634 Existing IANA-registered language tags from RFC 1766 and/or RFC 3066 635 maintain their validity. IANA will maintain these tags in the 636 registry under either the "grandfathered" or "redundant" type. For 637 more information see Section 3.7. 639 It is important to note that all language tags formed under the 640 guidelines in this document were either legal, well-formed tags or 641 could have been registered under RFC 3066. 643 2.2.9 Classes of Conformance 645 Implementations may wish to express their level of conformance with 646 the rules and practices described in this document. There are 647 generally two classes of conforming implementations: "well-formed" 648 processors and "validating" processors. Claims of conformance SHOULD 649 explicitly reference one of these definitions. 651 An implementation that claims to check for well-formed language tags 652 MUST: 654 o Check that the tag and all of its subtags, including extension and 655 private-use subtags, conform to the ABNF or that the tag is on the 656 list of grandfathered tags. 658 o Check that singleton subtags that identify extensions do not 659 repeat. For example, the tag "en-a-xx-b-yy-a-zz" is not well- 660 formed. 662 Well-formed processors are strongly encouraged to implement the 663 canonicalization rules contained in Section 4.3. 665 An implementation that claims to be validating MUST: 667 o Check that the tag is well-formed. 669 o Specify the particular registry date for which the implementation 670 performs validation of subtags. 672 o Check that either the tag is a grandfathered tag, or that all 673 language, script, region, and variant subtags consist of valid 674 codes for use in language tags according to the IANA registry as 675 of the particular date specified by the implementation. 677 o Specify which, if any, extension RFCs as defined in Section 3.6 678 are supported, including version, revision, and date. 680 o For any such extensions supported, check that all subtags used in 681 that extension are valid. 683 o If the processor generates tags, it MUST do so in canonical form, 684 including any supported extensions, as defined in Section 4.3. 686 3. Registry Format and Maintenance 688 This section defines the Language Subtag Registry and the maintenance 689 and update procedures associated with it. 691 The language subtag registry will be maintained so that, except for 692 extension subtags, it is possible to validate all of the subtags that 693 appear in a language tag under the provisions of this document or its 694 revisions or successors. In addition, the meaning of the various 695 subtags will be unambiguous and stable over time. (The meaning of 696 private-use subtags, of course, is not defined by the IANA registry.) 698 The registry defined under this document contains a comprehensive 699 list of all of the subtags valid in language tags. This allows 700 implementers a straightforward and reliable way to validate language 701 tags. 703 3.1 Format of the IANA Language Subtag Registry 705 The IANA Language Subtag Registry ("the registry") will consist of a 706 text file that is machine readable in the format described in this 707 section, plus copies of the registration forms approved by the 708 Language Subtag Reviewer in accordance with the process described in 709 Section 3.4. With the exception of the registration forms for 710 grandfathered and redundant tags, no registration records will be 711 maintained for the initial set of subtags. 713 The registry will be in a modified record-jar format text file [17]. 714 Lines are limited to 72 characters, including all whitespace. 716 Records are separated by lines containing only the sequence "%%" 717 (%x25.25). 719 Each field can be viewed as a single, logical line of ASCII 720 characters, comprising a field-name and a field-body separated by a 721 COLON character (%x3A). For convenience, the field-body portion of 722 this conceptual entity can be split into a multiple-line 723 representation; this is called "folding". The format of the registry 724 is described by the following ABNF (per [7]): 726 registry = record *("%%" CRLF record) 727 record = 1*( field-name *SP ":" *SP field-body CRLF ) 728 field-name = *(ALPHA / DIGIT / "-") 729 field-body = *(ASCCHAR/LWSP) 730 ASCCHAR = %x21-25 / %x27-7E / UNICHAR ; Note: AMPERSAND is %x26 731 UNICHAR = "&#x" 2*6HEXDIG ";" 733 The sequence '..' (%x2E.2E) in a field-body denotes a range of 734 values. Such a range represents all subtags of the same length that 735 are alphabetically within that range, including the values explicitly 736 mentioned. For example 'a..c' denotes the values 'a', 'b', and 'c'. 738 Characters from outside the US-ASCII repertoire, as well as the 739 AMPERSAND character ("&", %x26) when it occurs in a field-body are 740 represented by a "Numeric Character Reference" using hexadecimal 741 notation in the style used by XML 1.0 [18] (see 742 ). This consists of the 743 sequence "&#x" (%x26.23.78) followed by a hexadecimal representation 744 of the character's code point in ISO/IEC 10646 [6] followed by a 745 closing semicolon (%x3B). For example, the EURO SIGN, U+20AC, would 746 be represented by the sequence "€". Note that the hexadecimal 747 notation may have between two and six digits. 749 All fields whose field-body contains a date value use the "full-date" 750 format specified in RFC 3339 [14]. For example: "2004-06-28" 751 represents June 28, 2004 in the Gregorian calendar. 753 The first record in the file contains the single field whose field- 754 name is "File-Date" and whose field-body contains the last 755 modification date of the registry: 757 File-Date: 2004-06-28 758 %% 760 Subsequent records represent subtags in the registry. Each of the 761 fields in each record MUST occur no more than once, unless otherwise 762 noted below. Each record MUST contain the following fields: 764 o 'Type' 766 * Type's field-value MUST consist of one of the following 767 strings: "language", "extlang", "script", "region", "variant", 768 "grandfathered", and "redundant" and denotes the type of tag or 769 subtag. 771 o Either 'Subtag' or 'Tag' 773 * Subtag's field-value contains the subtag being defined. This 774 field MUST only appear in records of whose Type has one of 775 these values: "language", "extlang", "script", "region", or 776 "variant". 778 * Tag's field-value contains a complete language tag. This field 779 MUST only appear in records whose Type has one of these values: 780 "grandfathered" or "redundant". 782 o Description 784 * Description's field-value contains a non-normative description 785 of the subtag or tag. 787 o Added 789 * Added's field-value contains the date the record was added to 790 the registry. 792 The 'Subtag' or 'Tag' field MUST use lowercase letters to form the 793 subtag or tag, with two exceptions. Subtags whose 'Type' field is 794 'script' (in other words, subtags defined by ISO 15924) MUST use 795 titlecase. Subtags whose 'Type' field is 'region' (in other words, 796 subtags defined by ISO 3166) MUST use uppercase. These exceptions 797 mirror the use of case in the underlying standards. 799 The field 'Description' MAY appear more than one time. At least one 800 of the 'Description' fields must contain a description of the tag 801 being registered written or transcribed into the Latin script; the 802 same or additional fields may also include a description in a non- 803 Latin script. The 'Description' field is used for identification 804 purposes and should not be taken to represent the actual native name 805 of the language or variation or to be in any particular language. 806 Most descriptions are taken directly from source standards such as 807 ISO 639 or ISO 3166. 809 Note: Descriptions in registry entries that correspond to ISO 639, 810 ISO 15924, ISO 3166 or UN M.49 codes are intended only to indicate 811 the meaning of that identifier as defined in the source standard at 812 the time it was added to the registry. The description does not 813 replace the content of the source standard itself. The descriptions 814 are not intended to be the English localized names for the subtags. 815 Localization or translation of language tag and subtag descriptions 816 is out of scope of this document. 818 Each record MAY also contain the following fields: 820 o Canonical 822 * For fields of type 'language', 'extlang', 'script', 'region', 823 and 'variant', a canonical mapping of this record to a subtag 824 record of the same 'Type'. 826 * For fields of type 'grandfathered' and 'redundant', a canonical 827 mapping to a complete language tag. 829 o Deprecated 831 * Deprecated's field-value contains the date the record was 832 deprecated. 834 o Recommended-Prefix 836 * Recommended-Prefix's field-value contains a language tag with 837 which this subtag may be used to form a new language tag, 838 perhaps with other subtags as well. This field MUST only 839 appear in records whose 'Type' field-value is 'variant' or 840 'extlang'. For example, the 'Recommended-Prefix' for the 841 variant 'scouse' is 'en', meaning that the tags "en-scouse" and 842 "en-GB-scouse" might be appropriate while the tag "is-scouse" 843 is not. 845 o Comments 847 * Comments contains additional information about the subtag, as 848 deemed appropriate for understanding the registry and 849 implementing language tags using the subtag or tag. 851 o Suppress-Script 853 * Suppress-Script contains a script subtag that SHOULD NOT be 854 used to form language tags with the associated primary language 855 subtag. This field MUST only appear in records whose 'Type' 856 field-value is 'language'. See Section 4.1. 858 The field 'Canonical' SHALL NOT be added to any record already in the 859 registry. The field 'Canonical' SHALL NOT be modified except for 860 records of type "grandfathered": therefore a subtag whose record 861 contains no canonical mapping when the record is created is a 862 canonical form and will remain so. 864 The 'Canonical' field in records of type "grandfathered" and 865 "redundant" contains whole language tags that are STRONGLY 866 RECOMMENDED for use in place of the record's value. In many cases 867 the mappings were created by deprecation of the tags during the 868 period before this document was adopted. For example, the tag "no- 869 nyn" was deprecated in favor of the ISO 639-1 defined language code 870 'nn'. 872 Note that a record that has a 'Canonical' field MUST have a 873 'Deprecated' field also (although the converse is not true). 875 The field 'Deprecated' MAY be added to any record via the maintenance 876 process described in Section 3.2 or via the registration process 877 described in Section 3.4. Usually the addition of a 'Deprecated' 878 field is due to the action of one of the standards bodies, such as 879 ISO 3166, withdrawing a code. In some historical cases it may not 880 have been possible to reconstruct the original deprecation date. 881 For these cases, an approximate date appears in the registry. 882 Although valid in language tags, subtags and tags with a 'Deprecated' 883 field are deprecated and validating processors SHOULD NOT generate 884 these subtags. Note that a record that contains a 'Deprecated' field 885 and no corresponding 'Canonical' field has no replacement mapping. 887 The field 'Recommended-Prefix' MAY appear more than once per record. 888 Additional fields of this type MAY be added to a record via the 889 registration process. The field-value of of this field consists of a 890 language tag that is RECOMMENDED for use as a prefix for this subtag. 891 For example, the variant subtag 'scouse' has a recommended prefix of 892 "en". This means that tags starting with the prefix "en-" are most 893 appropriate with this subtag, so "en-Latn-scouse" and "en-GB-scouse" 894 are both acceptable, while the tag "fr-scouse" is probably an 895 inappropriate choice. 897 The field of type Recommended-Prefix MUST NOT be removed from any 898 record. The field-value for this type of field MUST NOT be modified. 900 The field 'Comments' MAY appear more than once per record. This 901 field MAY be inserted or changed via the registration process and no 902 guarantee of stability is provided. The content of this field is not 903 restricted, except by the need to register the information, the 904 suitability of the request, and by reasonable practical size 905 limitations. Long screeds about a particular subtag are frowned 906 upon. 908 The field 'Suppress-Script' MUST only appear in records whose 'Type' 909 field-value is 'language'. This field may appear at most one time in 910 a record. This field indicates a script used to write the 911 overwhelming majority of documents for the given language and which 912 therefore adds no distinguishing information to a language tag. It 913 helps ensure greater compatibility between the language tags 914 generated according to the rules in this document and language tags 915 and tag processors or consumers based on RFC 3066. For example, 916 virtually all Icelandic documents are written in the Latin script, 917 making the subtag 'Latn' redundant in the tag "is-Latn". 919 For examples of registry entries and their format, see Appendix C. 921 3.2 Maintenance of the Registry 923 Maintenance of the registry requires that as new codes are assigned 924 by ISO 639, ISO 15924, and ISO 3166, the Language Subtag Reviewer 925 will evaluate each assignment, determine whether it conflicts with 926 existing registry entries, and submit the information to IANA for 927 inclusion in the registry. If an assignment takes place and the 928 Language Subtag Reviewer does not do this in a timely manner, then 929 any interested party may use the procedure in Section 3.4 to register 930 the appropriate update. 932 Note: The redundant and grandfathered entries together are the 933 complete list of tags registered under RFC 3066 [23]. The redundant 934 tags are those that can now be formed using the subtags defined in 935 the registry together with the rules of Section 2.2. The 936 grandfathered entries are those that can never be legal under those 937 same provisions. The items in both lists are permanent and stable, 938 although grandfathered items may be deprecated over time. Refer to 939 Section 3.7 for more information. 941 RFC 3066 tags that were deprecated prior to the adoption of this 942 document are part of the list of grandfathered tags and their 943 component subtags were not included as registered variants (although 944 they remain eligible for registration). For example, the tag "art- 945 lojban" was deprecated in favor of the language subtag 'jbo'. 947 The Language Subtag Reviewer MUST ensure that new subtags meet the 948 requirements in Section 4.1 or submit an appropriate alternate subtag 949 as described in that section. If a change or addition to the 950 registry is required, the Language Subtag Reviewer will prepare the 951 complete record, including all fields, and forward it to IANA for 952 insertion into the registry. If this represents a new subtag, then 953 the message will indicate that this represents an INSERTION of a 954 record. If this represents a change to an existing subtag, then the 955 message must indicate that this represents a MODIFICATION, as shown 956 in the following example: 958 LANGUAGE SUBTAG MODIFICATION 959 File-Date: 2005-01-02 960 %% 961 Type: variant 962 Subtag: nedis 963 Description: Natisone dialect 964 Description: Nadiza dialect 965 Added: 2003-10-09 966 Recommended-Prefix: sl 967 Comments: This is a comment shown 968 as an example. 969 %% 971 Figure 4 973 Whenever an entry is created or modified in the registry, the 'File- 974 Date' record at the start of the registry is updated to reflect the 975 most recent modification date in the RFC 3339 [14] "full-date" 976 format. 978 Values in the 'Subtag' field must be lowercase except as provided for 979 in Section 3.1. 981 3.3 Stability of IANA Registry Entries 983 The stability of entries and their meaning in the registry is 984 critical to the long term stability of language tags. The rules in 985 this section guarantee that a specific language tag's meaning is 986 stable over time and will not change and that the choice of language 987 tag for specific content is also stable over time. 989 These rules specifically deal with how changes to codes (including 990 withdrawal and deprecation of codes) maintained by ISO 639, ISO 991 15924, ISO 3166, and UN M.49 are reflected in the IANA Language 992 Subtag Registry. Assignments to the IANA Language Subtag Registry 993 MUST follow the following stability rules: 995 o Values in the fields 'Type', 'Subtag', 'Tag', 'Added' and 996 'Canonical' MUST NOT be changed and are guaranteed to be stable 997 over time. 999 o Values in the 'Description' field MUST NOT be changed in a way 1000 that would invalidate previously-existing tags. They may be 1001 broadened somewhat in scope, changed to add information, or 1002 adapted to the most common modern usage. For example, countries 1003 occasionally change their official names: an historical example of 1004 this would be "Upper Volta" changing to "Burkina Faso". 1006 o Values in the field 'Recommended-Prefix' MAY be added via the 1007 registration process. 1009 o Values in the field 'Recommended-Prefix' MAY be modified, so long 1010 as the modifications broaden the set of recommended prefixes. 1011 That is, a recommended prefix MAY be replaced by one of its own 1012 prefixes. For example, the prefix "en-US" could be replaced by 1013 "en", but not by the ranges "en-Latn", "fr", or "en-US-boont". 1015 o Values in the field 'Recommended-Prefix' MUST NOT be removed. 1017 o The field 'Comments' MAY be added, changed, modified, or removed 1018 via the registration process or any of the processes or 1019 considerations described in this section. 1021 o The field 'Suppress-Script' MAY be added or removed via the 1022 registration process. 1024 o Codes assigned by ISO 639, ISO 15924, and ISO 3166 that do not 1025 conflict with existing subtags of the associated type and whose 1026 meaning is not the same as an existing subtag of the same type are 1027 entered into the IANA registry as new records and their value is 1028 canonical for the meaning assigned to them. 1030 o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that are 1031 withdrawn by their respective maintenance or registration 1032 authority remain valid in language tags. The registration process 1033 MAY be used to add a note indicating the withdrawal of the code by 1034 the respective standard. 1036 o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that do not 1037 conflict with existing subtags of the associated type but which 1038 represent the same meaning as an existing subtag of that type are 1039 entered into the IANA registry as new records. The field 1040 'canonical value' for that record MUST contain the existing subtag 1041 of the same meaning 1043 Example If ISO 3166 were to assign the code 'IM' to represent the 1044 value "Isle of Man" (represented in the IANA registry by the UN 1045 M.49 code '833'), '833' remains the canonical subtag and 'IM' 1046 would be assigned '833' as a canonical value. This prevents 1047 tags that are in canonical form from becoming non-canonical. 1049 Example If the tag 'enochian' were registered as a primary 1050 language subtag and ISO 639 subsequently assigned an alpha-3 1051 code to the same language, the new ISO 639 code would be 1052 entered into the IANA registry as a subtag with a canonical 1053 mapping to 'enochian'. The new ISO code can be used, but it is 1054 not canonical. 1056 o Codes assigned by ISO 639, ISO 15924, or ISO 3166 that conflict 1057 with existing subtags of the associated type MUST NOT be entered 1058 into the registry. The following additional considerations apply: 1060 * For ISO 639 codes, if the newly assigned code's meaning is not 1061 represented by a subtag in the IANA registry, the Language 1062 Subtag Reviewer, as described in Section 3.4, shall prepare a 1063 proposal for entering in the IANA registry as soon as practical 1064 a registered language subtag as an alternate value for the new 1065 code. The form of the registered language subtag will be at 1066 the discretion of the Language Subtag Reviewer and must conform 1067 to other restrictions on language subtags in this document. 1069 * For all subtags whose meaning is derived from an external 1070 standard (i.e. ISO 639, ISO 15924, ISO 3166, or UN M.49), if a 1071 new meaning is assigned to an existing code and the new meaning 1072 broadens the meaning of that code, then the meaning for the 1073 associated subtag MAY be changed to match. The meaning of a 1074 subtag MUST NOT be narrowed, however, as this can result in an 1075 unknown proportion of the existing uses of a subtag becoming 1076 invalid. Note: ISO 639 MA/RA has adopted a similar stability 1077 policy. 1079 * For ISO 15924 codes, if the newly assigned code's meaning is 1080 not represented by a subtag in the IANA registry, the Language 1081 Subtag Reviewer, as described in Section 3.4, shall prepare a 1082 proposal for entering in the IANA registry as soon as practical 1083 a registered variant subtag as an alternate value for the new 1084 code. The form of the registered variant subtag will be at the 1085 discretion of the Language Subtag Reviewer and must conform to 1086 other restrictions on variant subtags in this document. 1088 * For ISO 3166 codes, if the newly assigned code's meaning is 1089 associated with the same UN M.49 code as another 'region' 1090 subtag, then the existing region subtag remains as the 1091 canonical entry for that region and no new entry is created. A 1092 comment MAY be added to the existing region subtag indicating 1093 the relationship to the new ISO 3166 code. 1095 * For ISO 3166 codes, if the newly assigned code's meaning is 1096 associated with a UN M.49 code that is not represented by an 1097 existing region subtag, then then the Language Subtag Reviewer, 1098 as described in Section 3.4, shall prepare a proposal for 1099 entering the appropriate numeric UN country code as an entry in 1100 the IANA registry. 1102 * For ISO 3166 codes, if there is no associated UN numeric code, 1103 then the Language Subtag Reviewer SHALL petition the UN to 1104 create one. If there is no response from the UN within ninety 1105 days of the request being sent, the Language Subtag Reviewer 1106 shall prepare a proposal for entering in the IANA registry as 1107 soon as practical a registered variant subtag as an alternate 1108 value for the new code. The form of the registered variant 1109 subtag will be at the discretion of the Language Subtag 1110 Reviewer and must conform to other restrictions on variant 1111 subtags in this document. This situation is very unlikely to 1112 ever occur. 1114 o Stability provisions apply to grandfathered tags with this 1115 exception: should all of the subtags in a grandfathered tag become 1116 valid subtags in the IANA registry, then the grandfathered tag 1117 MUST be marked as redundant. Note that this will not affect 1118 language tags that match the grandfathered tag, since these tags 1119 will now match valid generative subtag sequences. For example, if 1120 the subtag 'gan' in the language tag "zh-gan" were to be 1121 registered as an extended language subtag, then the grandfathered 1122 tag "zh-gan" would be deprecated (but existing content or 1123 implementations that use "zh-gan" would remain valid). 1125 3.4 Registration Procedure for Subtags 1127 The procedure given here MUST be used by anyone who wants to use a 1128 subtag not currently in the IANA Language Subtag Registry. 1130 Only subtags of type 'language' and 'variant' will be considered for 1131 independent registration of new subtags. Handling of subtags 1132 required for stability and subtags required to keep the registry 1133 synchronized with ISO 639, ISO 15924, ISO 3166, and UN M.49 within 1134 the limits defined by this document are described in Section 3.2. 1135 Stability provisions are described in Section 3.3. 1137 This procedure MAY also be used to register or alter the information 1138 for the "Description", "Comments", "Deprecated", or "Recommended- 1139 Prefix" fields in a subtag's record as described in Figure 7. 1140 Changes to all other fields in the IANA registry are NOT permitted. 1142 Registering a new subtag or requesting modifications to an existing 1143 tag or subtag starts with the requster filling out the registration 1144 form reproduced below. Note that each response is not limited in 1145 size and should take the room necessary to adequately describe the 1146 registration. The fields in the "Record Requested" section SHOULD 1147 follow the requirements in Section 3.1. 1149 LANGUAGE SUBTAG REGISTRATION FORM 1150 1. Name of requester: 1151 2. E-mail address of requester: 1152 3. Record Requested: 1154 Type: 1155 Subtag: 1156 Description: 1157 Recommended-Prefix: 1158 Canonical: 1159 Deprecated: 1160 Suppress-Script: 1161 Comments: 1163 4. Intended meaning of the subtag: 1164 5. Reference to published description 1165 of the language (book or article): 1166 6. Any other relevant information: 1168 Figure 5 1170 The subtag registration form MUST be sent to 1171 for a two week review period before it can 1172 be submitted to IANA. (This is an open list. Requests to be added 1173 should be sent to .) 1175 Variant subtags are generally registered for use with a particular 1176 range of language tags. For example, the subtag 'scouse' is intended 1177 for use with language tags that start with the primary language 1178 subtag "en", since Scouse is a dialect of English. Thus the subtag 1179 'scouse' could be included in tags such as "en-Latn-scouse" or "en- 1180 GB-scouse". This information is stored in the "Recommended-Prefix" 1181 field in the registry. Variant registration requests are REQUIRED to 1182 include at least one "Recommended-Prefix" field in the registration 1183 form. 1185 Any subtag MAY be incorporated into a variety of language tags, 1186 according to the rules of Section 2.1, including tags that do not 1187 match any of the recommended prefixes of the registered subtag. 1188 (Note that this is probably a poor choice.) This makes validation 1189 simpler and thus more uniform across implementations, and does not 1190 require the registration of a separate subtag for the same purpose 1191 and meaning but a different recommended prefix. 1193 The recommended prefixes for a given registered subtag will be 1194 maintained in the IANA registry as a guide to usage. If it is 1195 necessary to add an additional prefix to that list for an existing 1196 language tag, that can be done by filing an additional registration 1197 form. In that form, the "Any other relevant information:" field 1198 should indicate that it is the addition of an additional recommended 1199 prefix. 1201 Requests to add a recommended prefix to a subtag that imply a 1202 different semantic meaning will probably be rejected. For example, a 1203 request to add the prefix "de" to the subtag 'nedis' so that the tag 1204 "de-nedis" represented some German dialect would be rejected. The 1205 'nedis' subtag represents a particular Slovenian dialect and the 1206 additional registration would change the semantic meaning assigned to 1207 the subtag. A separate subtag should be proposed instead. 1209 The 'Description' field must contain a description of the tag being 1210 registered written or transcribed into the Latin script; it may also 1211 include a description in a non-Latin script. Non-ASCII characters 1212 must be escaped using the syntax described in Section 3.1. The 1213 'Description' field is used for identification purposes and should 1214 not be taken to represent the actual native name of the language or 1215 variation or to be in any particular language. 1217 While the 'Description' field itself is not guaranteed to be stable 1218 and errata corrections may be undertaken from time to time, attempts 1219 to provide translations or transcriptions of entries in the registry 1220 itself will probably be frowned upon by the community or rejected 1221 outright, as changes of this nature may impact the provisions in 1222 Section 3.3. 1224 The Language Subtag Reviewer is responsible for responding to 1225 requests for the registration of subtags through the registration 1226 process and is appointed by the IESG. 1228 When the two week period has passed the Language Subtag Reviewer 1229 either forwards the record to be inserted or modified to 1230 iana@iana.org according to the procedure described in Section 3.2, or 1231 rejects the request because of significant objections raised on the 1232 list or due to problems with constraints in this document (which 1233 should be explicitly cited). The reviewer may also extend the review 1234 period in two week increments to permit further discussion. The 1235 reviewer must indicate on the list whether the registration has been 1236 accepted, rejected, or extended following each two week period. 1238 Note that the reviewer can raise objections on the list if he or she 1239 so desires. The important thing is that the objection must be made 1240 publicly. 1242 The applicant is free to modify a rejected application with 1243 additional information and submit it again; this restarts the two 1244 week comment period. 1246 Decisions made by the reviewer may be appealed to the IESG [RFC 2028] 1247 [9] under the same rules as other IETF decisions [RFC 2026] [8]. 1249 All approved registration forms are available online in the directory 1250 http://www.iana.org/numbers.html under "languages". 1252 Updates or changes to existing records, including previous 1253 registrations, follow the same procedure as new registrations. The 1254 Language Subtag Reviewer decides whether there is consensus to update 1255 the registration following the two week review period; normally 1256 objections by the original registrant will carry extra weight in 1257 forming such a consensus. 1259 Registrations are permanent and stable. Once registered, subtags 1260 will not be removed from the registry and will remain the canonical 1261 method of referring to a specific language or variant. This 1262 provision does not apply to grandfathered tags, which may become 1263 deprecated due to registration of subtags. For example, the tag 1264 "i-navajo" is deprecated in favor of the tag "nv", which consists of 1265 the single primary language subtag 'nv'. 1267 Note: The purpose of the "published description" in the registration 1268 form is intended as an aid to people trying to verify whether a 1269 language is registered or what language or language variation a 1270 particular subtag refers to. In most cases, reference to an 1271 authoritative grammar or dictionary of that language will be useful; 1272 in cases where no such work exists, other well known works describing 1273 that language or in that language may be appropriate. The subtag 1274 reviewer decides what constitutes "good enough" reference material. 1275 This requirement is not intended to exclude particular languages or 1276 dialects due to the size of the speaker population or lack of a 1277 standardized orthography. Minority languages will be considered 1278 equally on their own merits. 1280 3.5 Possibilities for Registration 1282 Possibilities for registration of subtags or information about 1283 subtags include: 1285 o Primary language subtags for languages not listed in ISO 639 that 1286 are not variants of any listed or registered language can be 1287 registered. At the time this document was created there were no 1288 examples of this form of subtag. Before attempting to register a 1289 language subtag, there MUST be an attempt to register the language 1290 with ISO 639. No language subtags will be registered for codes 1291 that exist in ISO 639-1 or ISO 639-2, which are under 1292 consideration by the ISO 639 maintenance or registration 1293 authorities, or which have never been attempted for registration 1294 with those authorities. If ISO 639 has previously rejected a 1295 language for registration, it is reasonable to assume that there 1296 MUST be additional very compelling evidence of need before it will 1297 be registered in the IANA registry (to the extent that it is very 1298 unlikely that any subtags will be registered of this type). 1300 o Dialect or other divisions or variations within a language, its 1301 orthography, writing system, regional or historical usage, 1302 transliteration or other transformation, or distinguishing 1303 variation may be registered as variant subtags. An example is the 1304 'scouse' subtag (the Scouse dialect of English). 1306 o The addition or maintenance of fields (generally of an 1307 informational nature) in Tag or Subtag records as described in 1308 Section 3.1 and subject to the stability provisions in 1309 Section 3.3. This includes descriptions, recommended prefixes, 1310 comments, deprecation of obsolete items, or the addition of script 1311 or extlang information to primary language subtags. 1313 This document leaves the decision on what subtags or changes to 1314 subtags are appropriate (or not) to the registration process 1315 described in Section 3.4. 1317 Note: four character primary language subtags are reserved to allow 1318 for the possibility of alpha4 codes in some future addition to the 1319 ISO 639 family of standards. 1321 ISO 639 defines a maintenance agency for additions to and changes in 1322 the list of languages in ISO 639. This agency is: 1324 International Information Centre for Terminology (Infoterm) 1325 Aichholzgasse 6/12, AT-1120 1326 Wien, Austria 1327 Phone: +43 1 26 75 35 Ext. 312 Fax: +43 1 216 32 72 1329 ISO 639-2 defines a maintenance agency for additions to and changes 1330 in the list of languages in ISO 639-2. This agency is: 1332 Library of Congress 1333 Network Development and MARC Standards Office 1334 Washington, D.C. 20540 USA 1335 Phone: +1 202 707 6237 Fax: +1 202 707 0115 1336 URL: http://www.loc.gov/standards/iso639 1338 The maintenance agency for ISO 3166 (country codes) is: 1340 ISO 3166 Maintenance Agency 1341 c/o International Organization for Standardization 1342 Case postale 56 1343 CH-1211 Geneva 20 Switzerland 1344 Phone: +41 22 749 72 33 Fax: +41 22 749 73 49 1345 URL: http://www.iso.org/iso/en/prods-services/iso3166ma/index.html 1347 The registration authority for ISO 15924 (script codes) is: 1349 Unicode Consortium Box 391476 1350 Mountain View, CA 94039-1476, USA 1351 URL: http://www.unicode.org/iso15924 1353 The Statistics Division of the United Nations Secretariat maintains 1354 the Standard Country or Area Codes for Statistical Use and can be 1355 reached at: 1357 Statistical Services Branch 1358 Statistics Division 1359 United Nations, Room DC2-1620 1360 New York, NY 10017, USA 1362 Fax: +1-212-963-0623 1363 E-mail: statistics@un.org 1364 URL: http://unstats.un.org/unsd/methods/m49/m49alpha.htm 1366 3.6 Extensions and Extensions Namespace 1368 Extension subtags are those introduced by single-letter subtags other 1369 than 'x'. They are reserved for the generation of identifiers which 1370 contain a language component, and are compatible with applications 1371 that understand language tags. For example, they might be used to 1372 define locale identifiers, which are generally based on language. 1374 The structure and form of extensions are defined by this document so 1375 that implementations can be created that are forward compatible with 1376 applications that may be created using single-letter subtags in the 1377 future. In addition, defining a mechanism for maintaining single- 1378 letter subtags will lend to the stability of this document by 1379 reducing the likely need for future revisions or updates. 1381 Allocation of a single-letter subtag shall take the form of an RFC 1382 defining the name, purpose, processes, and procedures for maintaining 1383 the subtags. The maintaining or registering authority, including 1384 name, contact email, discussion list email, and URL location of the 1385 registry must be indicated clearly in the RFC. The RFC MUST specify 1386 or include each of the following: 1388 o The specification MUST reference the specific version or revision 1389 of this document that governs its creation and MUST reference this 1390 section of this document. 1392 o The specification and all subtags defined by the specification 1393 MUST follow the ABNF and other rules for the formation of tags and 1394 subtags as defined in this document. In particular it MUST 1395 specify that case is not significant and that subtags MUST NOT 1396 exceed eight characters in length. 1398 o The specification MUST specify a canonical representation. 1400 o The specification of valid subtags MUST be available over the 1401 Internet and at no cost. 1403 o The specification MUST be in the public domain or available via a 1404 royalty-free license acceptable to the IETF and specified in the 1405 RFC. 1407 o The specification MUST be versioned and each version of the 1408 specification MUST be numbered, dated, and stable. 1410 o The specification MUST be stable. That is, extension subtags, 1411 once defined by a specification, MUST NOT be retracted or change 1412 in meaning in any substantial way. 1414 o The specification MUST include in a separate section the 1415 registration form reproduced in this section (below) to be used in 1416 registering the extension upon publication as an RFC. 1418 o IANA MUST be informed of changes to the contact information and 1419 URL for the specification. 1421 o Modified the latin-script requirement on the 'Description' field 1422 so that "at least one Description field" must contain a Latin 1423 transcription. (A.Phillips) 1425 IANA will maintain a registry of allocated single-letter (singleton) 1426 subtags. This registry will use the record-jar format described by 1427 the ABNF in Section 3.1. Upon publication of an extension as an RFC, 1428 the maintaining authority defined in the RFC must forward this 1429 registration form to iesg@ietf.org, who will forward the request to 1430 iana@iana.org. The maintaining authority of the extension MUST 1431 maintain the accuracy of the record by sending an updated full copy 1432 of the record to iana@iana.org with the subject line "LANGUAGE TAG 1433 EXTENSION UPDATE" whenever content changes. Only the 'Comments', 1434 'Contact_Email', 'Mailing_List', and 'URL' fields may be modified in 1435 these updates. 1437 Failure to maintain this record, the corresponding registry, or meet 1438 other conditions imposed by this section of this document may be 1439 appealed to the IESG [RFC 2028] [9] under the same rules as other 1440 IETF decisions (see [8]) and may result in the authority to maintain 1441 the extension being withdrawn or reassigned by the IESG. 1442 %% 1443 Identifier: 1444 Description: 1445 Comments: 1446 Added: 1447 RFC: 1448 Authority: 1449 Contact_Email: 1450 Mailing_List: 1451 URL: 1452 %% 1454 Figure 6: Format of Records in the Language Tag Extensions Registry 1456 'Identifier' contains the single letter subtag (singleton) assigned 1457 to the extension. The Internet-Draft submitted to define the 1458 extension should specific which letter to use, although the IESG may 1459 change the assignment when approving the RFC. 1461 'Description' contains the name and description of the extension. 1463 'Comments' is an optional field and may contain a broader description 1464 of the extension. 1466 'Added' contains the date the RFC was published in the "full-date" 1467 format specified in RFC 3339 [14]. For example: 2004-06-28 1468 represents June 28, 2004, in the Gregorian calendar. 1470 'RFC' contains the RFC number assigned to the extension. 1472 'Authority' contains the name of the maintaining authority for the 1473 extension. 1475 'Contact_Email' contains the email address used to contact the 1476 maintaining authority. 1478 'Mailing_List' contains the URL or subscription email address of the 1479 mailing list used by the maintaining authority. 1481 'URL' contains the URL of the registry for this extension. 1483 The determination of whether an Internet-Draft meets the above 1484 conditions and the decision to grant or withhold such authority rests 1485 solely with the IESG, and is subject to the normal review and appeals 1486 process associated with the RFC process. 1488 Extension authors are strongly cautioned that many (including most 1489 well-formed) processors will be unaware of any special relationships 1490 or meaning inherent in the order of extension subtags. Extension 1491 authors SHOULD avoid subtag relationships or canonicalization 1492 mechanisms that interfere with matching or with length restrictions 1493 that may exist in common protocols where the extension is used. In 1494 particular, applications may truncate the subtags in doing matching 1495 or in fitting into limited lengths, so it is RECOMMENDED that the 1496 most significant information be in the most significant (left-most) 1497 subtags, and that the specification gracefully handle truncated 1498 subtags. 1500 When a language tag is to be used in a specific, known, protocol, it 1501 is RECOMMENDED that that the language tag not contain extensions not 1502 supported by that protocol. In addition, it should be noted that 1503 some protocols may impose upper limits on the length of the strings 1504 used to store or transport the language tag. 1506 3.7 Conversion of the RFC 3066 Language Tag Registry 1508 Upon publication of this document as a BCP, the existing IANA 1509 language tag registry must be converted into the new subtag registry. 1510 This section defines the process for performing this conversion. 1512 The impact on the IANA maintainers of the registry of this conversion 1513 will be a small increase in the frequency of new entries. The 1514 initial set of records represents no impact on IANA, since the work 1515 to create it will be performed externally (as defined in this 1516 section). Future work will be limited to inserting or replacing 1517 whole records preformatted for IANA by the Language Subtag Reviewer. 1519 When this document is published, an email will be sent by the 1520 chair(s) of the LTRU working group to the LTRU and ietf-languages 1521 mail lists advising of the impending conversion of the registry. In 1522 that notice, the chair(s) will provide a URL whose referred content 1523 is the proposed IANA Language Subtag Registry following conversion. 1524 There will be a Last Call period of not less than four weeks for 1525 comments and corrections to be discussed on the 1526 ietf-languages@iana.org mail list. Changes as a result of comments 1527 will not restart the Last Call period. At the end of the period, the 1528 chair(s) will forward the URL to IANA, which will post the new 1529 registry on-line. 1531 Tags that are currently deprecated will be maintained as 1532 grandfathered entries. The record for the grandfathered entry will 1533 contain a 'Deprecated' field with the most appropriate date that can 1534 be determined for when the record was deprecated. The 'Comments' 1535 field will contain the reason for the deprecation. The 'Canonical' 1536 field will contain the tag that replaces the value. For example, the 1537 tag "art-lojban" is deprecated and will be placed in the 1538 grandfathered section. It's 'Deprecated' field will contain the 1539 deprecation date and 'Canonical' field the value "jbo". 1541 Tags that are not deprecated that consist entirely of subtags that 1542 are valid under this document and which have the correct form and 1543 format for tags defined by this document are superseded by this 1544 document. Such tags are placed in records of type 'redundant' in the 1545 registry. For example, "zh-Hant" is now defined by this document. 1547 Tags that are not deprecated and which contain subtags which are 1548 consistent with registration under the guidelines in this document 1549 will have a new subtag registration created for each eligible subtag. 1550 If all of the subtags in the original tag are fully defined by the 1551 resulting registrations or by this document, then the original tag is 1552 superseded by this document. Such tags are placed in the 'redundant' 1553 section of the registry. For example, "en-boont" will result in a 1554 new subtag 'boont' and the RFC 3066 registered tag "en-boont" placed 1555 in the redundant section of the registry. 1557 Tags that contain one or more subtags that do not match the valid 1558 registration pattern and which are not otherwise defined by this 1559 document will have records of type 'grandfathered' created in the 1560 registry. 1562 There will be a reasonable period in which the community may comment 1563 on the proposed list entries, which SHALL be no less than four weeks 1564 in length. At the completion of this period, the chair(s) will 1565 notify iana@iana.org and the ltru and ietf-languages mail lists that 1566 the task is complete and forward the necessary materials to IANA for 1567 publication. 1569 Registrations that are in process under the rules defined in RFC 3066 1570 MAY be completed under the former rules, at the discretion of the 1571 language tag reviewer. Any new registrations submitted after the 1572 request for conversion of the registry MUST be rejected. 1574 All existing RFC 3066 language tag registrations will be maintained 1575 in perpetuity. 1577 Users of tags that are grandfathered should consider registering 1578 appropriate subtags in the IANA subtag registry (but are not required 1579 to). 1581 Where two subtags have the same meaning, the priority of which to 1582 make canonical SHALL be the following: 1584 o As of the date of acceptance of this document as a BCP, if a code 1585 exists in the associated ISO standard and it is not deprecated or 1586 withdrawn as of that date, then it has priority. 1588 o Otherwise, the earlier-registered tag in the associated ISO 1589 standard has priority. 1591 UN numeric codes assigned to 'macro-geographical (continental)' or 1592 sub-regions not associated with an assigned ISO 3166 alpha-2 code are 1593 defined in the IANA registry and are valid for use in language tags. 1594 These codes MUST be added to the initial version of the registry. 1595 The UN numeric codes for 'economic groupings' or 'other groupings', 1596 and the alphanumeric codes in Appendix X of the UN document MUST NOT 1597 be added to the registry. 1599 When creating records for ISO 639, ISO 15924, ISO3166, and UN M.49 1600 codes, the following criteria SHALL be applied to the inclusion, 1601 canonical mapping, and deprecation of codes: 1603 For each standard, the date of the standard referenced in RFC 1766 is 1604 selected as the starting date. Codes that were valid on that date in 1605 the selected standard are added to the registry. Codes that were 1606 previously assigned by were vacated or withdrawn before that date are 1607 not added to the registry. For each successive change to the 1608 standard, any additional assignments are added to the registry. 1609 Values that are withdrawn are marked as deprecated, but not removed. 1610 Changes in meaning or assignment of a subtag are permitted during 1611 this process (cf. 'CS'). This continues up to the date that this 1612 document was adopted. The resulting set of records is added to the 1613 registry. Future changes or additions to this portion of the 1614 registry are governed by the provisions of this document. 1616 4. Formation and Processing of Language Tags 1618 This section addresses how to use the registry with the language tag 1619 format to choose, form and process language tags. 1621 4.1 Choice of Language Tag 1623 One may occasionally be faced with several possible tags for the same 1624 body of text. 1626 Interoperability is best served when all users use the same language 1627 tag in order to represent the same language. If an application has 1628 requirements that make the rules here inapplicable, then that 1629 application risks damaging interoperability. It is strongly 1630 RECOMMENDED that users not define their own rules for language tag 1631 choice. 1633 Of particular note, many applications can benefit from the use of 1634 script subtags in language tags, as long as the use is consistent for 1635 a given context. Script subtags were not formally defined in RFC 1636 3066 and their use may affect matching and subtag identification by 1637 implementations of RFC 3066, as these subtags appear between the 1638 primary language and region subtags. For example, if a user requests 1639 content in an implementation of Section 2.5 of RFC 3066 [23] using 1640 the language range "en-US", content labeled "en-Latn-US" will not 1641 match the request. Therefore it is important to know when script 1642 subtags will customarily be used and when they should not be used. 1643 In the registry, the Suppress-Script field helps ensure greater 1644 compatibility between the language tags generated according to the 1645 rules in this document and language tags and tag processors or 1646 consumers based on RFC 3066 by defining when users should generally 1647 not include a script subtag with a particular primary language 1648 subtag. 1650 Extended language subtags (type 'extlang' in the registry, see 1651 Section 3.1) also appear between the primary language and region 1652 subtags and are reserved for future standardization. Applications 1653 may benefit from their judicious use in forming language tags in the 1654 future and similar recommendations are expected to apply to their use 1655 as apply to script subtags. 1657 Standards, protocols and applications that reference this document 1658 normatively but apply different rules to the ones given in this 1659 section MUST specify how the procedure varies from the one given 1660 here. 1662 The choice of subtags used to form a language tag should be guided by 1663 the following rules: 1665 1. Use as precise a tag as possible, but no more specific than is 1666 justified. Avoid using subtags that are not important for 1667 distinguishing content in an application. 1669 * For example, 'de' might suffice for tagging an email written 1670 in German, while "de-CH-1996" is probably unnecessarily 1671 precise for such a task. 1673 2. The script subtag SHOULD NOT be used to form language tags unless 1674 the script adds some distinguishing information to the tag. The 1675 field 'Suppress-Script' in the primary language record in the 1676 registry indicates which script subtags do not add distinguishing 1677 information for most applications. 1679 * For example, the subtag 'Latn' should not be used with the 1680 primary language 'en' because nearly all English documents are 1681 written in the Latin script and it adds no distinguishing 1682 information. However, if a document were written in English 1683 mixing Latin script with another script such as Braille 1684 ('Brai'), then it may be appropriate to choose to indicate 1685 both scripts to aid in content selection, such as the 1686 application of a stylesheet. 1688 3. If a subtag has a 'Canonical' field in its registry entry, the 1689 canonical subtag SHOULD be used to form the language tag in 1690 preference to any of its aliases. 1692 * For example, use 'he' for Hebrew in preference to 'iw'. 1694 4. The 'und' (Undetermined) primary language subtag SHOULD NOT be 1695 used to label content, even if the language is unknown. Omitting 1696 the language tag altogether is preferred to using a tag with a 1697 primary language subtag of 'und'. The 'und' subtag may be useful 1698 for protocols that require a language tag to be provided. The 1699 'und' subtag may also be useful when matching language tags in 1700 certain situations. 1702 5. The 'mul' (Multiple) primary language subtag SHOULD NOT be used 1703 whenever the protocol allows the separate tags for multiple 1704 languages, as is the case for the Content-Language header in 1705 HTTP. The 'mul' subtag conveys little useful information: 1706 content in multiple languages should individually tag the 1707 languages where they appear or otherwise indicate the actual 1708 language in preference to the 'mul' subtag. 1710 6. The same variant subtag SHOULD NOT be used more than once within 1711 a language tag. 1713 * For example, do not use "en-GB-scouse-scouse". 1715 To ensure consistent backward compatibility, this document contains 1716 several provisions to account for potential instability in the 1717 standards used to define the subtags that make up language tags. 1718 These provisions mean that no language tag created under the rules in 1719 this document will become obsolete. In addition, tags that are in 1720 canonical form will always be in canonical form. 1722 4.2 Meaning of the Language Tag 1724 The language tag always defines a language as spoken (or written, 1725 signed or otherwise signaled) by human beings for communication of 1726 information to other human beings. Computer languages such as 1727 programming languages are explicitly excluded. 1729 If a language tag B contains language tag A as a prefix, then B is 1730 typically "narrower" or "more specific" than A. For example, "zh- 1731 Hant-TW" is more specific than "zh-Hant". 1733 This relationship is not guaranteed in all cases: specifically, 1734 languages that begin with the same sequence of subtags are NOT 1735 guaranteed to be mutually intelligible, although they may be. For 1736 example, the tag "az" shares a prefix with both "az-Latn" 1737 (Azerbaijani written using the Latin script) and "az-Cyrl" 1738 (Azerbaijani written using the Cyrillic script). A person fluent in 1739 one script may not be able to read the other, even though the text 1740 might be identical. Content tagged as "az" most probably is written 1741 in just one script and thus might not be intelligible to a reader 1742 familiar with the other script. 1744 The relationship between the tag and the information it relates to is 1745 defined by the standard describing the context in which it appears. 1746 Accordingly, this section can only give possible examples of its 1747 usage. 1749 o For a single information object, the associated language tags 1750 might be interpreted as the set of languages that is required for 1751 a complete comprehension of the complete object. Example: Plain 1752 text documents. 1754 o For an aggregation of information objects, the associated language 1755 tags could be taken as the set of languages used inside components 1756 of that aggregation. Examples: Document stores and libraries. 1758 o For information objects whose purpose is to provide alternatives, 1759 the associated language tags could be regarded as a hint that the 1760 content is provided in several languages, and that one has to 1761 inspect each of the alternatives in order to find its language or 1762 languages. In this case, the presence of multiple tags might not 1763 mean that one needs to be multi-lingual to get complete 1764 understanding of the document. Example: MIME multipart/ 1765 alternative. 1767 o In markup languages, such as HTML and XML, language information 1768 can be added to each part of the document identified by the markup 1769 structure (including the whole document itself). For example, one 1770 could write C'est la vie. inside a 1771 Norwegian document; the Norwegian-speaking user could then access 1772 a French-Norwegian dictionary to find out what the marked section 1773 meant. If the user were listening to that document through a 1774 speech synthesis interface, this formation could be used to signal 1775 the synthesizer to appropriately apply French text-to-speech 1776 pronunciation rules to that span of text, instead of applying the 1777 inappropriate Norwegian rules. 1779 4.3 Canonicalization of Language Tags 1781 Since a particular language tag may be used in many processes, 1782 language tags SHOULD always be created or generated in a canonical 1783 form. 1785 A language tag is in canonical form when: 1787 1. The tag is well-formed according the rules in Section 2.1 and 1788 Section 2.2. 1790 2. None of the subtags in the language tag has a Canonical-Value 1791 mapping in the IANA registry (see Section 3.1). Subtags with a 1792 Canonical-Value mapping MUST be replaced with their mapping in 1793 order to canonicalize the tag. 1795 3. If more than one extension subtag sequence exists, the extension 1796 sequences are ordered into case-insensitive ASCII order by 1797 singleton subtag. 1799 Example: The language tag "en-A-aaa-B-ccc-bbb-x-xyz" is in canonical 1800 form, while "en-B-ccc-bbb-A-aaa-X-xyz" is well-formed but not in 1801 canonical form. 1803 Example: The language tag "en-NH" (English as used in the New 1804 Hebrides) is not canonical because the 'NH' subtag has a canonical 1805 mapping to 'VU' (Vanuatu). 1807 Canonicalization of language tags does not imply anything about the 1808 use of upper or lowercase letters when processing or comparing 1809 subtags (and as described in Section 2.1). All comparisons MUST be 1810 performed in a case-insensitive manner. 1812 When performing canonicalization of language tags, processors MAY 1813 optionally regularize the case of the subtags, following the case 1814 used in the registry. Note that this corresponds to the following 1815 casing rules: uppercase all non-initial two-letter subtags; titlecase 1816 all non-initial four-letter subtags; lowercase everything else. 1818 Note: Case folding of ASCII letters in certain locales, unless 1819 carefully handled, may produce non-ASCII character values. The 1820 Unicode Character Database file "SpecialCasing.txt" defines the 1821 specific cases that are known to cause problems with this. In 1822 particular, the letter 'i' (U+0069) in Turkish and Azerbaijani is 1823 uppercased to U+0130 (LATIN CAPITAL LETTER I WITH DOT ABOVE). 1824 Implementers should specify a locale-neutral casing operation to 1825 ensure that case folding of subtags does not produce this value, 1826 which is illegal in language tags. For example, if one were to 1827 uppercase the region subtag 'in' using Turkish locale rules, the 1828 sequence U+0130 U+004E would result instead of the expected 'IN'. 1830 Note: if the field 'Deprecated' appears in a registry record without 1831 an accompanying 'Canonical' field, then that tag or subtag is 1832 deprecated without a replacement. Validating processors SHOULD NOT 1833 generate tags that include these values, although the values are 1834 canonical when they appear in a language tag. 1836 An extension MUST define any relationships that may exist between the 1837 various subtags in the extension and thus MAY define an alternate 1838 canonicalization scheme for the extension's subtags. Extensions MAY 1839 define how the order of the extension's subtags are interpreted. For 1840 example, an extension could define that its subtags are in canonical 1841 order when the subtags are placed into ASCII order: that is, "en-a- 1842 aaa-bbb-ccc" instead of "en-a-ccc-bbb-aaa". Another extension might 1843 define that the order of the subtags influences their semantic 1844 meaning (so that "en-b-ccc-bbb-aaa" has a different value from "en-b- 1845 aaa-bbb-ccc"). However, extension specifications SHOULD be designed 1846 so that they are tolerant of the typical processes described in 1847 Section 3.6. 1849 4.4 Considerations for Private Use Subtags 1851 Private-use subtags require private agreement between the parties 1852 that intend to use or exchange language tags that use them and great 1853 caution should be used in employing them in content or protocols 1854 intended for general use. Private-use subtags are simply useless for 1855 information exchange without prior arrangement. 1857 The value and semantic meaning of private-use tags and of the subtags 1858 used within such a language tag are not defined by this document. 1860 The use of subtags defined in the IANA registry as having a specific 1861 private use meaning convey more information that a purely private use 1862 tag prefixed by the singleton subtag 'x'. For applications this 1863 additional information may be useful. 1865 For example, the region subtags 'AA', 'ZZ' and in the ranges 1866 'QM'-'QZ' and 'XA'-'XZ' (derived from ISO 3166 private use codes) may 1867 be used to form a language tag. A tag such as "zh-Hans-XQ" conveys a 1868 great deal of public, interchangeable information about the language 1869 material (that it is Chinese in the simplified Chinese script and is 1870 suitable for some geographic region 'XQ'). While the precise 1871 geographic region is not known outside of private agreement, the tag 1872 conveys far more information than an opaque tag such as "x-someLang", 1873 which contains no information about the language subtag or script 1874 subtag outside of the private agreement. 1876 However, in some cases content tagged with private use subtags may 1877 interact with other systems in a different and possibly unsuitable 1878 manner compared to tags that use opaque, privately defined subtags, 1879 so the choice of the best approach may depend on the particular 1880 domain in question. 1882 5. IANA Considerations 1884 This section deals with the processes and requirements necessary for 1885 IANA to undertake to maintain the rsubtag and extension registries as 1886 defined by this document and in accordance with the requirements of 1887 RFC 2434 [11]. 1889 The impact on the IANA maintainers of the two registries defined by 1890 this document will be a small increase in the frequency of new 1891 entries or updates. 1893 Upon adoption of this document, the process described in Section 3.7 1894 will be used to generate the initial Language Subtag Registry. The 1895 initial set of records represents no impact on IANA, since the work 1896 to create it will be performed externally (as defined in that 1897 section). The new registry will be listed under "Language Tags" at 1898 . The existing directory of 1899 registration forms and RFC 3066 registrations will be relabeled as 1900 "Language Tags (Obsolete)" and maintained (but not added to or 1901 modified). 1903 Future work on the Language Subtag Registry will be limited to 1904 inserting or replacing whole records preformatted for IANA by the 1905 Language Subtag Reviewer as described in Section 3.2 of this 1906 document. Each record will be sent to iana@iana.org with a subject 1907 line indicating whether the enclosed record is an insertion (of a new 1908 record) or a replacment of an existing record which has a Type and 1909 Subtag (or Tag) field that exactly matches the record sent. Records 1910 cannot be deleted from the registry. 1912 The Language Tag Extensions registry will also be generated and sent 1913 to IANA as described in Section 3.6. This registry may contain at 1914 most 35 records and thus changes to this registry are expected to be 1915 very infrequent. 1917 Future work by IANA on the Language Tag Extensions Registry is 1918 limited to two cases. First, the IESG may request that new records 1919 be inserted into this registry from time to time. These requests 1920 will include the record to insert in the exact format described in 1921 Section 3.6. In addition, there may be occasional requests from the 1922 maintaining authority for a specific extension to update the contact 1923 information or URLs in the record. These requests MUST include the 1924 complete, updated record. IANA is not responsible for validating the 1925 information provided, only that it is properly formatted. It should 1926 reasonably be seen to come from the maintaining authority named in 1927 the record present in the registry. 1929 6. Security Considerations 1931 The only security issue that has been raised with language tags since 1932 the publication of RFC 1766 [21], which stated that "Security issues 1933 are believed to be irrelevant to this memo", is a concern with 1934 language identifiers used in content negotiation - that they may be 1935 used to infer the nationality of the sender, and thus identify 1936 potential targets for surveillance. 1938 This is a special case of the general problem that anything sent is 1939 visible to the receiving party and possibly to third parties as well. 1940 It is useful to be aware that such concerns can exist in some cases. 1942 The evaluation of the exact magnitude of the threat, and any possible 1943 countermeasures, is left to each application protocol (see BCP 72, 1944 RFC 3552 [15] for best current practice guidance on security threats 1945 and defenses). 1947 Although the specification of valid subtags for an extension MUST be 1948 available over the Internet, implementations SHOULD NOT mechanically 1949 depend on it being always accessible, to prevent denial-of-service 1950 attacks. 1952 7. Character Set Considerations 1954 The syntax in this document requires that language tags use only the 1955 characters A-Z, a-z, 0-9, and HYPHEN-MINUS, which are present in most 1956 character sets, so the composition of language tags should not have 1957 any character set issues. 1959 Rendering of characters based on the content of a language tag is not 1960 addressed in this memo. Historically, some languages have relied on 1961 the use of specific character sets or other information in order to 1962 infer how a specific character should be rendered (notably this 1963 applies to language and culture specific variations of Han ideographs 1964 as used in Japanese, Chinese, and Korean). When language tags are 1965 applied to spans of text, rendering engines may use that information 1966 in deciding which font to use in the absence of other information, 1967 particularly where languages with distinct writing traditions use the 1968 same characters. 1970 8. Changes from RFC 3066 1972 The main goals for this revision of language tags were the following: 1974 *Compatibility.* All valid RFC 3066 language tags (including those 1975 in the IANA registry) remain valid in this specification. Thus 1976 there is complete backward compatibility of this specification with 1977 existing content. In addition, this document defines language tags 1978 in such as way as to ensure future compatibility, and processors 1979 based solely on the RFC 3066 ABNF (such as those described in XML 1980 Schema version 1.0 [19]) will be able to process tags described by 1981 this document. 1983 *Stability.* Because of the changes in underlying ISO standards, a 1984 valid RFC 3066 language tag may become invalid (or have its meaning 1985 change) at a later date. With so much of the world's computing 1986 infrastructure dependent on language tags, this is simply 1987 unacceptable: it invalidates content that may have an extensive 1988 shelf-life. In this specification, once a language tag is valid, it 1989 remains valid forever. Previously, there was no way to determine 1990 when two tags were equivalent. This specification provides a stable 1991 mechanism for doing so, through the use of canonical forms. These 1992 are also stable, so that implementations can depend on the use of 1993 canonical forms to assess equivalency. 1995 *Validity.* The structure of language tags defined by this document 1996 makes it possible to determine if a particular tag is well-formed 1997 without regard for the actual content or "meaning" of the tag as a 1998 whole. This is important because the registry and underlying 1999 standards change over time. In addition, it must be possible to 2000 determine if a tag is valid (or not) for a given point in time in 2001 order to provide reproducible, testable results. This process must 2002 not be error-prone; otherwise even intelligent people will generate 2003 implementations that give different results. This specification 2004 provides for that by having a single data file, with specific 2005 versioning information, so that the validity of language tags at any 2006 point in time can be precisely determined (instead of interpolating 2007 values from many separate sources). 2009 *Extensibility.* It is important to be able to differentiate between 2010 written forms of language -- for many implementations this is more 2011 important than distinguishing between spoken variants of a language. 2012 Languages are written in a wide variety of different scripts, so this 2013 document provides for the generative use of ISO 15924 script codes. 2014 Like the generative use of ISO language and country codes in RFC 2015 3066, this allows combinations to be produced without resorting to 2016 the registration process. The addition of UN codes provides for the 2017 generation of language tags with regional scope, which is also 2018 required for information technology. 2020 The recast of the registry from containing whole language tags to 2021 subtags is a key part of this. An important feature of RFC 3066 was 2022 that it allowed generative use of subtags. This allows people to 2023 meaningfully use generated tags, without the delays in registering 2024 whole tags, and the burden on the registry of having to supply all of 2025 the combinations that people may find useful. 2027 Because of the widespread use of language tags, it is potentially 2028 disruptive to have periodic revisions of the core specification, 2029 despite demonstrated need. The extension mechanism provides for a 2030 way for independent RFCs to define extensions to language tags. 2031 These extensions have a very constrained, well-defined structure to 2032 prevent extensions from interfering with implementations of language 2033 tags defined in this document. The document also anticipates 2034 features of ISO 639-3 with the addition of the extended language 2035 subtags, as well as the possibility of other ISO 639 parts becoming 2036 useful for the formation of language tags in the future. The use and 2037 definition of private use tags has also been modified, to allow 2038 people to move as much information as possible out of private use 2039 tags, and into the regular structure. The goal is to dramatically 2040 reduce the need to produce a revision of this document in the future. 2042 The specific changes in this document to meet these goals are: 2044 o Defines the ABNF and rules for subtags so that the category of all 2045 subtags can be determined without reference to the registry. 2047 o Adds the concept of well-formed vs. validating processors, 2048 defining the rules by which an implementation can claim to be one 2049 or the other. 2051 o Replaces the IANA language tag registry with a language subtag 2052 registry that provides a complete list of valid subtags in the 2053 IANA registry. This allows for robust implementation and ease of 2054 maintenance. The language subtag registry becomes the canonical 2055 source for forming language tags. 2057 o Provides a process that guarantees stability of language tags, by 2058 handling reuse of values by ISO 639, ISO 15924, and ISO 3166 in 2059 the event that they register a previously used value for a new 2060 purpose. 2062 o Allows ISO 15924 script code subtags and allows them to be used 2063 generatively. Defines a method for indicating in the registry 2064 when script subtags are necessary for a given language tag. 2066 o Adds the concept of a variant subtag and allows variants to be 2067 used generatively. 2069 o Adds the ability to use a class of UN M.49 tags for supra- 2070 national regions and to resolve conflicts in the assignment of ISO 2071 3166 codes. 2073 o Defines the private-use tags in ISO 639, ISO 15924, and ISO 3166 2074 as the mechanism for creating private-use language, script, and 2075 region subtags respectively. 2077 o Adds a well-defined extension mechanism. 2079 o Defines an extended language subtag, possibly for use with certain 2080 anticipated features of ISO 639-3. 2082 Ed Note: The following items are provided for the convenience of 2083 reviewers and will be removed from the final document. 2085 Changes between draft-ietf-ltru-registry-01 and this version are: 2087 o Minor updates to the changes section (the text just above) to 2088 reflect various updates in the WG drafts (A.Phillips) 2090 o Minor change to the section on the extensions registry (because 2091 there can be 35, not 25, entries maximum. (D.Ewell) 2093 o Changed "SHOULD NOT permit a subtag to be divided" to MUST NOT. 2094 (#944) (R.Presuhn) 2096 o Added text to Section 3.1 and Section 4.1 describing the rationale 2097 for Suppress-Script. Both sentences are slight rewordings of this 2098 text suggested in the email thread: "This field helps ensure 2099 greater compatibility between the language tags generated 2100 according to the rules in this document and language tags and tag 2101 processors or consumers based on RFC 3066." (#954) (F.Ellermann, 2102 A.Phillips) 2104 o Added text about case folding during canonicalization. This also 2105 includes rules in Section 3.2 for casing of registry entries, as 2106 well the insertion of the text permitting case normalization in 2107 Section 4.3 and the warning about locale-specific casing 2108 operations in the same section. (#985) (F.Ellermann, J.Cowan, 2109 A.Phillips) 2111 o Fixed the reference to Canonical-Value in Section 4.3. 2112 (A.Phillips) 2114 o In Section 3.4, changed the reference from the subtag 'nv' to the 2115 tag "nv" to be consistent with the wording in Section 3.1. (part 2116 of #954) (D.Ewell) 2118 o Added missing word 'that' in Section 3.6 (A.Phillips) 2120 9. References 2122 9.1 Normative References 2124 [1] International Organization for Standardization, "ISO 639- 2125 1:2002, Codes for the representation of names of languages -- 2126 Part 1: Alpha-2 code", ISO Standard 639, 2002. 2128 [2] International Organization for Standardization, "ISO 639-2:1998 2129 - Codes for the representation of names of languages -- Part 2: 2130 Alpha-3 code - edition 1", August 1988. 2132 [3] ISO TC46/WG3, "ISO 15924:2003 (E/F) - Codes for the 2133 representation of names of scripts", January 2004. 2135 [4] International Organization for Standardization, "Codes for the 2136 representation of names of countries, 3rd edition", 2137 ISO Standard 3166, August 1988. 2139 [5] Statistical Division, United Nations, "Standard Country or Area 2140 Codes for Statistical Use", UN Standard Country or Area Codes 2141 for Statistical Use, Revision 4 (United Nations publication, 2142 Sales No. 98.XVII.9, June 1999. 2144 [6] International Organization for Standardization, "ISO/IEC 10646- 2145 1:2000. Information technology -- Universal Multiple-Octet 2146 Coded Character Set (UCS) -- Part 1: Architecture and Basic 2147 Multilingual Plane and ISO/IEC 10646-2:2001. Information 2148 technology -- Universal Multiple-Octet Coded Character Set 2149 (UCS) -- Part 2: Supplementary Planes, as, from time to time, 2150 amended, replaced by a new edition or expanded by the addition 2151 of new parts", 2000. 2153 [7] Crocker, D. and P. Overell, "Augmented BNF for Syntax 2154 Specifications: ABNF", draft-crocker-abnf-rfc2234bis-00 (work 2155 in progress), March 2005. 2157 [8] Bradner, S., "The Internet Standards Process -- Revision 3", 2158 BCP 9, RFC 2026, October 1996. 2160 [9] Hovey, R. and S. Bradner, "The Organizations Involved in the 2161 IETF Standards Process", BCP 11, RFC 2028, October 1996. 2163 [10] Bradner, S., "Key words for use in RFCs to Indicate Requirement 2164 Levels", BCP 14, RFC 2119, March 1997. 2166 [11] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA 2167 Considerations Section in RFCs", BCP 26, RFC 2434, 2168 October 1998. 2170 [12] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO 10646", 2171 RFC 2781, February 2000. 2173 [13] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of 2174 Understanding Concerning the Technical Work of the Internet 2175 Assigned Numbers Authority", RFC 2860, June 2000. 2177 [14] Klyne, G. and C. Newman, "Date and Time on the Internet: 2178 Timestamps", RFC 3339, July 2002. 2180 [15] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on 2181 Security Considerations", BCP 72, RFC 3552, July 2003. 2183 9.2 Informative References 2185 [16] ISO 639 Joint Advisory Committee, "ISO 639 Joint Advisory 2186 Committee: Working principles for ISO 639 maintenance", 2187 March 2000, 2188 . 2190 [17] Raymond, E., "The Art of Unix Programming", 2003. 2192 [18] Bray (et al), T., "Extensible Markup Language (XML) 1.0", 2193 02 2004. 2195 [19] Biron, P., Ed. and A. Malhotra, Ed., "XML Schema Part 2: 2196 Datatypes Second Edition", 10 2004, < 2197 http://www.w3.org/TR/xmlschema-2/>. 2199 [20] Unicode Consortium, "The Unicode Consortium. The Unicode 2200 Standard, Version 4.1.0, defined by: The Unicode Standard, 2201 Version 4.0 (Boston, MA, Addison-Wesley, 2003. ISBN 0-321- 2202 18578-1), as amended by Unicode 4.0.1 2203 (http://www.unicode.org/versions/Unicode4.0.1) and by Unicode 2204 4.1.0 (http://www.unicode.org/versions/Unicode4.1.0).", 2205 March 2005. 2207 [21] Alvestrand, H., "Tags for the Identification of Languages", 2208 RFC 1766, March 1995. 2210 [22] Freed, N. and K. Moore, "MIME Parameter Value and Encoded Word 2211 Extensions: Character Sets, Languages, and Continuations", 2212 RFC 2231, November 1997. 2214 [23] Alvestrand, H., "Tags for the Identification of Languages", 2215 BCP 47, RFC 3066, January 2001. 2217 Authors' Addresses 2219 Addison Phillips (editor) 2220 Quest Software 2222 Email: addison.phillips@quest.com 2224 Mark Davis (editor) 2225 IBM 2227 Email: mark.davis@us.ibm.com 2229 Appendix A. Acknowledgements 2231 Any list of contributors is bound to be incomplete; please regard the 2232 following as only a selection from the group of people who have 2233 contributed to make this document what it is today. 2235 The contributors to RFC 3066 and RFC 1766, the precursors of this 2236 document, made enormous contributions directly or indirectly to this 2237 document and are generally responsible for the success of language 2238 tags. 2240 The following people (in alphabetical order) contributed to this 2241 document or to RFCs 1766 and 3066: 2243 Glenn Adams, Harald Tveit Alvestrand, Tim Berners-Lee, Marc Blanchet, 2244 Nathaniel Borenstein, Eric Brunner, Sean M. Burke, M.T. Carrasco 2245 Benitez, Jeremy Carroll, John Clews, Jim Conklin, Peter Constable, 2246 John Cowan, Mark Crispin, Dave Crocker, Martin Duerst, Frank 2247 Ellerman, Michael Everson, Doug Ewell, Ned Freed, Tim Goodwin, Dirk- 2248 Willem van Gulik, Marion Gunn, Joel Halpren, Elliotte Rusty Harold, 2249 Paul Hoffman, Scott Hollenbeck, Richard Ishida, Olle Jarnefors, Kent 2250 Karlsson, John Klensin, Alain LaBonte, Eric Mader, Ira McDonald, 2251 Keith Moore, Chris Newman, Masataka Ohta, Randy Presuhn, George 2252 Rhoten, Markus Scherer, Keld Jorn Simonsen, Thierry Sourbier, Otto 2253 Stolz, Tex Texin, Andrea Vine, Rhys Weatherley, Misha Wolf, Francois 2254 Yergeau and many, many others. 2256 Very special thanks must go to Harald Tveit Alvestrand, who 2257 originated RFCs 1766 and 3066, and without whom this document would 2258 not have been possible. Special thanks must go to Michael Everson, 2259 who has served as language tag reviewer for almost the complete 2260 period since the publication of RFC 1766. Special thanks to Doug 2261 Ewell, for his production of the first complete subtag registry, and 2262 his work in producing a test parser for verifying language tags. 2264 Appendix B. Examples of Language Tags (Informative) 2266 Simple language subtag: 2268 de (German) 2270 fr (French) 2272 ja (Japanese) 2274 i-enochian (example of a grandfathered tag) 2276 Language subtag plus Script subtag: 2278 zh-Hant (Chinese written using the Traditional Chinese script) 2280 zh-Hans (Chinese written using the Simplified Chinese script) 2282 sr-Cyrl (Serbian written using the Cyrillic script) 2284 sr-Latn (Serbian written using the Latin script) 2286 Language-Script-Region: 2288 zh-Hans-CN (Chinese written using the Simlified script as used in 2289 mainland China) 2291 sr-Latn-CS (Serbian written using the Latin script as used in 2292 Serbia and Montenegro) 2294 Language-Variant: 2296 en-boont (Boontling dialect of English) 2298 en-scouse (Scouse dialect of English) 2300 Language-Region-Variant: 2302 en-GB-scouse (Scouse dialect of English as used in the UK) 2304 Language-Script-Region-Variant: 2306 sl-Latn-IT-nedis (Nadiza dialect of Slovenian written using the 2307 Latin script as used in Italy. Note that this tag is not 2308 recommended because subtag 'sl' has a Suppress-Script value of 2309 'Latn') 2311 Language-Region: 2313 de-DE (German for Germany) 2315 en-US (English as used in the United States) 2317 es-419 (Spanish for Latin America and Caribbean region using the 2318 UN region code) 2320 Private-use subtags: 2322 de-CH-x-phonebk 2324 az-Arab-x-AZE-derbend 2326 Extended language subtags (examples ONLY: extended languages must be 2327 defined by revision or update to this document): 2329 zh-min 2331 zh-min-nan-Hant-CN 2333 Private-use registry values: 2335 x-whatever (private use using the singleton 'x') 2337 qaa-Qaaa-QM-x-southern (all private tags) 2339 de-Qaaa (German, with a private script) 2341 sr-Latn-QM (Serbian, Latin-script, private region) 2343 sr-Qaaa-CS (Serbian, private script, for Serbia and Montenegro) 2345 Tags that use extensions (examples ONLY: extensions must be defined 2346 by revision or update to this document or by RFC): 2348 en-US-u-islamCal 2350 zh-CN-a-myExt-x-private 2352 en-a-myExt-b-another 2354 Some Invalid Tags: 2356 de-419-DE (two region tags) 2357 a-DE (use of a single character subtag in primary position; note 2358 that there are a few grandfathered tags that start with "i-" that 2359 are valid) 2361 ar-a-aaa-b-bbb-a-ccc (two extensions with same single letter 2362 prefix) 2364 Appendix C. Example Registry 2366 Example Registry 2368 File-Date: 2005-04-18 2369 %% 2370 Type: language 2371 Subtag: aa 2372 Description: Afar 2373 Added: 2004-07-06 2374 %% 2375 Type: language 2376 Subtag: ab 2377 Description: Abkhazian 2378 Added: 2004-07-06 2379 %% 2380 Type: language 2381 Subtag: ae 2382 Description: Avestan 2383 Added: 2004-07-06 2384 %% 2385 Type: language 2386 Subtag: ar 2387 Description: Arabic 2388 Added: 2004-07-06 2389 Suppress-Script: Arab 2390 Comment: Arabic text is usually written in Arabic script 2391 %% 2392 Type: language 2393 Subtag: qaa..qtz 2394 Description: PRIVATE USE 2395 Added: 2004-08-01 2396 Comment: Use private use codes in preference 2397 to the x- singleton for primary language 2398 Comment: This is an example of two comments. 2399 %% 2400 Type: script 2401 Subtag: Arab 2402 Description: Arabic 2403 Added: 2004-07-06 2404 %% 2405 Type: script 2406 Subtag: Armn 2407 Description: Armenian 2408 Added: 2004-07-06 2409 %% 2410 Type: script 2411 Subtag: Bali 2412 Description: Balinese 2413 Added: 2004-07-06 2414 %% 2415 Type: script 2416 Subtag: Batk 2417 Description: Batak 2418 Added: 2004-07-06 2419 %% 2420 Type: region 2421 Subtag: AA 2422 Description: PRIVATE USE 2423 Added: 2004-08-01 2424 %% 2425 Type: region 2426 Subtag: AD 2427 Description: Andorra 2428 Added: 2004-07-06 2429 %% 2430 Type: region 2431 Subtag: AE 2432 Description: United Arab Emirates 2433 Added: 2004-07-06 2434 %% 2435 Type: region 2436 Subtag: AX 2437 Description: Åland Islands 2438 Added: 2004-07-06 2439 Comments: The description shows a Unicode escape 2440 for the letter A-ring. 2441 %% 2442 Type: region 2443 Subtag: 001 2444 Description: World 2445 Added: 2004-07-06 2446 %% 2447 Type: region 2448 Subtag: 002 2449 Description: Africa 2450 Added: 2004-07-06 2451 %% 2452 Type: region 2453 Subtag: 003 2454 Description: North America 2455 Added: 2004-07-06 2456 %% 2457 Type: variant 2458 Subtag: 1901 2459 Description: Traditional German 2460 orthography 2461 Added: 2004-09-09 2462 Recommended-Prefix: de 2463 Comment: 2464 %% 2465 Type: variant 2466 Subtag: 1996 2467 Description: German orthography of 1996 2468 Added: 2004-09-09 2469 Recommended-Prefix: de 2470 %% 2471 Type: variant 2472 Subtag: boont 2473 Description: Boontling 2474 Added: 2003-02-14 2475 Recommended-Prefix: en 2476 %% 2477 Type: variant 2478 Subtag: gaulish 2479 Description: Gaulish 2480 Added: 2001-05-25 2481 Recommended-Prefix: cel 2482 %% 2483 Type: grandfathered 2484 Tag: art-lojban 2485 Description: Lojban 2486 Added: 2001-11-11 2487 Canonical: jbo 2488 Deprecated: 2003-09-02 2489 %% 2490 Type: grandfathered 2491 Tag: en-GB-oed 2492 Description: English, Oxford English Dictionary spelling 2493 Added: 2003-07-09 2494 %% 2495 Type: grandfathered 2496 Tag: i-ami 2497 Description: 'Amis 2498 Added: 1999-05-25 2499 %% 2500 Type: grandfathered 2501 Tag: i-bnn 2502 Description: Bunun 2503 Added: 1999-05-25 2504 %% 2505 Type: redundant 2506 Tag: az-Arab 2507 Description: Azerbaijani in Arabic script 2508 Added: 2003-05-30 2509 %% 2510 Type: redundant 2511 Tag: az-Cyrl 2512 Description: Azerbaijani in Cyrillic script 2513 Added: 2003-05-30 2514 %% 2516 Figure 7: Example of the Registry Format 2518 Intellectual Property Statement 2520 The IETF takes no position regarding the validity or scope of any 2521 Intellectual Property Rights or other rights that might be claimed to 2522 pertain to the implementation or use of the technology described in 2523 this document or the extent to which any license under such rights 2524 might or might not be available; nor does it represent that it has 2525 made any independent effort to identify any such rights. 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