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Unicode Technical Standard #35

Unicode Locale Data Markup Language (LDML)

Version 25
Editors Mark Davis (markdavis@google.com) and other CLDR committee members
Date 2014-03-18
This Version http://www.unicode.org/reports/tr35/tr35-35/tr35.html
Previous Version http://www.unicode.org/reports/tr35/tr35-33/tr35.html
Latest Version http://www.unicode.org/reports/tr35/
Corrigenda http://unicode.org/cldr/corrigenda.html
Latest Proposed Update http://www.unicode.org/reports/tr35/proposed.html
Namespace http://cldr.unicode.org/
DTDs http://unicode.org/cldr/dtd/25/
Revision 35

Summary

This document describes an XML format (vocabulary) for the exchange of structured locale data. This format is used in the Unicode Common Locale Data Repository.

Status

This document has been reviewed by Unicode members and other interested parties, and has been approved for publication by the Unicode Consortium. This is a stable document and may be used as reference material or cited as a normative reference by other specifications.

A Unicode Technical Standard (UTS) is an independent specification. Conformance to the Unicode Standard does not imply conformance to any UTS.

Please submit corrigenda and other comments with the CLDR bug reporting form [Bugs]. Related information that is useful in understanding this document is found in the References. For the latest version of the Unicode Standard see [Unicode]. For a list of current Unicode Technical Reports see [Reports]. For more information about versions of the Unicode Standard, see [Versions].

Parts

The LDML specification is divided into the following parts:

Contents of Part 1, Core

1 Introduction

Not long ago, computer systems were like separate worlds, isolated from one another. The internet and related events have changed all that. A single system can be built of many different components, hardware and software, all needing to work together. Many different technologies have been important in bridging the gaps; in the internationalization arena, Unicode has provided a lingua franca for communicating textual data. However, there remain differences in the locale data used by different systems.

The best practice for internationalization is to store and communicate language-neutral data, and format that data for the client. This formatting can take place on any of a number of the components in a system; a server might format data based on the user's locale, or it could be that a client machine does the formatting. The same goes for parsing data, and locale-sensitive analysis of data.

But there remain significant differences across systems and applications in the locale-sensitive data used for such formatting, parsing, and analysis. Many of those differences are simply gratuitous; all within acceptable limits for human beings, but yielding different results. In many other cases there are outright errors. Whatever the cause, the differences can cause discrepancies to creep into a heterogeneous system. This is especially serious in the case of collation (sort-order), where different collation caused not only ordering differences, but also different results of queries! That is, with a query of customers with names between "Abbot, Cosmo" and "Arnold, James", if different systems have different sort orders, different lists will be returned. (For comparisons across systems formatted as HTML tables, see [Comparisons].)

Note: There are many different equally valid ways in which data can be judged to be "correct" for a particular locale. The goal for the common locale data is to make it as consistent as possible with existing locale data, and acceptable to users in that locale.

This document specifies an XML format for the communication of locale data: the Unicode Locale Data Markup Language (LDML). This provides a common format for systems to interchange locale data so that they can get the same results in the services provided by internationalization libraries. It also provides a standard format that can allow users to customize the behavior of a system. With it, for example, collation (sorting) rules can be exchanged, allowing two implementations to exchange a specification of tailored collation rules. Using the same specification, the two implementations will achieve the same results in comparing strings. Unicode LDML can also be used to let a user encapsulate specialized sorting behavior for a specific domain, or create a customized locale for a minority language. Unicode LDML is also used in the Unicode Common Locale Data Repository (CLDR). CLDR uses an open process for reconciling differences between the locale data used on different systems and validating the data, to produce with a useful, common, consistent base of locale data.

For more information, see the Common Locale Data Repository project page [LocaleProject].

As LDML is an interchange format, it was designed for ease of maintenance and simplicity of transformation into other formats, above efficiency of run-time lookup and use. Implementations should consider converting LDML data into a more compact format prior to use.

1.1 Conformance

There are many ways to use the Unicode LDML format and the data in CLDR, and the Unicode Consortium does not restrict the ways in which the format or data are used. However, an implementation may also claim conformance to LDML or to CLDR, as follows:

 

UAX35-C1. An implementation that claims conformance to this specification shall:

  1. Identify the sections of the specification that it conforms to.
    • For example, an implementation might claim conformance to all LDML features except for transforms and segments.
  2. Interpret the relevant elements and attributes of LDML documents in accordance with the descriptions in those sections.
    • For example, an implementation that claims conformance to the date format patterns must interpret the characters in such patterns according to Date Field Symbol Table.
  3. Declare which types of CLDR data that it uses.
    • For example, an implementation might declare that it only uses language names, and those with a draft status of contributed or approved.

UAX35-C2. An implementation that claims conformance to Unicode locale or language identifiers shall:

  1. Specify whether Unicode locale extensions are allowed
  2. Specify the canonical form used for identifiers in terms of casing and field separator characters.

External specifications may also reference particular components of Unicode locale or language identifiers, such as:

Field X can contain any Unicode region subtag values as given in Unicode Technical Standard #35: Unicode Locale Data Markup Language (LDML), excluding grouping codes.

2 What is a Locale?

Before diving into the XML structure, it is helpful to describe the model behind the structure. People do not have to subscribe to this model to use data in LDML, but they do need to understand it so that the data can be correctly translated into whatever model their implementation uses.

The first issue is basic: what is a locale? In this model, a locale is an identifier (id) that refers to a set of user preferences that tend to be shared across significant swaths of the world. Traditionally, the data associated with this id provides support for formatting and parsing of dates, times, numbers, and currencies; for measurement units, for sort-order (collation), plus translated names for time zones, languages, countries, and scripts. The data can also include support for text boundaries (character, word, line, and sentence), text transformations (including transliterations), and other services.

Locale data is not cast in stone: the data used on someone's machine generally may reflect the US format, for example, but preferences can typically set to override particular items, such as setting the date format for 2002.03.15, or using metric or Imperial measurement units. In the abstract, locales are simply one of many sets of preferences that, say, a website may want to remember for a particular user. Depending on the application, it may want to also remember the user's time zone, preferred currency, preferred character set, smoker/non-smoker preference, meal preference (vegetarian, kosher, and so on), music preference, religion, party affiliation, favorite charity, and so on.

Locale data in a system may also change over time: country boundaries change; governments (and currencies) come and go: committees impose new standards; bugs are found and fixed in the source data; and so on. Thus the data needs to be versioned for stability over time.

In general terms, the locale id is a parameter that is supplied to a particular service (date formatting, sorting, spell-checking, and so on). The format in this document does not attempt to represent all the data that could conceivably be used by all possible services. Instead, it collects together data that is in common use in systems and internationalization libraries for basic services. The main difference among locales is in terms of language; there may also be some differences according to different countries or regions. However, the line between locales and languages, as commonly used in the industry, are rather fuzzy. Note also that the vast majority of the locale data in CLDR is in fact language data; all non-linguistic data is separated out into a separate tree. For more information, see Section 3.10 Language and Locale IDs.

We will speak of data as being "in locale X". That does not imply that a locale is a collection of data; it is simply shorthand for "the set of data associated with the locale id X". Each individual piece of data is called a resource or field, and a tag indicating the key of the resource is called a resource tag.

3 Unicode Language and Locale Identifiers

Unicode LDML uses stable identifiers based on [BCP47] for distinguishing among languages, locales, regions, currencies, time zones, transforms, and so on. There are many systems for identifiers for these entities. The Unicode LDML identifiers may not match the identifiers used on a particular target system. If so, some process of identifier translation may be required when using LDML data.

3.1 Unicode Language Identifier

A Unicode language identifier has the following structure (provided in either EBNF (Perl-based) or ABNF [RFC5234]):

 
EBNF
ABNF
unicode_language_id
="root"
| unicode_language_subtag 
  (sep unicode_script_subtag)? 
  (sep unicode_region_subtag)?
  (sep unicode_variant_subtag)*
="root" 
/ unicode_language_subtag 
  [sep unicode_script_subtag] 
  [sep unicode_region_subtag]
  *(sep unicode_variant_subtag)
sep
= "-" | "_"
= "-" / "_"

For example, "en-US" (American English), "en_GB" (British English), "es-419" (Latin American Spanish), and "uz-Cyrl" (Uzbek in Cyrillic) are all Unicode language identifiers.

3.2 Unicode Locale Identifier

A Unicode locale identifier is composed of a Unicode language identifier plus (optional) locale extensions. It has the following

 
EBNF
ABNF
unicode_locale_id
= unicode_language_id
  transformed_extensions?
  unicode_locale_extensions?
= unicode_language_id
  [transformed_extensions]
  [unicode_locale_extensions]
unicode_locale_extensions
= sep "u"
  ((sep keyword)+
  |(sep attribute)+ (sep keyword)*)
= sep "u" 
  (1*(sep keyword)
 / 1*(sep attribute) *(sep keyword))
transformed_extensions
= sep "t"
  (("-" tlang ("-" tfield)*)
  | ("-" tfield)+)
= sep "t"
  (("-" tlang *("-" tfield))
  / 1*("-" tfield))
keyword
= key (sep type)?
= key [sep type]
key
= alphanum{2}
= 2alphanum
type
= alphanum{3,8} (sep alphanum{3,8})*
= 3*8alphanum *(sep 3*8alphanum)
attribute
= alphanum{3,8}
= 3*8alphanum
tlang
= unicode_language_subtag
  ("-" unicode_script_subtag)?
  ("-" unicode_region_subtag)?
  ("-" unicode_variant_subtag)*
= unicode_language_subtag
  ["-" unicode_script_subtag]
  ["-" unicode_region_subtag]
  *("-"unicode_variant_subtag)
tfield
= fsep ("-" alphanum{3,8})+
= fsep 1*("-" 3*8alphanum)
fsep
= [A-Z a-z] [0-9]
= ALPHA DIGIT
alphanum
= [0-9 A-Z a-z]
= ALPHA / DIGIT

For historical reasons, this is called a Unicode locale identifier. However, it really functions (with few exceptions) as a language identifier, and accesses language-based data. Except where it would be unclear, this document uses the term "locale" data loosely to encompass both types of data: for more information, see Section 3.10 Language and Locale IDs.

Although not shown in the syntax above, Unicode locale identifiers may also have [BCP47] extensions (other than "u") and private use subtags; these are not, however, relevant to their use in Unicode.

As for terminology, the term code may also be used instead of "subtag", and "territory" instead of "region". The primary language subtag is also called the base language code. For example, the base language code for "en-US" (American English) is "en" (English). The type may also be referred to as a value or key-value.

The identifiers can vary in case and in the separator characters. The "-" and "_" separators are treated as equivalent. All identifier field values are case-insensitive. Although case distinctions do not carry any special meaning, an implementation of LDML should use the casing recommendations in [BCP47], especially when a Unicode locale identifier is used for locale data exchange in software protocols. The recommendation is that: the region subtag is in uppercase, the script subtag is in title case, and all other subtags are in lowercase.

Note: The current version of CLDR uses upper case letters for variant subtags in its file names for backward compatibility reasons. This might be changed in future CLDR releases.

3.3 BCP 47 Conformance

Unicode language and locale identifiers inherit the design and the repertoire of subtags from [BCP47] Language Tags. There are some extensions and restrictions made for the use of the Unicode locale identifier in CLDR:

3.3.1 BCP 47 Language Tag Conversion

A Unicode language/locale identifier can be converted to a valid [BCP 47] language tag by performing the following transformation.

  1. Replace the "_" separators with "-"
  2. Replace the special language identifier "root" with the BCP 47 primary language tag "und"
For example,
en_USen-US
de_DE_u_co_phonebkde-DE-u-co-phonebk
rootund
root_u_cu_usdund-u-cu-usd

A valid [BCP 47] language tag can be converted to a valid Unicode language/locale identifier by performing the following transformation.

  1. Canonicalize the language tag (afterwards, there will be no extlang subtag)
  2. Replace the BCP 47 primary language subtag "und" with "root" if no script, region, or variant subtags are present
  3. If the BCP 47 primary language subtag matches the type attribute of a languageAlias element in Supplemental Data, replace the language subtag with the replacement value.
    1. If there are additional subtags in the replacement value, add them to the result, but only if there is no corresponding subtag already in the tag.
  4. If the BCP 47 region subtag matches the type attribute of a territoryAlias element in Supplemental Data, replace the language subtag with the replacement value, as follows:
    1. If there is a single territory in the replacement, use it.
    2. If there are multiple territories:
      1. Look up the most likely territory for the base language code (and script, if there is one).
      2. If that likely territory is in the list, use it.
      3. Otherwise, use the first territory in the list.

Examples

Original Result Comments
en-US en-US no changes
und root no changes
und-US und-US no changes, because region subtag is present
und-u-cu-USD root-u-cu-usd changes, because no script, region, or variant tag is present
cmn-TW zh-TW language alias
sr-CS sr-RS territory alias
sh sr-Latn multiple replacement subtags, 3.1 above
sh-Cyrl sr-Cyrl no replacement with multiple replacement subtags, 3.1 above
hy-SU hy-AM multiple territory values, 4.2 above
<territoryAlias type="SU" replacement="RU AM AZ BY EE GE KZ KG LV LT MD TJ TM UA UZ" …/>

Note: In some rare cases, BCP 47 language tags cannot be converted to valid Unicode language/locale identifiers, such as certain [BCP 47] grandfathered tags.

3.4 Field Definitions

Unicode language and locale identifier field values are provided in the following table. Note that some private-use BCP 47 field values are given specific meanings in CLDR.

Language/Locale Field Definitions
Field Allowable Characters Sample values
unicode_language_subtag

(also known as a Unicode base language code)

ASCII letters [BCP47] subtag values marked as Type: language

ISO 639-3 introduces the notion of "macrolanguages", where certain ISO 639-1 or ISO 639-2 codes are given broad semantics, and additional codes are given for the narrower semantics. For backwards compatibility, Unicode language identifiers retain use of the narrower semantics for these codes. For example:

For Use Not
Standard Chinese (Mandarin) zh cmn
Standard Arabic ar arb
Standard Malay ms zsm
Standard Swahili sw swh
Standard Uzbek uz uzn
Standard Konkani kok knn

If a language subtag matches the type attribute of a languageAlias element, then the replacement value is used instead. For example, because "swh" occurs in <languageAlias type="swh" replacement="sw"/> , "sw" must be used instead of "swh". Thus Unicode language identifiers use "ar-EG" for Standard Arabic (Egypt), not "arb-EG"; they use "zh-TW" for Mandarin Chinese (Taiwan), not "cmn-TW".

The private use codes from qfz..qtz will never be given specific semantics in Unicode identifiers, and are thus safe for use for other purposes by other applications.

The CLDR provides data for normalizing language/locale codes, including mapping overlong codes like "eng-840" or "eng-USA" to the correct code "en-US".

unicode_script_subtag

(also known as a Unicode script code)

ASCII letters [BCP47] subtag values marked as Type: script

In most cases the script is not necessary, since the language is only customarily written in a single script. Examples of cases where it is used are:

az_Arab Azerbaijani in Arabic script
az_Cyrl Azerbaijani in Cyrillic script
az_Latn Azerbaijani in Latin script
zh_Hans Chinese, in simplified script
zh_Hant Chinese, in traditional script

Unicode identifiers give specific semantics to three Unicode Script values [UAX24]:

Zyyy Common  
Qaai Inherited the preferred form is now Zinh
Zzzz Unknown  

The private use subtags from Qaaq..Qabx will never be given specific semantics in Unicode identifiers, and are thus safe for use for other purposes by other applications.

unicode_region_subtag

(also known as a Unicode region code, or a Unicode territory code)

ASCII letters and digits [BCP47] subtag values marked as Type: region

Unicode identifiers give specific semantics to the following subtags:

  Name Comment ISO 3166-1 status
QO Outlying Oceania countries in Oceania [009] that do not have a subcontinent. private use
QU European Union the preferred form is now EU private use
UK United Kingdom the correct form is GB exceptionally reserved
ZZ Unknown or Invalid Territory used in APIs or as replacement for invalid code private use

The private use subtags from XA..XZ will never be given specific semantics in Unicode identifiers, and are thus safe for use for other purposes by other applications.

The CLDR provides data for normalizing territory/region codes, including mapping overlong codes like "eng-840" or "eng-USA" to the correct code "en-US".

Special Codes:

  • The territory code 'UK' has a special status in ISO, and is used for the domain name instead of GB. It is thus recognized by CLDR as being an alternate (unnormalized) form of 'GB'.
  • The territory code '001' (the World) is used to indicate a standardized form, such as "ar-001" for Modern Standard Arabic.
unicode_variant_subtag

(also known as a Unicode language variant code)

ASCII letters [BCP47] subtag values marked as Type: variant

The CLDR provides data for normalizing variant codes.

attribute ASCII letters and digits Currently not used, reserved for future use.
key ASCII letters and digits key/type definitions are discussed below. For information on the process for adding new key/type, see [LocaleProject].

All type values except ones used for key "ka" (colAlternate) and "vt" (variableTop) are represented by a single subtag in the current version of CLDR. If the type is not included, and one of the possible type values is "true", then that value is assumed. Note that the default for key with a possible "true" value is often "false", but may not always be.

type ASCII letters and digits

Examples:

en
fr_BE
de_DE_u_co_phonebk_cu_ddm

A locale that only has a language subtag (and optionally a script subtag) is called a language locale; one with both language and territory subtag is called a territory locale (or country locale).

3.5 Key And Type Definitions

The following chart contains a set of key values that are currently available, with a description or sampling of type values. Each category is associated with an XML file in the bcp47 directory. For the complete list of valid keys and types defined for Unicode locale extensions, see Section 3.7 Unicode BCP 47 Extension Data.

The BCP47 form is the canonical form, and recommended. Other aliases are included for backwards compatibility.

Key/Type Definitions
category key
(old key name)
key description type
(old type name)
type description

Calendar

bcp47/calendar.xml

"ca"
(calendar)
Calendar algorithm

(For information on the calendar algorithms associated with the data used with these, see [Calendars].)
"buddhist" Thai Buddhist calendar (same as Gregorian except for the year)
"chinese" Traditional Chinese calendar
"gregory"
(gregorian)
Gregorian calendar
"islamic" Islamic calendar
"islamic-civil" Islamic calendar, tabular (intercalary years [2,5,7,10,13,16,18,21,24,26,29] - civil epoch)
"islamic-umalqura" Islamic calendar, Umm al-Qura
Note: Some calendar types are represented by two subtags. In such cases, the first subtag specifies a generic calendar type and the second subtag specifies a calendar algorithm variant. The CLDR uses generic calendar types (single subtag types) for tagging data when calendar algorithm variations within a generic calendar type are irrelevant. For example, type "islamic" is used for specifying Islamic calendar formatting data for all Islamic calendar types, including "islamic-civil" and "islamic-umalqura".

Collation

bcp47/collation.xml

"co"
(collation)
Collation type "standard" The default ordering for each language. For root it is based on the [DUCET] (Default Unicode Collation Element Table): see Root Collation. Each other locale is based on that, except for appropriate modifications to certain characters for that language.
"search" A special collation type dedicated for string search—it is not used to determine the relative order of two strings, but only to determine whether they should be considered equivalent for the specified strength, using the string search matching rules appropriate for the language. Compared to the normal collator for the language, this may add or remove primary equivalences, may make additional characters ignorable or change secondary equivalences, and may modify contractions to allow matching within them, depending on the desired behavior. For example, in Czech, the distinction between ‘a’ and ‘á’ is secondary for normal collation, but primary for search; a search for ‘a’ should never match ‘á’ and vice versa. A search collator is normally used with strength set to PRIMARY or SECONDARY (should be SECONDARY if using “asymmetric” search as described in the [UCA] section Asymmetric Search). The search collator in root supplies matching rules that are appropriate for most languages (and which are different than the root collation behavior); language-specific search collators may be provided to override the matching rules for a given language as necessary.

Other keywords provide additional choices for certain locales; they only have effect in certain locales.

"phonetic" Requests a phonetic variant if available, where text is sorted based on pronunciation. It may interleave different scripts, if multiple scripts are in common use.
"pinyin" Pinyin ordering for Latin and for CJK characters; that is, an ordering for CJK characters based on a character-by-character transliteration into a pinyin. (used in Chinese)
"reformed" Reformed collation (such as in Swedish)
"searchjl" Special collation type for a modified string search in which a pattern consisting of a sequence of Hangul initial consonants (jamo lead consonants) will match a sequence of Hangul syllable characters whose initial consonants match the pattern. The jamo lead consonants can be represented using conjoining or compatibility jamo. This search collator is best used at SECONDARY strength with an "asymmetric" search as described in the [UCA] section Asymmetric Search and obtained, for example, using ICU4C's usearch facility with attribute USEARCH_ELEMENT_COMPARISON set to value USEARCH_PATTERN_BASE_WEIGHT_IS_WILDCARD; this ensures that a full Hangul syllable in the search pattern will only match the same syllable in the searched text (instead of matching any syllable with the same initial consonant), while a Hangul initial consonant in the search pattern will match any Hangul syllable in the searched text with the same initial consonant.
For information on each collation setting parameter, from ka to vt, see Setting Options

Currency

bcp47/currency.xml

"cu"
(currency)
Currency type ISO 4217 code,

plus others in common use

Codes that are or have been valid in ISO 4217, plus certain additional codes that are or have been in common use. The full list of codes, with descriptions, is available in the common/main/en.xml file for each release of CLDR. The list of countries and time periods associated with each currency value is available.

The XXX code is given a broader interpretation as Unknown or Invalid Currency.

For more information, see Supplemental Currency Data.

Number

bcp47/number.xml

"nu"
(numbers)
Numbering system Unicode script subtag

Four-letter types indicating the primary numbering system for the corresponding script represented in Unicode. Unless otherwise specified, it is a decimal numbering system using digits [:GeneralCategory=Nd:]. For example, "latn" refers to the ASCII / Western digits 0-9, while "taml" is an algorithmic (non-decimal) numbering system. (The code "tamldec" is indicates the "modern Tamil decimal digits".)


For more information, see Numbering Systems.

"arabext" Extended Arabic-Indic digits ("arab" means the base Arabic-Indic digits)
"armnlow" Armenian lowercase numerals
"roman" Roman numerals
"romanlow" Roman lowercase numerals
"tamldec" Modern Tamil decimal digits

Time zone

bcp47/timezone.xml

"tz"
(timezone)
Time zone Unicode short time zone IDs

Short identifiers defined in terms of a TZ time zone database [Olson] identifier in the file common/bcp47/timezone.xml file.

For more information, see Section 3.7.1.2 Time Zone Identifiers.

The CLDR provides data for normalizing timezone codes.

Locale variant

bcp47/variant.xml

"va" Common variant type "posix" POSIX style locale variant

For more information on the allowed keys and types, see the specific elements below, and Section 3.7 Locale Extension Key and Type Data.

Additional keys or types might be added in future versions. Implementations of LDML should be robust to handle any syntactically valid key or type values.

3.6 Special Codes

3.6.1 Unknown or Invalid Identifiers

The following identifiers are used to indicate an unknown or invalid code in Unicode language and locale identifiers. For Unicode identifiers, the region code uses a private use ISO 3166 code, and Time Zone code uses an additional code; the others are defined by the relevant standards. When these codes are used in APIs connected with Unicode identifiers, the meaning is that either there was no identifier available, or that at some point an input identifier value was determined to be invalid or ill-formed.

Code Type Value Description in Referenced Standards
Language und Undetermined language
Script Zzzz Code for uncoded script, Unknown [UAX24]
Region   ZZ Unknown or Invalid Territory
Currency XXX The codes assigned for transactions where no currency is involved
Time Zone unk Unknown or Invalid Time Zone

When only the script or region are known, then a locale ID will use "und" as the language subtag portion. Thus the locale tag "und_Grek" represents the Greek script; "und_US" represents the US territory.

3.6.2 Numeric Codes

For region codes, ISO and the UN establish a mapping to three-letter codes and numeric codes. However, this does not extend to the private use codes, which are the codes 900-999 (total: 100), and AAA, QMA-QZZ, XAA-XZZ, and ZZZ (total: 1092). Unicode identifiers supply a standard mapping to these: for the numeric codes, it uses the top of the numeric private use range; for the 3-letter codes it doubles the final letter. These are the resulting mappings for all of the private use region codes:

Region UN/ISO Numeric ISO 3-Letter
AA 958 AAA
QM..QZ 959..972 QMM..QZZ
XA..XZ 973..998 XAA..XZZ
ZZ 999 ZZZ

For script codes, ISO 15924 supplies a mapping (however, the numeric codes are not in common use):

Script Numeric
Qaaa..Qabx 900..949

3.6.3 Private Use Codes

Private use codes fall into three groups.

Private Use Codes in CLDR
category status codes
base language defined none
reserved qaa..qfy
excluded qfz..qtz
script defined Qaai (obsolete)
reserved Qaaa..Qaap
excluded Qaaq..Qabx
region defined QO, QU, UK, ZZ
reserved AA, QM..QZ
excluded XA..XZ
timezone defined IANA: Etc/Unknown
bcp47: as listed in the bcp47 file
reserved bcp47: all non-5 letter codes
excluded none

See also Section 3.6.1 Unknown or Invalid Identifiers.

3.7 Unicode BCP 47 Extension Data

[BCP47] Language Tags provides a mechanism for extending language tags for use in various applications by extension subtags. Each extension subtag is identified by a single alphanumeric character subtag assigned by IANA.

The Unicode Consortium has registered and is the maintaining authority for two BCP 47 language tag extensions: the extension 'u' for Unicode locale extension [RFC6067] and extension 't' for transformed content [RFC6497]. The Unicode BCP 47 extension data defines the complete list of

These subtags are all in lowercase (that is the canonical casing for these subtags), however, subtags are case-insensitive and casing does not carry any specific meaning. All subtags within the Unicode extensions are alphanumeric characters in length of two to eight that meet the rule extension in the [BCP47]

The -u- Extension. The syntax of 'u' extension subtags is defined by the rule unicode_locale_extensions in Section 3.2 Unicode locale identifier, except the separator of subtags sep must be always hyphen '-' when the extension is used as a part of BCP 47 language tag.

A 'u' extension may contain multiple attribute s or keyword s as defined in Section 3.2 Unicode locale identifier. Although the order of attribute s or keyword s does not matter, this specification defines the canonical form as below:

For example, the canonical form of 'u' extension "u-foo-bar-nu-thai-ca-buddhist" is "u-bar-foo-ca-buddhist-nu-thai". The attributes "foo" and "bar" in this example are provided only for illustration; no attribute subtags are defined by the current CLDR specification.

The -t- Extension. The syntax of 't' extension subtags is defined by the rule unicode_locale_extensions in Section 3.2 Unicode locale identifier, except the separator of subtags sep must be always hyphen '-' when the extension is used as a part of BCP 47 language tag. For information about the registration process, meaning, and usage of the 't' extension, see [RFC6497].

See also Unicode Extensions for BCP 47 on the CLDR site.

3.7.1 Unicode Locale Extension Data Files

The 'u' extension data is stored in multiple XML files located under common/bcp47 directory in CLDR. Each file contains the locale extension key/type values and their backward compatibility mappings appropriate for a particular domain. common/bcp47/collation.xmlcontains key/type values for collation, including optional collation parameters and valid type values for each key.

The 't' extension data is stored in common/bcp47/transform.xml.

<!ELEMENT keyword ( key* )>

<!ELEMENT key ( type* )>
<!ATTLIST key extension NMTOKEN #IMPLIED>
<!ATTLIST key name NMTOKEN #REQUIRED>
<!ATTLIST key description CDATA #IMPLIED>
<!ATTLIST key deprecated ( true | false ) "false">
<!ATTLIST key preferred NMTOKEN #IMPLIED>
<!ATTLIST key alias NMTOKEN #IMPLIED>
<!ATTLIST key since CDATA #IMPLIED>

<!ELEMENT type EMPTY>
<!ATTLIST type name NMTOKEN #REQUIRED>
<!ATTLIST type description CDATA #IMPLIED>
<!ATTLIST type deprecated ( true | false ) "false">
<!ATTLIST type preferred NMTOKEN #IMPLIED>
<!ATTLIST type alias CDATA #IMPLIED>
<!ATTLIST type since CDATA #IMPLIED>

<!ELEMENT attribute EMPTY>
<!ATTLIST attribute name NMTOKEN #REQUIRED>
<!ATTLIST attribute description CDATA #IMPLIED>
<!ATTLIST attribute deprecated ( true | false ) "false">
<!ATTLIST attribute preferred NMTOKEN #IMPLIED>
<!ATTLIST attribute since CDATA #IMPLIED>

The extension attribute in <key> element specifies the BCP 47 language tag extension type. The default value of the extension attribute is "u" (Unicode locale extension). The <type> element is only applicable to the enclosing <key>.

In the Unicode locale extension 'u' data files, the common attributes for the <key>, <type> and <attribute> elements are as follows:

name

The key or type name used by Unicode locale extension with 'u' extension syntax. When alias below is absent, this name can be also used with the old style "@key=type" syntax.

The type name "CODEPOINTS" is reserved for a variable representing Unicode code point(s). The syntax is:

 
EBNF
ABNF
codepoints
= codepoint (sep codepoint)?
= codepoint *(sep codepoint)
codepoint
= [0-9 A-F a-f]{4,6}
= 4*6HEXDIG

In addition, no codepoint may exceed 10FFFF. For example, "00A0", "300b", "10D40C" and "00C1-00E1" are valid, but "A0", "U060C" and "110000" are not.

In the current version of CLDR, the type "CODEPOINTS" is only used for the locale extension key "vt" (variableTop). The subtags forming the type for "vt" represent an arbitrary string of characters. There is no formal limit in the number of characters, although practically anything above 1 will be rare, and anything longer than 4 might be useless. Repetition is allowed, for example, 0061-0061 ("aa") is a Valid type value for "vt", since the sequence may be a collating element. Order is vital: 0061-0062 ("ab") is different than 0062-0061 ("ba"). Note that for variableTop any character sequence must be a contraction which yields exactly one primary weight.

For example,

en-u-vt-00A4 : this indicates English, with any characters sorting at or below " ¤" (at a primary level) considered Variable.

By default in UCA, variable characters are ignored in sorting at a primary, secondary, and tertiary level. But in CLDR, they are not ignorable by default. For more information, see Collation: Section 3.3 Setting Options .

The type name "REORDER_CODE" is reserved for reordering block names (e.g. "latn", "digit" and "others") defined in the Root Collation. The type "REORDER_CODE" is used for locale extension key "kr" (colReorder). The value of type for "kr" is represented by one or more reordering block names such as "latn-digit". For more information, see Collation: Section 3.12 Collation Reordering .

In the current version of CLDR, all type names except "CODEPOINTS" and "REORDER_CODE" are final and used alone. For example, "gregory" and "japanese" are valid type names for key "ca" (calendar). Both "u-ca-gregory" and "u-ca-japanese" are valid representations of Unicode locale extension, but "u-ca-gregory-japanese" is not.

description

The description of the key, type or attribute element. There is also some informative text about certain keys and types in the Section 3.5 Key And Type Definitions.

deprecated

The deprecation status of the key, type or attribute element. The value "true" indicates the element is deprecated and no longer used in the version of CLDR. The default value is "false".

preferred

The preferred value of the deprecated key, type or attribute element. When a key, type or attribute element is deprecated, this attribute is used for specifying a new canonical form if available.

alias (Not applicable to <attribute>)

The BCP47 form is the canonical form, and recommended. Other aliases are included only for backwards compatibility.

Example:

<type name="phonebk" alias="phonebook" description="Phonebook style ordering (such as in German)"/>

The preferred term, and the only one to be used in BCP47, is the name: in this example, "phonebk".

The alias is a key or type name used by Unicode locale extensions with the old "@key=type" syntax. The attribute value for type may contain multiple names delimited by ASCII space characters. Of those aliases, the first name is the preferred value.

since
The version of CLDR in which this key or type was introduced. Absence of this attribute value implies the key or type was available in CLDR 1.7.2.

Note: There are no values defined for the locale extension attribute in the current CLDR release.

For example,

<key name="co" alias="collation" description="Collation type key">
  <type name="pinyin" description="Pinyin ordering for Latin and for CJK characters (used in Chinese)"/>
</key>

<key name="ka" alias="colAlternate" description="Collation parameter key for alternate handling">
  <type name="noignore" alias="non-ignorable" description="Variable collation elements are not reset to ignorable"/>
  <type name="shifted" description="Variable collation elements are reset to zero at levels one through three"/>
</key>

<key name="tz" alias="timezone">
  ...
  <type name="aumel" alias="Australia/Melbourne Australia/Victoria" description="Melbourne, Australia"/>
  <type name="aumqi" alias="Antarctica/Macquarie" description="Macquarie Island Station, Macquarie Island" since="1.8.1"/>
  ...
</key>
    
The data above indicates:
3.7.1.1 Numbering System Data

LDML supports multiple numbering systems. The identifiers for those numbering systems are defined in the file bcp47/number.xml. For example, for the 'trunk' version of the data see bcp47/number.xml.

Details about those numbering systems are defined in supplemental/numberingSystems.xml. For example, for the 'trunk' version of the data see supplemental/numberingSystems.xml.

LDML makes certain stability guarantees on this data: 

  1. Like other BCP47 identifiers, once a numeric identifier is added to bcp47/number.xml or numberingSystems.xml, it will never be removed from either of those files.
  2. If an identifier has type="numeric" in numberingSystems.xml, then
    1. It is a decimal, positional numbering system with an attribute digits=X, where X is a string with the 10 digits in order used by the numbering system.
    2. The values of the type and digits will never change.
3.7.1.2 Time Zone Identifiers

Short Time Zone Identifiers

LDML inherits time zone IDs from the tz database [Olson]. Because these IDs from the tz database do not satisfy the BCP 47 language subtag syntax requirements, CLDR defines short identifiers for the use in the Unicode locale extension. The short identifiers are defined in the file common/bcp47/timezone.xml.

The short identifiers use UN/LOCODE [LOCODE] (excluding a space character) codes where possible. For example, the short identifier for "America/Los_Angeles" is "uslax" (the LOCODE for Los Angeles, US is "US LAX"). Identifiers of length not equal to 5 are used where there is no corresponding UN/LOCODE, such as "usnavajo" for "America/Shiprock", or "utcw01" for "Etc/GMT+1", so that they do not overlap with future UN/LOCODE.

Although the first two letters of a short identifier may match an ISO 3166 two-letter country code, a user should not assume that the time zone belongs to the country. The first two letters in an identifier of length not equal to 5 has no meaning. Also, the identifiers are stabilized, meaning that they will not change no matter what changes happen in the base standard. So if Hawaii leaves the US and joins Canada as a new province, the short time zone identifier "ushnl" would not change in CLDR even if the UN/LOCODE changes to "cahnl" or something else.

There is a special code "unk" for an Unknown or Invalid time zone. This can be expressed in the tz database style ID "Etc/Unknown", although it is not defined in the tz database.

Stability of Time Zone Identifiers

Although the short time zone identifiers are guaranteed to be stable, the preferred IDs in the tz database (as those found in zone.tab file) might be changed time to time. For example, "Asia/Culcutta" was replaced with "Asia/Kolkata" and moved to backward file in the tz database. CLDR contains locale data using a time zone ID from the tz database as the key, stability of the IDs is cirtical.

To maintain the stability of "long" IDs (for those inherited from the tz database), a special rule applied to the alias attribute in the <type> element for "tz" - the first "long" ID is the CLDR canonical "long" time zone ID.

For example:

<type name="inccu" alias="Asia/Calcutta Asia/Kolkata" description="Kolkata, India"/>

Above <type> element defines the short time zone ID "inccu" (for the use in the Unicode locale extension), corresponding CLDR canonical "long" ID "Asia/Culcutta", and an alias "Asia/Kolkata".

3.7.2 Transformed Content Data File

In the transformed content 't' data file, the name attribute in a <key> element defines a valid field separator subtag. The name attribute in an enclosed <type> element defines a valid field subtag for the field separator subtag. For example:

<key extension="t" name="m0" 
    description="Transform extension mechanism">
	<type name="ungegn"
		description="United Nations Group of Experts on Geographical Names"
      since="21"/>
<key>
The data above indicates:

The attributes are:

name
The name of the mechanism, limited to 3-8 characters (or sequences of them).
description
A description of the name, with all and only that information necessary to distinguish one name from | American Library others with which it might be confused. Descriptions are not intended to provide general background information.
since
Indicates the first version of CLDR where the name appears. (Required for new items.)
 
alias
Alternative name, not limited in number of characters. Aliases are intended for compatibility, not to provide all possible alternate names or designations. (Optional)

It is strongly recommended that all API methods accept all possible aliases for keywords and types, but generate the canonical form. For example, "ar-u-ca-islamicc" would be equivalent to "ar-u-ca-islamic-civil" on input, but the latter should be output. The one exception is where an alias would only be well-formed with the old syntax, such as "gregorian" (for "gregory").

For information about the registration process, meaning, and usage of the 't' extension, see [RFC6497].

3.8 Compatibility with Older Identifiers

LDML version before 1.7.2 used slightly different syntax for variant subtags and locale extensions. Implementations of LDML may provide backward compatible identifier support as described in following sections.

3.8.1 Legacy Variants

Old LDML specification allowed codes other than registered [BCP47] variant subtags used in Unicode language and locale identifiers for representing variations of locale data. Unicode locale identifiers including such variant codes can be converted to the new [BCP47] compatible identifiers by following the descriptions below:

Legacy Variant Mappings
Variant Code Description
AALAND Åland, variant of "sv" Swedish used in Finland. Use "sv_AX" to indicate this.
BOKMAL Bokmål, variant of "no" Norwegian. Use primary language subtag "nb" to indicate this.
NYNORSK Nynorsk, variant of "no" Norwegian. Use primary language subtag "nn" to indicate this.
POSIX POSIX variation of locale data. Use Unicode locale extension "-u-va-posix" to indicate this.
POLYTONI Polytonic, variant of "el" Greek. Use [BCP47] variant subtag "polyton" to indicate this.
SAAHO The Saaho variant of Afar. Use primary language subtag "ssy" to indicated this.

3.8.2 Old Locale Extension Syntax

LDML 1.7 or older specification used different syntax for representing unicode locale extensions. The previous definition of Unicode locale extensions had the following structure:

 
EBNF
ABNF
old_unicode_locale_extensions
= "@" old_key "=" old_type
 (";" old_key "=" old_type)*
= "@" old_key "=" old_type 
*(";" old_key "=" old_type)

The new specification mandates keys to be two alphanumeric characters and types to be three to eight alphanumeric characters. As the result, new codes were assigned to all existing keys and some types. For example, a new key "co" replaced the previous key "collation", a new type "phonebk" replaced the previous type "phonebook". However, the existing collation type "big5han" already satisfied the new requirement, so no new type code was assigned to the type. The chart below shows some example mappings between the new syntax and the old syntax.

Where the old API is supplied the bcp47 language code, or vice versa, the recommendation is to:

  1. Have all methods that take the old syntax also take the new syntax, interpreted correctly. For example, "zh-TW-u-co-pinyin" and "zh_TW@collation=pinyin" would both be interpreted as meaning the same.
  2. Have all methods (both for old and new syntax) accept all possible aliases for keywords and types. For example, "ar-u-ca-islamicc" would be equivalent to "ar-u-ca-islamic-civil".
    • The one exception is where an alias would only be well-formed with the old syntax, such as "gregorian" (for "gregory").
  3. Where an API cannot successfully accept the alternate syntax, throw an exception (or otherwise indicate an error) so that people can detect that they are using the wrong method (or wrong input).
  4. Provide a method that tests a purported locale ID string to determine its status:
    1. well-formed - syntactically correct
    2. valid - well-formed and only uses registered language subtags, extensions, keywords, types...
    3. canonical - valid and no deprecated codes or structure.
Locale Extension Mappings
Old (LDML 1.7 or older) New
de_DE@collation=phonebook de_DE_u_co_phonebk
zh_Hant_TW@collation=big5han zh_Hant_TW_u_co_big5han
th_TH@calendar=gregorian;numbers=thai th_TH_u_ca_gregory_nu_thai
en_US_POSIX@timezone=America/Los_Angeles en_US_u_tz_uslax_va_posix

3.8.3 Relation to OpenI18n

The locale id format generally follows the description in the OpenI18N Locale Naming Guideline [NamingGuideline], with some enhancements. The main differences from the those guidelines are that the locale id:

  1. does not include a charset (since the data in LDML format always provides a representation of all Unicode characters. The repository is stored in UTF-8, although that can be transcoded to other encodings as well.),
  2. adds the ability to have a variant, as in Java
  3. adds the ability to discriminate the written language by script (or script variant).
  4. is a superset of [BCP47] codes.

3.9 Transmitting Locale Information

In a world of on-demand software components, with arbitrary connections between those components, it is important to get a sense of where localization should be done, and how to transmit enough information so that it can be done at that appropriate place. End-users need to get messages localized to their languages, messages that not only contain a translation of text, but also contain variables such as date, time, number formats, and currencies formatted according to the users' conventions. The strategy for doing the so-called JIT localization is made up of two parts:

  1. Store and transmit neutral-format data wherever possible.
    • Neutral-format data is data that is kept in a standard format, no matter what the local user's environment is. Neutral-format is also (loosely) called binary data, even though it actually could be represented in many different ways, including a textual representation such as in XML.
    • Such data should use accepted standards where possible, such as for currency codes.
    • Textual data should also be in a uniform character set (Unicode/10646) to avoid possible data corruption problems when converting between encodings.
  2. Localize that data as "close" to the end-user as possible.

There are a number of advantages to this strategy. The longer the data is kept in a neutral format, the more flexible the entire system is. On a practical level, if transmitted data is neutral-format, then it is much easier to manipulate the data, debug the processing of the data, and maintain the software connections between components.

Once data has been localized into a given language, it can be quite difficult to programmatically convert that data into another format, if required. This is especially true if the data contains a mixture of translated text and formatted variables. Once information has been localized into, say, Romanian, it is much more difficult to localize that data into, say, French. Parsing is more difficult than formatting, and may run up against different ambiguities in interpreting text that has been localized, even if the original translated message text is available (which it may not be).

Moreover, the closer we are to end-user, the more we know about that user's preferred formats. If we format dates, for example, at the user's machine, then it can easily take into account any customizations that the user has specified. If the formatting is done elsewhere, either we have to transmit whatever user customizations are in play, or we only transmit the user's locale code, which may only approximate the desired format. Thus the closer the localization is to the end user, the less we need to ship all of the user's preferences around to all the places that localization could possibly need to be done.

Even though localization should be done as close to the end-user as possible, there will be cases where different components need to be aware of whatever settings are appropriate for doing the localization. Thus information such as a locale code or time zone needs to be communicated between different components.

3.9.1 Message Formatting and Exceptions

Windows (FormatMessage, String.Format), Java (MessageFormat) and ICU (MessageFormat, umsg) all provide methods of formatting variables (dates, times, etc) and inserting them at arbitrary positions in a string. This avoids the manual string concatenation that causes severe problems for localization. The question is, where to do this? It is especially important since the original code site that originates a particular message may be far down in the bowels of a component, and passed up to the top of the component with an exception. So we will take that case as representative of this class of issues.

There are circumstances where the message can be communicated with a language-neutral code, such as a numeric error code or mnemonic string key, that is understood outside of the component. If there are arguments that need to accompany that message, such as a number of files or a datetime, those need to accompany the numeric code so that when the localization is finally at some point, the full information can be presented to the end-user. This is the best case for localization.

More often, the exact messages that could originate from within the component are not known outside of the component itself; or at least they may not be known by the component that is finally displaying text to the user. In such a case, the information as to the user's locale needs to be communicated in some way to the component that is doing the localization. That locale information does not necessarily need to be communicated deep within the component; ideally, any exceptions should bundle up some language-neutral message ID, plus the arguments needed to format the message (for example, datetime), but not do the localization at the throw site. This approach has the advantages noted above for JIT localization.

In addition, exceptions are often caught at a higher level; they do not end up being displayed to any end-user at all. By avoiding the localization at the throw site, it the cost of doing formatting, when that formatting is not really necessary. In fact, in many running programs most of the exceptions that are thrown at a low level never end up being presented to an end-user, so this can have considerable performance benefits.

3.10 Unicode Language and Locale IDs

People have very slippery notions of what distinguishes a language code versus a locale code. The problem is that both are somewhat nebulous concepts.

In practice, many people use [BCP47] codes to mean locale codes instead of strictly language codes. It is easy to see why this came about; because [BCP47] includes an explicit region (territory) code, for most people it was sufficient for use as a locale code as well. For example, when typical web software receives an [BCP47] code, it will use it as a locale code. Other typical software will do the same: in practice, language codes and locale codes are treated interchangeably. Some people recommend distinguishing on the basis of "-" versus "_" (for example, zh-TW for language code, zh_TW for locale code), but in practice that does not work because of the free variation out in the world in the use of these separators. Notice that Windows, for example, uses "-" as a separator in its locale codes. So pragmatically one is forced to treat "-" and "_" as equivalent when interpreting either one on input.

Another reason for the conflation of these codes is that very little data in most systems is distinguished by region alone; currency codes and measurement systems being some of the few. Sometimes date or number formats are mentioned as regional, but that really does not make much sense. If people see the sentence "You will have to adjust the value to १,२३४.५६७ from ૭૧,૨૩૪.૫૬" (using Indic digits), they would say that sentence is simply not English. Number format is far more closely associated with language than it is with region. The same is true for date formats: people would never expect to see intermixed a date in the format "2003年4月1日" (using Kanji) in text purporting to be purely English. There are regional differences in date and number format — differences which can be important — but those are different in kind than other language differences between regions.

As far as we are concerned — as a completely practical matter — two languages are different if they require substantially different localized resources. Distinctions according to spoken form are important in some contexts, but the written form is by far and away the most important issue for data interchange. Unfortunately, this is not the principle used in [ISO639], which has the fairly unproductive notion (for data interchange) that only spoken language matters (it is also not completely consistent about this, however).

[BCP47] can express a difference if the use of written languages happens to correspond to region boundaries expressed as [ISO3166] region codes, and has recently added codes that allow it to express some important cases that are not distinguished by [ISO3166] codes. These written languages include simplified and traditional Chinese (both used in Hong Kong S.A.R.); Serbian in Latin script; Azerbaijani in Arab script, and so on.

Notice also that currency codes are different than currency localizations. The currency localizations should largely be in the language-based resource bundles, not in the territory-based resource bundles. Thus, the resource bundle en contains the localized mappings in English for a range of different currency codes: USD → US$, RUR → Rub, AUD → $A and so on. Of course, some currency symbols are used for more than one currency, and in such cases specializations appear in the territory-based bundles. Continuing the example, en_US would have USD → $, while en_AU would have AUD → $. (In protocols, the currency codes should always accompany any currency amounts; otherwise the data is ambiguous, and software is forced to use the user's territory to guess at the currency. For some informal discussion of this, see JIT Localization.)

3.10.1 Written Language

Criteria for what makes a written language should be purely pragmatic; what would copy-editors say? If one gave them text like the following, they would respond that is far from acceptable English for publication, and ask for it to be redone:

  1. "Theatre Center News: The date of the last version of this document was 2003年3月20日. A copy can be obtained for $50,0 or 1.234,57 грн. We would like to acknowledge contributions by the following authors (in alphabetical order): Alaa Ghoneim, Behdad Esfahbod, Ahmed Talaat, Eric Mader, Asmus Freytag, Avery Bishop, and Doug Felt."

So one would change it to either B or C below, depending on which orthographic variant of English was the target for the publication:

  1. "Theater Center News: The date of the last version of this document was 3/20/2003. A copy can be obtained for $50.00 or 1,234.57 Ukrainian Hryvni. We would like to acknowledge contributions by the following authors (in alphabetical order): Alaa Ghoneim, Ahmed Talaat, Asmus Freytag, Avery Bishop, Behdad Esfahbod, Doug Felt, Eric Mader."
  2. "Theatre Centre News: The date of the last version of this document was 20/3/2003. A copy can be obtained for $50.00 or 1,234.57 Ukrainian Hryvni. We would like to acknowledge contributions by the following authors (in alphabetical order): Alaa Ghoneim, Ahmed Talaat, Asmus Freytag, Avery Bishop, Behdad Esfahbod, Doug Felt, Eric Mader."

Clearly there are many acceptable variations on this text. For example, copy editors might still quibble with the use of first versus last name sorting in the list, but clearly the first list was not acceptable English alphabetical order. And in quoting a name, like "Theatre Centre News", one may leave it in the source orthography even if it differs from the publication target orthography. And so on. However, just as clearly, there limits on what is acceptable English, and "2003年3月20日", for example, is not.

Note that the language of locale data may differ from the language of localized software or web sites, when those latter are not localized into the user's preferred language. In such cases, the kind of incongruous juxtapositions described above may well appear, but this situation is usually preferable to forcing unfamiliar date or number formats on the user as well.

4 Locale Inheritance and Matching

The XML format relies on an inheritance model, whereby the resources are collected into bundles, and the bundles organized into a tree. Data for the many Spanish locales does not need to be duplicated across all of the countries having Spanish as a national language. Instead, common data is collected in the Spanish language locale, and territory locales only need to supply differences. The parent of all of the language locales is a generic locale known as root. Wherever possible, the resources in the root are language & territory neutral. For example, the collation (sorting) order in the root is based on the [DUCET] (seeRoot Collation). Since English language collation has the same ordering as the root locale, the 'en' locale data does not need to supply any collation data, nor does either the 'en_US' or the 'en_IE' locale data.

Given a particular locale id "en_IE_someVariant", the search chain for a particular resource is the following.

en_IE_someVariant
en_IE
en
root

If a type and key are supplied in the locale id, then logically the chain from that id to the root is searched for a resource tag with a given type, all the way up to root. If no resource is found with that tag and type, then the chain is searched again without the type.

Thus the data for any given locale will only contain resources that are different from the parent locale. For example, most territory locales will inherit the bulk of their data from the language locale: "en" will contain the bulk of the data: "en_IE" will only contain a few items like currency. All data that is inherited from a parent is presumed to be valid, just as valid as if it were physically present in the file. This provides for much smaller resource bundles, and much simpler (and less error-prone) maintenance. At the script or region level, the "primary" child locale will be empty, since its parent will contain all of the appropriate resources for it. For more information see CLDR Information : Section 9.3 Default Content.

Certain data items depend only on the region specified in a locale id, and are obtained from supplemental data rather than through locale resources. For example:

These items will be correct for the specified region regardless of whether a locale bundle actually exists with the same combination of language and region as in the locale id. For example, suppose data is requested for the locale id "fr_US" and there is no bundle for that combination. Data obtained via locale inheritance, such as currency patterns and currency symbols, will be obtained from the parent locale "fr". However, currency amounts would be formatted by default using US dollars, just displayed in the manner governed by the locale "fr". When a locale id does not specify a region, the region-specific items such as those above are obtained from the likely region for the locale (obtained via Likely Subtags).

If a language has more than one script in customary modern use, then the CLDR file structure in common/main follows the following model:

lang
lang_script
lang_script_region
lang_region (aliases to lang_script_region)

There are actually two different kinds of fallback: resource bundle lookup and resource item lookup. For the former, a process is looking to find the first, best resource bundle it can; for the later, it is fallback within bundles on individual items, like a the translated name for the region "CN" in Breton. These are closely related, but distinct, processes. Below "key" stands for zero or more key/type pairs.

Lookup Differences

Lookup Type
 

Example
 

Comments
 

Resource bundle lookup

se-FI → se
  → default*
  → root

* default may have its own inheritance change; for example, it may be "en-GB → en" In that case, the chain is expanded by inserting the chain, resulting in:
se-FI → se
  → fi → en-GB → en
  → root 

Resource item lookup

se-FI+key → se+key
  → root_alias*+key → root+key

* if there is a root_alias to another key or locale, then insert that entire chain. For example, suppose that months for another calendar system have a root alias to Gregorian months. In that case, the root alias would change the key, and retry from se-FI downward.
se-FI+key → se+key
  → root_alias*+key
  → se-FI+key2 → se+key2
  → root_alias*+key2 → root+key2

The fallback is a bit different for these two cases; internal aliases and keys are are not involved in the bundle lookup, and the default locale is not involved in the item lookup. Moreover, the resource item lookup must remain stable, because the resources are built with a certain fallback in mind; changing the core fallback order can render the bundle structure incoherent. Resource bundle lookup, on the other hand, is more flexible; changes in the view of the "best" match between the input request and the output bundle are more tolerant, when represent overall improvements for users. For more information, see Section 8.1 Element fallback.

Where the LDML inheritance relationship does not match a target system, such as POSIX, the data logically should be fully resolved in converting to a format for use by that system, by adding all inherited data to each locale data set.

For a more complete description of how inheritance applies to data, and the use of keywords, see Section 4.2 Inheritance .

The locale data does not contain general character properties that are derived from the Unicode Character Database [UAX44]. That data being common across locales, it is not duplicated in the bundles. Constructing a POSIX locale from the CLDR data requires use of UCD data. In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding.

Warning: If a locale has a different script than its parent (for example, sr_Latn), then special attention must be paid to make sure that all inheritance is covered. For example, auxiliary exemplar characters may need to be empty ("[]") to block inheritance.

Empty Override: There is one special value reserved in LDML to indicate that a child locale is to have no value for a path, even if the parent locale has a value for that path. That value is "∅∅∅". For example, if there is no phrase for "two days ago" in a language, that can be indicated with:

<field type="day">
  <relative type="-2">∅∅∅</relative>

4.1 Multiple Inheritance

In clearly specified instances, resources may inherit from within the same locale. For example, currency format symbols inherit from the number format symbols; the Buddhist calendar inherits from the Gregorian calendar. This only happens where documented in this specification. In these special cases, the inheritance functions as normal, up to the root. If the data is not found along that path, then a second search is made, logically changing the element/attribute to the alternate values.

For example, for the locale "en_US" the month data in <calendar class="buddhist"> inherits first from <calendar class="buddhist"> in "en", then in "root". If not found there, then it inherits from <calendar type="gregorian"> in "en_US", then "en", then in "root".

There is one special case, for items with a "count" parameter (used to select a plural form). In that case, the inheritance works as follows:

If there is no value for a path, and that path has a [@count="x"] attribute and value, then:

  1. If "x" is anything but "other", it falls back to [@count="other"], within that the same locale.
  2. In the special case of currencies, if the [@count="other"] value is missing, it falls back to the path that is completely missing the count item.
  3. If there is no value within the same locale, the same process is used in the parent locale, and so on.

Examples:

Count Fallback: normal
Locale Path
fr-CA //ldml/units/unitLength[@type="narrow"]/unit[@type="mass-gram"]/unitPattern[@count="x"]
fr-CA //ldml/units/unitLength[@type="narrow"]/unit[@type="mass-gram"]/unitPattern[@count="other"]
fr //ldml/units/unitLength[@type="narrow"]/unit[@type="mass-gram"]/unitPattern[@count="x"]
fr //ldml/units/unitLength[@type="narrow"]/unit[@type="mass-gram"]/unitPattern[@count="other"]
root //ldml/units/unitLength[@type="narrow"]/unit[@type="mass-gram"]/unitPattern[@count="x"]
root //ldml/units/unitLength[@type="narrow"]/unit[@type="mass-gram"]/unitPattern[@count="other"]

Note that there may be an alias in root that changes the path and starts again from the requested locale, such as:

<unitLength type="narrow">
   <alias source="locale" path="../unitLength[@type='short']"/>
</unitLength>

Count Fallback: currency
Locale Path
fr-CA //ldml/numbers/currencies/currency[@type="CAD"]/displayName[@count="x"]
fr-CA //ldml/numbers/currencies/currency[@type="CAD"]/displayName[@count="other"]
fr-CA //ldml/numbers/currencies/currency[@type="CAD"]/displayName
fr //ldml/numbers/currencies/currency[@type="CAD"]/displayName[@count="x"]
fr //ldml/numbers/currencies/currency[@type="CAD"]/displayName[@count="other"]
fr //ldml/numbers/currencies/currency[@type="CAD"]/displayName
root //ldml/numbers/currencies/currency[@type="CAD"]/displayName[@count="x"]
root //ldml/numbers/currencies/currency[@type="CAD"]/displayName[@count="other"]
root //ldml/numbers/currencies/currency[@type="CAD"]/displayName

4.1.1 Parent Locales

<!ELEMENT parentLocales ( parentLocale* ) >
<!ELEMENT parentLocale EMPTY >
<!ATTLIST parentLocale parent CDATA #REQUIRED >
<!ATTLIST parentLocale locales CDATA #REQUIRED >

In some cases, the normal truncation inheritance does not function well. This happens when:

  1. The child locale is of a different script. In this case, mixing elements from the parent into the child data results in a mishmash.
  2. A large number of child locales behave similarly, and differently from the truncation parent.

The parentLocale element is used to override the normal inheritance when accessing CLDR data.

For case 1, the children are script locales, and the parent is "root". For example:

 <parentLocale parent="root" locales="az_Cyrl ha_Arab … zh_Hant"/>

For case 2, the children and parent share the same primary language, but the region is changed. For example:

 <parentLocale parent="es_419" locales="es_AR es_BO … es_UY es_VE"/>

Collation data, however, is an exception. Since collation rules do not truly inherit data from the parent, the parentLocale element is not necessary and not used for collation. Thus, for a locale like zh_Hant in the example above, the parentLocale element would dictate the parent as "root" when referring to main locale data, but for collation data, the parent locale would still be "zh", even though the parentLocale element is present for that locale.

4.2 Inheritance and Validity

The following describes in more detail how to determine the exact inheritance of elements, and the validity of a given element in LDML.

4.2.1 Definitions

Blocking elements are those whose subelements do not inherit from parent locales. For example, a <collation> element is a blocking element: everything in a <collation> element is treated as a single lump of data, as far as inheritance is concerned. For more information, see Section 5.5 Valid Attribute Values.

Attributes that serve to distinguish multiple elements at the same level are called distinguishing attributes. For example, the type attribute distinguishes different elements in lists of translations, such as:

<language type="aa">Afar</language>
<language type="ab">Abkhazian</language>

Distinguishing attributes affect inheritance; two elements with different distinguishing attributes are treated as different for purposes of inheritance. For more information, see Section 5.5 Valid Attribute Values. Other attributes are called nondistinguishing (or informational) attributes. These carry separate information, and do not affect inheritance.

For any element in an XML file, an element chain is a resolved [XPath] leading from the root to an element, with attributes on each element in alphabetical order. So in, say, http://unicode.org/cldr/data/common/main/el.xml we may have:

<ldml>
  <identity>
    <version number="1.1" />
    <generation date="2004-06-04" />
    <language type="el" />
  </identity>
  <localeDisplayNames>
    <languages>
      <language type="ar">Αραβικά</language>
...

Which gives the following element chains (among others):

An element chain A is an extension of an element chain B if B is equivalent to an initial portion of A. For example, #2 below is an extension of #1. (Equivalent, depending on the tree, may not be "identical to". See below for an example.)

  1. //ldml/localeDisplayNames
  2. //ldml/localeDisplayNames/languages/language[@type="ar"]

An LDML file can be thought of as an ordered list of element pairs: <element chain, data>, where the element chains are all the chains for the end-nodes. (This works because of restrictions on the structure of LDML, including that it does not allow mixed content.) The ordering is the ordering that the element chains are found in the file, and thus determined by the DTD.

For example, some of those pairs would be the following. Notice that the first has the null string as element contents.

Note: There are two exceptions to this:

  1. Blocking nodes and their contents are treated as a single end node.
  2. In terms of computing inheritance, the element pair consists of the element chain plus all distinguishing attributes; the value consists of the value (if any) plus any nondistinguishing attributes.

Thus instead of the element pair being (a) below, it is (b):

  1. <//ldml/dates/calendars/calendar[@type='gregorian']/week/weekendStart[@day='sun'][@time='00:00'],
    "">
  2. <//ldml/dates/calendars/calendar[@type='gregorian']/week/weekendStart,
    [@day='sun'][@time='00:00']>

Two LDML element chains are equivalent when they would be identical if all attributes and their values were removed — except for distinguishing attributes. Thus the following are equivalent:

For any locale ID, an locale chain is an ordered list starting with the root and leading down to the ID. For example:

<root, de, de_DE, de_DE_xxx>

4.2.2 Resolved Data File

To produce fully resolved locale data file from CLDR for a locale ID L, you start with L, and successively add unique items from the parent locales until you get up to root. More formally, this can be expressed as the following procedure.

  1. Let Result be initially L.
  2. For each Li in the locale chain for L, starting at L and going up to root:
    1. Let Temp be a copy of the pairs in the LDML file for Li
    2. Replace each alias in Temp by the resolved list of pairs it points to.
      1. The resolved list of pairs is obtained by recursively applying this procedure.
      2. That alias now blocks any inheritance from the parent. (See Section 5.1 Common Elements for an example.)
    3. For each element pair P in Temp:
      1. If P does not contain a blocking element, and Result does not have an element pair Q with an equivalent element chain, add P to Result.

Notes:

4.2.3 Valid Data

The attribute draft="x" in LDML means that the data has not been approved by the subcommittee. (For more information, see Process). However, some data that is not explicitly marked as draft may be implicitly draft, either because it inherits it from a parent, or from an enclosing element.

Example 2. Suppose that new locale data is added for af (Afrikaans). To indicate that all of the data is unconfirmed, the attribute can be added to the top level.

<ldml version="1.1" draft="unconfirmed">
 <identity>
  <version number="1.1" />
  <generation date="2004-06-04" />
  <language type="af" />
 </identity>
 <characters>...</characters>
 <localeDisplayNames>...</localeDisplayNames>
</ldml>

Any data can be added to that file, and the status will all be draft=unconfirmed. Once an item is vetted—whether it is inherited or explicitly in the file—then its status can be changed to approved. This can be done either by leaving draft="unconfirmed" on the enclosing element and marking the child with draft="approved", such as:

<ldml version="1.1" draft="unconfirmed">
 <identity>
  <version number="1.1" />
  <generation date="2004-06-04" />
  <language type="af" />
 </identity>
 <characters draft="approved">...</characters>
 <localeDisplayNames>...</localeDisplayNames>
 <dates/>
 <numbers/>
 <collations/>
</ldml>

However, normally the draft attributes should be canonicalized, which means they are pushed down to leaf nodes as described in Section 5.6 Canonical Form. If an LDML file does has draft attributes that are not on leaf nodes, the file should be interpreted as if it were the canonicalized version of that file.

The attribute validSubLocales allows sublocales in a given tree to be treated as though a file for them were present when there is not one. It only has an effect for locales that inherit from the current file where a file is missing, and the elements would

Example 1. Suppose that in a particular LDML tree, there are no region locales for German, for example, there is a de.xml file, but no files for de_AT.xml, de_CH.xml, or de_DE.xml. Then no elements are valid for any of those region locales. If we want to mark one of those files as having valid elements, then we introduce an empty file, such as the following.

<ldml version="1.1">
 <identity>
  <version number="1.1" />
  <generation date="2004-06-04" />
  <language type="de" />
  <territory type="AT" />
 </identity>
</ldml>

With the validSubLocales attribute, instead of adding the empty files for de_AT.xml, de_CH.xml, and de_DE.xml, in the de file we can add to the parent locale a list of the child locales that should behave as if files were present.

<ldml version="1.1" validSubLocales="de_AT de_CH de_DE">
 <identity>
  <version number="1.1" />
  <generation date="2004-06-04" />
  <language type="de" />
 </identity>
...
</ldml>

More formally, here is how to determine whether data for an element chain E is implicitly or explicitly draft, given a locale L. Sections 1, 2, and 4 are simply formalizations of what is in LDML already. Item 3 adds the new element.

4.2.4 Checking for Draft Status

  1. Parent Locale Inheritance
    1. Walk through the locale chain until you find a locale ID L' with a data file D. (L' may equal L).
    2. Produce the fully resolved data file D' for D.
    3. In D', find the first element pair whose element chain E' is either equivalent to or an extension of E.
    4. If there is no such E', return true
    5. If E' is not equivalent to E, truncate E' to the length of E.
  2. Enclosing Element Inheritance
    1. Walk through the elements in E', from back to front.
      1. If you ever encounter draft=x, return x
    2. If L' = L, return false
  3. Missing File Inheritance
    1. Otherwise, walk again through the elements in E', from back to front.
      1. If you encounter a validSubLocales attribute:
        1. If L is in the attribute value, return false
        2. Otherwise return true
  4. Otherwise
    1. Return true

The validSubLocales in the most specific (farthest from root file) locale file "wins" through the full resolution step (data from more specific files replacing data from less specific ones).

4.2.5 Keyword and Default Resolution

When accessing data based on keywords, the following process is used. Consider the following example:

Here are the searches for various combinations.

User Input Lookup in Locale For Comment
de_CH
no keyword
de_CH default collation type finds "B"
de_CH collation type=B not found
de collation type=B found
de
no keyword
de default collation type not found
root default collation type finds "standard"
de collation type=standard not found
root collation type=standard found
de_u_co_A de collation type=A found
de_u_co_standard de collation type=standard not found
root collation type=standard found
de_u_co_foobar de collation type=foobar not found
root collation type=foobar not found, starts looking for default
de default collation type not found
root default collation type finds "standard"
de collation type=standard not found
root collation type=standard found

Examples of "search" collator lookup; 'de' has a language-specific version, but 'en' does not:

User Input Lookup in Locale For Comment
de_CH_u_co_search de_CH collation type=search not found
de collation type=search found
en_US_u_co_search en_US collation type=search not found
en collation type=search not found
root collation type=search found

Examples of lookup for Chinese collation types. Note:

User Input Lookup in Locale For Comment
zh_Hant
no keyword
zh_Hant default collation type finds "stroke"
zh_Hant collation type=stroke not found
zh collation type=stroke found
zh_Hant_HK_u_co_pinyin zh_Hant_HK collation type=pinyin not found
zh_Hant collation type=pinyin not found
zh collation type=pinyin found
zh
no keyword
zh default collation type finds "pinyin"
zh collation type=pinyin found

Note: It is an invariant that the default in root for a given element must
always be a value that exists in root. So you can not have the following in root:

<someElements>
  <default type='a'/>
  <someElement type='b'>...</someElement>
  <someElement type='c'>...</someElement>
  <!-- no 'a' -->
</someElements>

For identifiers, such as language codes, script codes, region codes, variant codes, types, keywords, currency symbols or currency display names, the default value is the identifier itself whenever if no value is found in the root. Thus if there is no display name for the region code 'QA' in root, then the display name is simply 'QA'.

4.3 Likely Subtags

<!ELEMENT likelySubtag EMPTY >
<!ATTLIST likelySubtag from NMTOKEN #REQUIRED>
<!ATTLIST likelySubtag to NMTOKEN #REQUIRED>

There are a number of situations where it is useful to be able to find the most likely language, script, or region. For example, given the language "zh" and the region "TW", what is the most likely script? Given the script "Thai" what is the most likely language or region? Given the region TW, what is the most likely language and script?

Conversely, given a locale, it is useful to find out which fields (language, script, or region) may be superfluous, in the sense that they contain the likely tags. For example, "en_Latn" can be simplified down to "en" since "Latn" is the likely script for "en"; "ja_Jpan_JP" can be simplified down to "ja".

The likelySubtag supplemental data provides default information for computing these values. This data is based on the default content data, the population data, and the the suppress-script data in [BCP47]. It is heuristically derived, and may change over time.

To look up data in the table, see if a locale matches one of the from attribute values. If so, fetch the corresponding to attribute value. For example, the Chinese data looks like the following:

<likelySubtag from="zh" to="zh_Hans_CN"/>
<likelySubtag from="zh_HK" to="zh_Hant_HK"/>
<likelySubtag from="zh_Hani" to="zh_Hani_CN"/>
<likelySubtag from="zh_Hant" to="zh_Hant_TW"/>
<likelySubtag from="zh_MO" to="zh_Hant_MO"/>
<likelySubtag from="zh_TW" to="zh_Hant_TW"/>

So looking up "zh_TW" returns "zh_Hant_TW", while looking up "zh" returns "zh_Hans_CN".

In more detail, the data is designed to be used in the following operations.

Note that as of CLDR v24, any field present in the 'from' field, is also present in the 'to' field, so an input field will not change in "Add Likely Subtags" operation. The data and operations can also be used with language tags using [BCP47] syntax, with the appropriate changes. In addition, certain common 'denormalized' language subtags such as 'iw' (for 'he') may occur in both the 'from' and 'to' fields. This allows for implementations that use those denormalized subtags to use the data with only minor changes to the operations.

 

Add Likely Subtags: Given a source locale X, to return a locale Y where the empty subtags have been filled in by the most likely subtags. This is written as X ⇒ Y ("X maximizes to Y").

A subtag is called empty if it is a missing script or region subtag, or it is a base language subtag with the value "und". In the description below, a subscript on a subtag x indicates which tag it is from: xs is in the source, xmis in a match, and xr is in the final result.

This operation is performed in the following way.

  1. Canonicalize.
    1. Make sure the input locale is in canonical form: uses the right separator, and has the right casing.
    2. Replace any deprecated subtags with their canonical values using the <alias> data in supplemental metadata. Use the first value in the replacement list, if it exists. Language tag replacements may have multiple parts, such as "sh" ➞ "sr_Latn" or mo" ➞ "ro_MD". In such a case, the original script and/or region are retained if there is one. Thus "sh_Arab_AQ" ➞ "sr_Arab_AQ", not "sr_Latn_AQ".
    3. If the tag is grandfathered (see <variable id="$grandfathered" type="choice"> in the supplemental data), then return it.
    4. Remove the script code 'Zzzz' and the region code 'ZZ' if they occur.
    5. Get the components of the cleaned-up source tag (languages, scripts, and regions), plus any variants and extensions.
  2. Lookup. Lookup each of the following in order, and stop on the first match:
    1. languages_scripts_regions
    2. languages_regions
    3. languages_scripts
    4. languages
    5. und_scripts
  3. Return
    1. If there is no match,either return
      1. an error value, or
      2. the match for "und" (in APIs where a valid language tag is required).
    2. Otherwise there is a match = languagem_scriptm_regionm
    3. Let xr = xs if xs is not empty, and xm otherwise.
    4. Return the language tag composed of languager _ scriptr _ regionr + variants + extensions .

The lookup can be optimized. For example, if any of the tags in Step 2 are the same as previous ones in that list, they do not need to be tested.

Example1:

To find the most likely language for a country, or language for a script, use "und" as the language subtag. For example, looking up "und_TW" returns zh_Hant_TW.

A goal of the algorithm is that if X ⇒ Y, and X' results from replacing an empty subtag in X by the the corresponding subtag in Y, then X' ⇒ Y. For example, if und_AF ⇒ fa_Arab_AF, then:

There are a small number of exceptions to this goal in the current data, where X ∈ {und_Bopo, und_Brai, und_Cakm, und_Limb, und_Shaw}.

Remove Likely Subtags: Given a locale, remove any fields that Add Likely Subtags would add.

The reverse operation removes fields that would be added by the first operation.

  1. First get max = AddLikelySubtags(inputLocale). If an error is signaled, return it.
  2. Remove the variants from max.
  3. Then for trial in {language, language _ region, language _ script}
    • If AddLikelySubtags(trial) = max, then return trial + variants.
  4. If you do not get a match, return max + variants.

Example:

A variant of this favors the script over the region, thus using {language, language_script, language_region} in the above. If that variant is used, then the result in this example would be zh_Hant instead of zh_TW.


		

4.4 Language Matching

<!ELEMENT languageMatching ( languageMatches* ) >
<!ELEMENT languageMatches ( languageMatch* ) >
<!ATTLIST languageMatches type NMTOKEN #REQUIRED >
<!ELEMENT languageMatch EMPTY >
<!ATTLIST languageMatch desired CDATA #REQUIRED >
<!ATTLIST languageMatch supported CDATA #REQUIRED >
<!ATTLIST languageMatch percent NMTOKEN #REQUIRED >
<!ATTLIST languageMatch oneway ( true | false ) #IMPLIED >

Implementers are often faced with the issue of how to match the user's requested languages with their product's supported languages. For example, suppose that a product supports {ja-JP, de, zh-TW}. If the user understands written American English, German, French, Swiss German, and Italian, then de would be the best match; if s/he understands only Chinese (zh), then zh-TW would be the best match.

The standard truncation-fallback algorithm does not work well when faced with the complexities of natural language. The language matching data is designed to fill that gap. Stated in those terms, language matching can have the effect of a more complex fallback, such as:

sr-Cyrl-RS
sr-Cyrl
sr-Latn-RS
sr-Latn
sr
hr-Latn
hr

Language matching is used to find the best supported locale ID given a requested list of languages. The requested list could come from different sources, such as such as the user's list of preferred languages in the OS Settings, or from a browser Accept-Language list. For example, if my native tongue is English, I can understand Swiss German and German, my French is rusty but usable, and Italian basic, ideally an implementation would allow me to select {gsw, de, fr} as my preferred list of languages, skipping Italian because my comprehension is not good enough for arbitrary content.

Language Matching can also be used to get fallback data elements. In many cases, there may not be full data for a particular locale. For example, for a Breton speaker, the best fallback if data is unavailable might be French. That is, suppose we have found a Breton bundle, but it does not contain translation for the key "CN" (for the country China). It is best to return "chine", rather than falling back to the value default language such as Russian and getting "Кітай".  The language matching data can be used to get the closest fallback locales (of those supported) to a given language.

When such fallback is used for resource item lookup, the normal order of inheritance is used for resource item lookup, except that before using any data from root, the data for the fallback locales would be used if available. Language matching does not interact with the fallback of resources within the locale-parent chain. For example, suppose that we are looking for the value for a particular path P in nb-NO. In the absence of aliases, normally the following lookup is used.

nb-NOnbroot

That is, we first look in nb-NO. If there is no value for P there, then we look in nb. If there is no value for P there, we return the value for P in root (or a code value, if there is nothing there). Remember that if there is an alias element along this path, then the lookup may restart with a different path in nb-NO (or another locale).

However, suppose that nb-NO has the fallback values [nn da sv en], derived from language matching. In that case, an implementation may progressively lookup each of the listed locales, with the appropriate substitutions, returning the first value that is not found in root. This follows roughly the following pseudocode:

The locales in the fallback list are not used recursively. For example, for the lookup of a path in nb-NO, if fr were a fallback value for da, it would not matter for the above process. Only the original language matters.

 

The languageMatching data is interpreted as an ordered list. To find the match between any two languages, use the likely subtags to maximize each language, and perform the following steps.

  1. Remove any trailing fields that are the same.
  2. Traverse the list until a match is found. (If the oneway flag is false, then the match is symmetric.)
  3. Record the match value.
  4. Remove the final field from each, and if any fields are left, repeat these steps.

The end result is the product of the matched values.

There is one special case. Suppose we have the following situation:

Part of this is because 'und' has a special function in BCP47; it stands in for 'no supplied base language'. To prevent this from happening, if the desired base language is und, the language matcher should not apply likely subtags to it. 

Examples:

For example, suppose that nn-DE and nb-FR are being compared. They are first maximized to nn-Latn-DE and nb-Latn-FR, respectively. The list is searched. The first match is with "*-*-*", for a match of 96%. The languages are truncated to nn-Latn and nb-Latn, then to nn and nb. The first match is also for a value of 96%, so the result is 92%.

Note that language matching is orthogonal to the how closely two languages are related linguistically. For example, Breton is more closely related to Welsh than to French, but French is the better match (because it is more likely that a Breton reader will understand French than Welsh). This also illustrates that the matches are often asymmetric: it is not likely that a French reader will understand Breton.

The "*" acts as a wild card, as shown in the following example:

<languageMatch desired="es-*-ES" supported="es-*-ES" percent="100"/>
<!-- Latin American Spanishes are closer to each other. Approximate by having es-ES be further from everything else.-->

 

<languageMatch desired="es-*-ES" supported="es-*-*" percent="93"/>


<languageMatch desired="*" supported="*" percent="1"/>
<!-- [Default value - must be at end!] Normally there is no comprehension of different languages.-->


<languageMatch desired="*-*" supported="*-*" percent="20"/>
<!-- [Default value - must be at end!] Normally there is little comprehension of different scripts.-->


<languageMatch desired="*-*-*" supported="*-*-*" percent="96"/>
<!-- [Default value - must be at end!] Normally there are small differences across regions.-->

 

5 XML Format

There are two kinds of data that can be expressed in LDML: language-dependent data and supplementary data. In either case, data can be split across multiple files, which can be in multiple directory trees.

For example, the language-dependent data for Japanese in CLDR is present in the following files:

The status of the data is the same, whether or not data is split. That is, for the purpose of validation and lookup, all of the data for the above ja.xml files is treated as if it was in a single file.

Supplemental data relating to Japan or the Japanese writing system can be found in:

The following sections describe the structure of the XML format for language-dependent data. The more precise syntax is in the DTD, listed at the top of this document; however, the DTD does not describe all the constraints on the structure.

To start with, the root element is <ldml>, with the following DTD entry:

<!ELEMENT ldml (identity, (alias |(fallback*, localeDisplayNames?, layout?, contextTransforms?, characters?, delimiters?, measurement?, dates?, numbers?, units?, listPatterns?, collations?, posix?, segmentations?, rbnf?, metadata?, references?, special*))) >

The XML structure is stable over releases. Elements and attributes may be deprecated: they are retained in the DTD but their usage is strongly discouraged. In most cases, an alternate structure is provided for expressing the information.

In general, all translatable text in this format is in element contents, while attributes are reserved for types and non-translated information (such as numbers or dates). The reason that attributes are not used for translatable text is that spaces are not preserved, and we cannot predict where spaces may be significant in translated material.

There are two kinds of elements in LDML: rule elements and structure elements. For structure elements, there are restrictions to allow for effective inheritance and processing:

  1. There is no "mixed" content: if an element has textual content, then it cannot contain any elements.
  2. The [XPath] leading to the content is unique; no two different pieces of textual content have the same [XPath].

Rule elements do not have this restriction, but also do not inherit, except as an entire block. The structure elements are listed in serialElements in the supplemental metadata. See also Section 4.2 Inheritance and Validity. For more technical details, see Updating-DTDs.

Note that the data in examples given below is purely illustrative, and does not match any particular language. For a more detailed example of this format, see [Example]. There is also a DTD for this format, but remember that the DTD alone is not sufficient to understand the semantics, the constraints, nor  the interrelationships between the different elements and attributes. You may wish to have copies of each of these to hand as you proceed through the rest of this document.

In particular, all elements allow for draft versions to coexist in the file at the same time. Thus most elements are marked in the DTD as allowing multiple instances. However, unless an element is listed as a serialElement, or has a distinguishing attribute, it can only occur once as a subelement of a given element. Thus, for example, the following is illegal even though allowed by the DTD:

<languages>
  <language type="aa">...</language>
  <language type="aa">..</language>

There must be only one instance of these per parent, unless there are other distinguishing attributes (such as an alt element).

In general, LDML data should be in NFC format. However, certain elements may need to contain characters that are not in NFC, including exemplars, transforms, segmentations, and p/s/t/i/pc/sc/tc/ic rules in collation. These elements must not be normalized (either to NFC or NFD), or their meaning may be changed. Thus LDML documents must not be normalized as a whole. To prevent problems with normalization, no element value can start with a combining slash (U+0338 COMBINING LONG SOLIDUS OVERLAY).

Lists, such as singleCountries are space-delimited. That means that they are separated by one or more XML whitespace characters,

5.1 Common Elements

At any level in any element, two special elements are allowed.

5.1.1 Element special

This element is designed to allow for arbitrary additional annotation and data that is product-specific. It has one required attribute xmlns, which specifies the XML namespace of the special data. For example, the following used the version 1.0 POSIX special element.

<!DOCTYPE ldml SYSTEM "http://unicode.org/cldr/dtd/1.0/ldml.dtd" [
    <!ENTITY % posix SYSTEM "http://unicode.org/cldr/dtd/1.0/ldmlPOSIX.dtd">
%posix;
]>
<ldml>
...
<special xmlns:posix="http://www.opengroup.org/regproducts/xu.htm">
        <!-- old abbreviations for pre-GUI days -->
        <posix:messages>
            <posix:yesstr>Yes</posix:yesstr>
            <posix:nostr>No</posix:nostr>
            <posix:yesexpr>^[Yy].*</posix:yesexpr>
            <posix:noexpr>^[Nn].*</posix:noexpr>
        </posix:messages>
    </special>
</ldml>
5.1.1.1 Sample Special Elements

The elements in this section are not part of the Locale Data Markup Language 1.0 specification. Instead, they are special elements used for application-specific data to be stored in the Common Locale Repository. They may change or be removed future versions of this document, and are present her more as examples of how to extend the format. (Some of these items may move into a future version of the Locale Data Markup Language specification.)

The above examples are old versions: consult the documentation for the specific application to see which should be used.

These DTDs use namespaces and the special element. To include one or more, use the following pattern to import the special DTDs that are used in the file:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE ldml SYSTEM "http://unicode.org/cldr/dtd/1.1/ldml.dtd" [
    <!ENTITY % icu SYSTEM "http://unicode.org/cldr/dtd/1.1/ldmlICU.dtd">
    <!ENTITY % openOffice SYSTEM "http://unicode.org/cldr/dtd/1.1/ldmlOpenOffice.dtd">
%icu;
%openOffice;
]>

Thus to include just the ICU DTD, one uses:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE ldml SYSTEM "http://unicode.org/cldr/dtd/1.1/ldml.dtd" [
    <!ENTITY % icu SYSTEM "http://unicode.org/cldr/dtd/1.1/ldmlICU.dtd">
%icu;
]>

Note: A previous version of this document contained a special element for ISO TR 14652 compatibility data. That element has been withdrawn, pending further investigation, since 14652 is a Type 1 TR: "when the required support cannot be obtained for the publication of an International Standard, despite repeated effort". See the ballot comments on 14652 Comments for details on the 14652 defects. For example, most of these patterns make little provision for substantial changes in format when elements are empty, so are not particularly useful in practice. Compare, for example, the mail-merge capabilities of production software such as Microsoft Word or OpenOffice.

Note: While the CLDR specification guarantees backwards compatibility, the definition of specials is up to other organizations. Any assurance of backwards compatibility is up to those organizations.

A number of the elements above can have extra information for openoffice.org, such as the following example:

    <special xmlns:openOffice="http://www.openoffice.org">
        <openOffice:search>
            <openOffice:searchOptions>
                <openOffice:transliterationModules>IGNORE_CASE</openOffice:transliterationModules>
            </openOffice:searchOptions>
        </openOffice:search>
    </special>

5.1.2 Element alias

<!ELEMENT alias (special*) >
<!ATTLIST alias source NMTOKEN #REQUIRED >
<!ATTLIST alias path CDATA #IMPLIED>

The contents of any element in root can be replaced by an alias, which points to the path where the data can be found.

Aliases will only ever appear in root with the form //ldml/.../alias[@source="locale"][@path="..."].

Consider the following example in root:

      <calendar type="gregorian">
<months>
<default choice="format"/>
<monthContext type="format">
<default choice="wide"/>
<monthWidth type="abbreviated">
<alias source="locale" path="../monthWidth[@type='wide']"/>
</monthWidth>

If the locale "de_DE" is being accessed for a month name for format/abbreviated, then a resource bundle at "de_DE" will be searched for a resource element at the that path. If not found there, then the resource bundle at "de" will be searched, and so on. When the alias is found in root, then the search is restarted, but searching for format/wide element instead of format/abbreviated.

If the path attribute is present, then its value is an [XPath] that points to a different node in the tree. For example:

<alias source="locale" path="../monthWidth[@type='wide']"/>

The default value if the path is not present is the same position in the tree. All of the attributes in the [XPath] must be distinguishing elements. For more details, see Section 4.2 Inheritance and Validity.

There is a special value for the source attribute, the constant source="locale". This special value is equivalent to the locale being resolved. For example, consider the following example, where locale data for 'de' is being resolved:

Inheritance with source="locale"
Root de Resolved
<x>
  <a>1</a>
  <b>2</b>
  <c>3</c>

</x>
<x>
 <a>11</a>
 <b>12</b>

 <d>14</d>
</x>
<x>
 <a>11</a>
 <b>12</b>
 <c>3</c>
 <d>14</d>
</x>
<y>
 <alias source="locale" path="../x">
</y>
<y>

 <b>22</b>


 <e>25</e>
</y>
<y>
 <a>11</a>
 <b>22</b>
 <c>3</c>
 <d>14</d>
 <e>25</e>
</y>

The first row shows the inheritance within the <x> element, whereby <c> is inherited from root. The second shows the inheritance within the <y> element, whereby <a>, <c>, and <d> are inherited also from root, but from an alias there. The alias in root is logically replaced not by the elements in root itself, but by elements in the 'target' locale.

For more details on data resolution, see Section 4.2 Inheritance and Validity.

Aliases must be resolved recursively. An alias may point to another path that results in another alias being found, and so on. For example, looking up Thai buddhist abbreviated months for the locale xx-YY may result in the following chain of aliases being followed:

../../calendar[@type="buddhist"]/months/monthContext[@type="format"]/monthWidth[@type="abbreviated"]

xx-YY → xx → root // finds alias that changes path to:

../../calendar[@type="gregorian"]/months/monthContext[@type="format"]/monthWidth[@type="abbreviated"]

xx-YY → xx → root // finds alias that changes path to:

../../calendar[@type="gregorian"]/months/monthContext[@type="format"]/monthWidth[@type="wide"]

xx-YY → xx // finds value here

It is an error to have a circular chain of aliases. That is, a collection of LDML XML documents must not have situations where a sequence of alias lookups (including inheritance and multiple inheritance) can be followed indefinitely without terminating.

5.1.3 Element displayName

Many elements can have a display name. This is a translated name that can be presented to users when discussing the particular service. For example, a number format, used to format numbers using the conventions of that locale, can have translated name for presentation in GUIs.

  <numberFormat>
    <displayName>Prozentformat</displayName>
...
  <numberFormat>

Where present, the display names must be unique; that is, two distinct code would not get the same display name.  (There is one exception to this: in time zones, where parsing results would give the same GMT offset, the standard and daylight display names can be the same across different time zone IDs.) Any translations should follow customary practice for the locale in question. For more information, see [Data Formats].

5.1.4 Element cp

Unfortunately, XML does not have the capability to contain all Unicode code points. Due to this, in certain instances extra syntax is required to represent those code points that cannot be otherwise represented in element content. These escapes are only allowed in certain elements, according to the DTD.

Escaping Characters
Code Point XML Example
U+0000 <cp hex="0">

5.2 Common Attributes

5.2.1 Attribute type

The attribute type is also used to indicate an alternate resource that can be selected with a matching type=option in the locale id modifiers, or be referenced by a default element. For example:

<ldml>
  ...
  <currencies>
    <currency>...</currency>
    <currency type="preEuro">...</currency>
  </currencies>
</ldml>

5.2.2 Attribute draft

If this attribute is present, it indicates the status of all the data in this element and any subelements (unless they have a contrary draft value), as per the following:

For more information on precisely how these values are computed for any given release, see Data Submission and Vetting Process on the CLDR website.

Normally draft attributes should only occur on "leaf" elements. For a more formal description of how elements are inherited, and what their draft status is, see Section 4.2 Inheritance and Validity.

5.2.3 Attribute alt

This attribute labels an alternative value for an element. The value is a descriptor indicates what kind of alternative it is, and takes one of the following

"proposed" should only be present if the draft status is not "approved". It indicates that the data is proposed replacement data that has been added provisionally until the differences between it and the other data can be vetted. For example, suppose that the translation for September for some language is "Settembru", and a bug report is filed that that should be "Settembro". The new data can be entered in, but marked as alt="proposed" until it is vetted.

...
<month type="9">Settembru</month>
<month type="9" draft="unconfirmed" alt="proposed">Settembro</month>
<month type="10">...

Now assume another bug report comes in, saying that the correct form is actually "Settembre". Another alternative can be added:

...
<month type="9" draft="unconfirmed" alt="proposed2">Settembre</month>
...

The values for variantname at this time include "variant", "list", "email", "www", "short", and "secondary".

Attribute validSubLocales

The attribute validSubLocales allows sublocales in a given tree to be treated as though a file for them were present when there is not one. It can be applied to any element. It only has an effect for locales that inherit from the current file where a file is missing, and the elements would not otherwise be draft.

For a more complete description of how draft applies to data, see Section 4.2 Inheritance and Validity.

Attribute references

The value of this attribute is a token representing a reference for the information in the element, including standards that it may conform to. <references>. (In older versions of CLDR, the value of the attribute was freeform text. That format is deprecated.)

Example:

<territory type="UM" references="R222">USAs yttre öar</territory>

The reference element may be inherited. Thus, for example, R222 may be used in sv_SE.xml even though it is not defined there, if it is defined in sv.xml.

<... allow="verbatim" ...> (deprecated)

This attribute was originally intended for use in marking display names whose capitalization differed from what was indicated by the now-deprecated <inText> element (perhaps, for example, because the names included a proper noun). It was never supported in the dtd and is not needed for use with the new <contextTransforms> element.

5.3 Common Structures

5.3.1 Date and Date Ranges

When attribute specify date ranges, it is usually done with attributes from and to. The from attribute specifies the starting point, and the to attribute specifies the end point. The deprecated time attribute was formerly used to specify time with the deprecated weekEndStart and weekEndEnd elements, which were themselves inherently from or to.

The data format is a restricted ISO 8601 format, restricted to the fields year, month, day, hour, minute, and second in that order, with "-" used as a separator between date fields, a space used as the separator between the date and the time fields, and ":" used as a separator between the time fields. If the minute or minute and second are absent, they are interpreted as zero. If the hour is also missing, then it is interpreted based on whether the attribute is from or to.

That is, Friday at 24:00:00 is the same time as Saturday at 00:00:00. Thus when the hour is missing, the from and to are interpreted inclusively: the range includes all of the day mentioned.

For example, the following are equivalent:

<usesMetazone from="1991-10-27" to="2006-04-02" .../>
<usesMetazone from="1991-10-27 00:00:00" to="2006-04-02 24:00:00" .../>
<usesMetazone from="1991-10-26 24:00:00" to="2006-04-03 00:00:00" .../>

If the from element is missing, it is assumed to be as far backwards in time as there is data for; if the to element is missing, then it is from this point onwards, with no known end point.

The dates and times are specified in local time, unless otherwise noted. (In particular, the metazone values are in UTC (also known as GMT).

5.3.2 Text Directionality

The content of certain elements, such as date or number formats, may consist of several sub-elements with an inherent order (for example, the year, month, and day for dates). In some cases, the order of these sub-elements may be changed depending on the bidirectional context in which the element is embedded.

For example, short date formats in languages such as Arabic may contain neutral or weak characters at the beginning or end of the element content. In such a case, the overall order of the sub-elements may change depending on the surrounding text.

Element content whose display may be affected in this way should include an explicit direction mark, such as U+200E LEFT-TO-RIGHT MARK or U+200F RIGHT-TO-LEFT MARK, at the beginning or end of the element content, or both.


		

5.3.3 Unicode Sets

Some attribute values or element contents use UnicodeSet notation. A UnicodeSet represents a set of Unicode characters (and possibly strings) determined by a pattern, following UTS #18: Unicode Regular Expressions [UTS18], Level 1 and RL2.5, including the syntax where given. For an example of a concrete implementation of this, see [ICUUnicodeSet].

Patterns are a series of characters bounded by square brackets that contain lists of characters and Unicode property sets. Lists are a sequence of characters that may have ranges indicated by a '-' between two characters, as in "a-z". The sequence specifies the range of all characters from the left to the right, in Unicode order. For example, [a c d-f m] is equivalent to [a c d e f m]. Whitespace can be freely used for clarity, as [a c d-f m] means the same as [acd-fm].

Unicode property sets are specified by any Unicode property and a value of that property, such as [:General_Category=Letter:]. The property names are defined by the PropertyAliases.txt file and the property values by the PropertyValueAliases.txt file. For more information, see [UAX44]. The syntax for specifying the property sets is an extension of either POSIX or Perl syntax, by the addition of "=<value>". For example, you can match letters by using the POSIX-style syntax:

[:General_Category=Letter:]

or by using the Perl-style syntax

\p{General_Category=Letter}.

Property names and values are case-insensitive, and whitespace, "-", and "_" are ignored. The property name can be omitted for the Category and Script properties, but is required for other properties. If the property value is omitted, it is assumed to represent a boolean property with the value "true". Thus [:Letter:] is equivalent to [:General_Category=Letter:], and [:Wh-ite-s pa_ce:] is equivalent to [:Whitespace=true:].

The table below shows the two kinds of syntax: POSIX and Perl style. Also, the table shows the "Negative", which is a property that excludes all characters of a given kind. For example, [:^Letter:] matches all characters that are not [:Letter:].

  Positive Negative
POSIX-style Syntax [:type=value:] [:^type=value:]
Perl-style Syntax \p{type=value} \P{type=value}

These following low-level lists or properties then can be freely combined with the normal set operations (union, inverse, difference, and intersection):

The binary operators '&', '-', and the implicit union have equal precedence and bind left-to-right. Thus [[:letter:]-[a-z]-[\u0100-\u01FF]] is equal to [[[:letter:]-[a-z]]-[\u0100-\u01FF]]. Another example is the set [[ace][bdf] - [abc][def]], which is not the empty set, but instead equal to [[[[ace] [bdf]] - [abc]] [def]], which equals [[[abcdef] - [abc]] [def]], which equals [[def] [def]], which equals [def].

One caution: the '&' and '-' operators operate between sets. That is, they must be immediately preceded and immediately followed by a set. For example, the pattern [[:Lu:]-A] is illegal, since it is interpreted as the set [:Lu:] followed by the incomplete range -A. To specify the set of upper case letters except for 'A', enclose the 'A' in a set: [[:Lu:]-[A]].

A multi-character string can be in a Unicode set, to represent a tailored grapheme cluster for a particular language. The syntax uses curly braces for that case.

In Unicode Sets, there are two ways to quote syntax characters and whitespace:

5.3.3.1 Single Quote

Two single quotes represents a single quote, either inside or outside single quotes. Text within single quotes is not interpreted in any way (except for two adjacent single quotes). It is taken as literal text (special characters become non-special).

5.3.3.2 Backslash Escapes

Outside of single quotes, certain backslashed characters have special meaning:

\uhhhh Exactly 4 hex digits; h in [0-9A-Fa-f]
\Uhhhhhhhh Exactly 8 hex digits
\xhh 1-2 hex digits
\ooo 1-3 octal digits; o in [0-7] 
\a U+0007 (BELL)
\b U+0008 (BACKSPACE)
\t U+0009 (HORIZONTAL TAB)
\n U+000A (LINE FEED)
\v U+000B (VERTICAL TAB)
\f U+000C (FORM FEED)
\r U+000D (CARRIAGE RETURN)
\\ U+005C (BACKSLASH)
\N{name} The Unicode character named "name".

Anything else following a backslash is mapped to itself, except in an environment where it is defined to have some special meaning. For example, \p{uppercase} is the set of upper case letters in Unicode.

Any character formed as the result of a backslash escape loses any special meaning and is treated as a literal. In particular, note that \u and \U escapes create literal characters. (In contrast, Java treats Unicode escapes as just a way to represent arbitrary characters in an ASCII source file, and any resulting characters are not tagged as literals.)

The following table summarizes the syntax that can be used.

Example Description
[a] The set containing 'a' alone
[a-z] The set containing 'a' through 'z' and all letters in between, in Unicode order.
Thus it is the same as [\u0061-\u007A].
[^a-z] The set containing all characters but 'a' through 'z'.
Thus it is the same as [\u0000-\u0061 \u007B..\U0010FFFF].
[[pat1][pat2]] The union of sets specified by pat1 and pat2
[[pat1]&[pat2]] The intersection of sets specified by pat1 and pat2
[[pat1]-[pat2]] The asymmetric difference of sets specified by pat1 and pat2
[a {ab} {ac}] The character 'a' and the multi-character strings "ab" and "ac"
[:Lu:] The set of characters with a given property value, as defined by PropertyValueAliases.txt. In this case, these are the Unicode upper case letters. The long form for this is [:General_Category=Uppercase_Letter:].
[:L:] The set of characters belonging to all Unicode categories starting with 'L', that is, [[:Lu:][:Ll:][:Lt:][:Lm:][:Lo:]]. The long form for this is [:General_Category=Letter:].

5.4 Identity Elements

<!ELEMENT identity (alias | (version, generation?, language, script?, territory?, variant?, special*) ) >

The identity element contains information identifying the target locale for this data, and general information about the version of this data.

<version number="$Revision: 1.227 $">

The version element provides, in an attribute, the version of this file.  The contents of the element can contain textual notes about the changes between this version and the last. For example:

<version number="1.1">Various notes and changes in version 1.1</version>

This is not to be confused with the version attribute on the ldml element, which tracks the dtd version.

<generation date="$Date: 2007/07/17 23:41:16 $" />

The generation element contains the last modified date for the data. This can be in two formats: ISO 8601 format, or CVS format (illustrated by the example above).

<language type="en"/>

The language code is the primary part of the specification of the locale id, with values as described above.

<script type="Latn" />

The script code may be used in the identification of written languages, with values described above.

<territory type="US"/>

The territory code is a common part of the specification of the locale id, with values as described above.

<variant type="NYNORSK"/>

The variant code is the tertiary part of the specification of the locale id, with values as described above.

When combined according to the rules described in Section 3, Unicode Language and Locale Identifiers, the language element, along with any of the optional script, territory, and variant elements, must identify a known, stable locale identifier. Otherwise, it is an error.

5.5 Valid Attribute Values

The valid attribute values, as well as other validity information is contained in the supplementalMetadata.xml file. (Some, but not all, of this information could have been represented in XML Schema or a DTD.) Most of this is primarily for internal tool use.

The following specify the ordering of elements / attributes in the file:

<elementOrder>ldml alternate attributeOrder attributes blockingItems calendarPreference ...</elementOrder>
<attributeOrder>_q access after aliases allowsParsing alpha3 alternate at attribute ...</attributeOrder>

The suppress elements are those that are suppressed in canonicalization.

The serialElements are those that do not inherit, and may have ordering

<serialElements>attributeValues base comment extend first_non_ignorable first_primary_ignorable
first_secondary_ignorable first_tertiary_ignorable first_trailing first_variable i ic languagePopulation
last_non_ignorable last_primary_ignorable last_secondary_ignorable last_tertiary_ignorable last_trailing
last_variable optimize p pc reset rules s sc settings suppress_contractions t tRule tc variable x
</serialElements>

The validity elements give the possible attribute values. They are in the format of a series of variables, followed by attributeValues.

<variable id="$calendar" type="choice">
buddhist coptic ethiopic ethiopic-amete-alem chinese gregorian hebrew indian islamic islamic-civil
japanese arabic civil-arabic thai-buddhist persian roc</variable>

The types indicate the style of match:

If the attribute order="given" is supplied, it indicates the order of elements when canonicalizing (see below).

The variable values are intended for internal testing, and the definition and usage may change between releases. They do not necessarily include all valid elements. For example, for primary language codes, they include the subset that occur in CLDR locale data. They are intended for a particular version of CLDR, and may omit codes that were present in earlier versions, such as deprecated codes.

The <deprecated> element lists elements, attributes, and attribute values that are deprecated. If any deprecatedItems element contains more than one attribute, then only the listed combinations are deprecated. Thus the following means not that the draft attribute is deprecated, but that the true and false values for that attribute are:

<deprecatedItems attributes="draft" values="true false"/> 

Similarly, the following means that the type attribute is deprecated, but only for the listed elements:

<deprecatedItems elements="abbreviationFallback default ... preferenceOrdering" attributes="type"/> 

<!ELEMENT blockingItems EMPTY >
<!ATTLIST blockingItems elements NMTOKENS #IMPLIED >

The blockingItems indicate which elements (and their child elements) do not inherit. For example, because supplementalData is a blocking item, all paths containing the element supplementalData do not inherit.

<!ELEMENT distinguishingItems EMPTY >
<!ATTLIST distinguishingItems exclude ( true | false ) #IMPLIED >
<!ATTLIST distinguishingItems elements NMTOKENS #IMPLIED >
<!ATTLIST distinguishingItems attributes NMTOKENS #IMPLIED >

The distinguishing items indicate which combinations of elements and attributes (in unblocked environments) are distinguishing in performing inheritance. For example, the attribute type is distinguishing except in combination with certain elements, such as in:

<distinguishingItems
  exclude="true"
  elements="default measurementSystem mapping abbreviationFallback preferenceOrdering" 
  attributes="type"/>

5.6 Canonical Form

The following are restrictions on the format of LDML files to allow for easier parsing and comparison of files.

Peer elements have consistent order. That is, if the DTD or this specification requires the following order in an element foo:

<foo>
  <pattern>
  <somethingElse>
</foo>

It can never require the reverse order in a different element bar.

<foo>
  <somethingElse>
  <pattern>
</foo>

Note that there was one case that had to be corrected in order to make this true. For that reason, pattern occurs twice under currency:

<!ELEMENT currency (alias | (pattern*, displayName?, symbol?, pattern*,
decimal?, group?, special*)) >

XML files can have a wide variation in textual form, while representing precisely the same data. By putting the LDML files in the repository into a canonical form, this allows us to use the simple diff tools used widely (and in CVS) to detect differences when vetting changes, without those tools being confused. This is not a requirement on other uses of LDML; just simply a way to manage repository data more easily.

5.6.1 Content

  1. All start elements are on their own line, indented by depth tabs.
  2. All end elements (except for leaf nodes) are on their own line, indented by depth tabs.
  3. Any leaf node with empty content is in the form <foo/>.
  4. There are no blank lines except within comments or content.
  5. Spaces are used within a start element. There are no extra spaces within elements.
    • <version number="1.2"/>, not <version  number = "1.2" />
    • </identity>, not </identity >
  6. All attribute values use double quote ("), not single (').
  7. There are no CDATA sections, and no escapes except those absolutely required.
    • no &apos; since it is not necessary
    • no '&#x61;', it would be just 'a'
  8. All attributes with defaulted values are suppressed. See Section 5.6.8 Defaulted Values Table.
  9. The draft and alt="proposed.*" attributes are only on leaf elements.
  10. The tzid are canonicalized in the following way:
    1. All tzids as of as CLDR 1.1 (2004.06.08) in zone.tab are canonical.
    2. After that point, the first time a tzid is introduced, that is the canonical form.

    That is, new IDs are added, but existing ones keep the original form. The TZ timezone database keeps a set of equivalences in the "backward" file. These are used to map other tzids to the canonical form. For example, when America/Argentina/Catamarca was introduced as the new name for the previous America/Catamarca , a link was added in the backward file.

    Link America/Argentina/Catamarca America/Catamarca

Example:

<ldml draft="unconfirmed" >
	<identity>
		<version number="1.2"/>
		<generation date="2004-06-04"/>
		<language type="en"/>
		<territory type="AS"/>
	</identity>
	<numbers>
		<currencyFormats>
			<currencyFormatLength>
				<currencyFormat>
					<pattern>¤#,##0.00;(¤#,##0.00)</pattern>
				</currencyFormat>
			</currencyFormatLength>
		</currencyFormats>
	</numbers>
</ldml>

5.6.2 Ordering

An element is ordered first by the element name, and then if the element names are identical, by the sorted set of attribute-value pairs. For the latter, compare the first pair in each (in sorted order by attribute pair). If not identical, go to the second pair, and so on.

Elements and attributes are ordered according to their order in the respective DTDs. Attribute value comparison is a bit more complicated, and may depend on the attribute and type. This is currently done with specific ordering tables.

Any future additions to the DTD must be structured so as to allow compatibility with this ordering. See also Section 5.5 Valid Attribute Values.

5.6.3 Comments

  1. Comments are of the form <!-- stuff -->.
  2. They are logically attached to a node. There are 4 kinds:
    1. Inline always appear after a leaf node, on the same line at the end. These are a single line.
    2. Preblock comments always precede the attachment node, and are indented on the same level.
    3. Postblock comments always follow the attachment node, and are indented on the same level.
    4. Final comment, after </ldml>
  3. Multiline comments (except the final comment) have each line after the first indented to one deeper level.

Examples:

<eraAbbr>
	<era type="0">BC</era> <!-- might add alternate BDE in the future -->
...
<timeZoneNames>
	<!-- Note: zones that do not use daylight time need further work --> 
	<zone type="America/Los_Angeles">
	...
	<!-- Note: the following is known to be sparse,
		and needs to be improved in the future -->
	<zone type="Asia/Jerusalem">

6 Property Data

Some data in CLDR does not use an XML format, but rather a semicolon-delimited format derived from that of the Unicode Character Database. That is because the data is more likely to be parsed by implementations that already parse UCD data. Those files are present in the common/properties directory.

Each file has a header that explains the format and usage of the data.

7 Lenient Parsing

7.1 Motivation

User input is frequently messy. Attempting to parse it by matching it exactly against a pattern is likely to be unsuccessful, even when the meaning of the input is clear to a human being. For example, for a date pattern of "MM/dd/yy", the input "June 1, 2006" will fail.

The goal of lenient parsing is to accept user input whenever it is possible to decipher what the user intended. Doing so requires using patterns as data to guide the parsing process, rather than an exact template that must be matched. This informative section suggests some heuristics that may be useful for lenient parsing of dates, times, and numbers.

7.2 Loose Matching

Loose matching ignores attributes of the strings being compared that are not important to matching. It involves the following steps:

Loose matching involves (logically) applying the above transform to both the input text and to each of the field elements used in matching, before applying the specific heuristics below. For example, if the input number text is " - NA f. 1,000.00", then it is mapped to "-naf1,000.00" before processing. The currency signs are also transformed, so "NA f." is converted to "naf" for purposes of matching. As with other Unicode algorithms, this is a logical statement of the process; actual implementations can optimize, such as by applying the transform incrementally during matching.

8 Deprecated Structure

The following structure was present in previous versions of CLDR. While valid LDML, it is discouraged, and no longer used in CLDR.

8.1 Element fallback

<!ELEMENT fallback (#PCDATA) >

The fallback element is deprecated. Implementations should use instead the information in Section 4.4 Language Matching for doing language fallback.

8.2 BCP 47 Keyword Mapping

Note: This structure is deprecated and replaced with Section 3.7 Unicode BCP 47 Extension Data.

<!ELEMENT bcp47KeywordMappings ( mapKeys?, mapTypes* ) >
<!ELEMENT mapKeys ( keyMap* ) >
<!ELEMENT keyMap EMPTY >
<!ATTLIST keyMap type NMTOKEN #REQUIRED >
<!ATTLIST keyMap bcp47 NMTOKEN #REQUIRED >
<!ELEMENT mapTypes ( typeMap* ) >
<!ATTLIST mapTypes type NMTOKEN #REQUIRED >
<!ELEMENT typeMap EMPTY >
<!ATTLIST typeMap type CDATA #REQUIRED >
<!ATTLIST typeMap bcp47 NMTOKEN #REQUIRED >

This section defines mappings between old Unicode locale identifier key/type values and their BCP 47 'u' extension subtag representations. The 'u' extension syntax described in Section 3.7 Unicode BCP 47 Extension Data restricts a key to two ASCII alphanumerics and a type to three to eight ASCII alphanumerics. A key or a type which does not meet that syntax requirement is converted according to the mapping data defined by the mapKeys or mapTypes elements. For example, a keyword "collation=phonebook" is converted to BCP 47 'u' extension subtags "co-phonebk" by the mapping data below:

    <mapKeys>
        ...
        <keyMap type="collation" bcp47="co"/>
        ...
    </mapKeys>
    <mapTypes type="collation">
        ...
        <typeMap type="phonebook" bcp47="phonebk"/>
        ...
    </mapTypes>
	

8.3 Choice Patterns

Note: This structure is deprecated and replaced with count attributes.

A choice pattern is a string that chooses among a number of strings, based on numeric value. It has the following form:

<choice_pattern> = <choice> ( '|' <choice> )*
<choice> = <number><relation><string>
<number> = ('+' | '-')? ('∞' | [0-9]+ ('.' [0-9]+)?)
<relation> = '<' | '
≤'

The interpretation of a choice pattern is that given a number N, the pattern is scanned from right to left, for each choice evaluating <number> <relation> N. The first choice that matches results in the corresponding string. If no match is found, then the first string is used. For example:

Pattern N Result
0≤Rf|1≤Ru|1<Re -∞, -3, -1, -0.000001 Rf (defaulted to first string)
0, 0.01, 0.9999 Rf
1 Ru
1.00001, 5, 99, Re

Quoting is done using ' characters, as in date or number formats.

8.4 Element default

Note: This structure is deprecated. Use replacement structure instead, for example:

In some cases, a number of elements are present. The default element can be used to indicate which of them is the default, in the absence of other information. The value of the choice attribute is to match the value of the type attribute for the selected item.

<timeFormats>
  <default choice="medium" /> 
  <timeFormatLength type="full">
    <timeFormat type="standard">
      <pattern type="standard">h:mm:ss a z</pattern> 
    </timeFormat>
  </timeFormatLength>
  <timeFormatLength type="long">
    <timeFormat type="standard">
      <pattern type="standard">h:mm:ss a z</pattern> 
    </timeFormat>
  </timeFormatLength>
  <timeFormatLength type="medium">
    <timeFormat type="standard">
      <pattern type="standard">h:mm:ss a</pattern> 
    </timeFormat>
  </timeFormatLength>
...

Like all other elements, the <default> element is inherited. Thus, it can also refer to inherited resources. For example, suppose that the above resources are present in fr, and that in fr_BE we have the following:

<timeFormats>
  <default choice="long"/>
</timeFormats>

In that case, the default time format for fr_BE would be the inherited "long" resource from fr. Now suppose that we had in fr_CA:

  <timeFormatLength type="medium">
    <timeFormat type="standard">
      <pattern type="standard">...</pattern> 
    </timeFormat>
  </timeFormatLength>
    

In this case, the <default> is inherited from fr, and has the value "medium". It thus refers to this new "medium" pattern in this resource bundle.

8.5 Attribute standard

Note: This attribute is deprecated. Instead, use a reference element with the attribute standard="true".

The value of this attribute is a list of strings representing standards: international, national, organization, or vendor standards. The presence of this attribute indicates that the data in this element is compliant with the indicated standards. Where possible, for uniqueness, the string should be a URL that represents that standard. The strings are separated by commas; leading or trailing spaces on each string are not significant. Examples:

<collation standard="MSA 200:2002">
...
<dateFormatStyle standard=”http://www.iso.ch/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=26780&amp;ICS1=1&amp;ICS2=140&amp;ICS3=30”>

 

8.6 Element base

Note: This element is deprecated. Use the collation <import> element instead.

The optional base element <base>...</base> , contains an alias element that points to another data source that defines a base collation. If present, it indicates that the settings and rules in the collation are modifications applied on top of the respective elements in the base collation. That is, any successive settings, where present, override what is in the base as described in Setting Options. Any successive rules are concatenated to the end of the rules in the base. The results of multiple rules applying to the same characters is covered in Orderings.

8.7 Element rules

Note: The XML collation syntax is deprecated; this includes the <rules> element and its subelements, except that the <import> element has been moved up to be a subelement of <collation>. Use the basic collation syntax with the <cr> element instead.

<!ELEMENT rules (alias | ( ( reset | import ), ( reset | import | p | pc | s | sc | t | tc | i | ic | x)* )) >

8.8 Deprecated subelements of <dates>

8.9 Deprecated subelements of <calendars>

8.10 Deprecated subelements of <timeZoneNames>

8.11 Deprecated subelements of <zone> and <metazone>

8.12 Renamed attribute values for <contextTransformUsage> element

The <contextTransformUsage> element was introduced in CLDR 21. The values for its type attribute are documented in <contextTransformUsage> type attribute values. In CLDR 25, some of these values were renamed from their previous values for improved clarity:


9 Links to Other Parts

The LDML specification is split into several parts by topic, with one HTML document per part. The following tables provide redirects for links to specific topics. Please update your links and bookmarks.

Part 1: Core specification (this document): No redirects needed.

Part 2: General (display names & transforms, etc.)
Old section Section in new part
5.4 Display Name Elements 1 Display Name Elements
5.5 Layout Elements 2 Layout Elements
5.6 Character Elements 3 Character Elements
5.6.1 Exemplar Syntax 3.1 Exemplar Syntax
5.6.2 Restrictions 3.1 Exemplar Syntax
5.6.3 Mapping 3.2 Mapping
5.6.4 Index Labels 3.3 Index Labels
5.6.5 Ellipsis 3.4 Ellipsis
5.6.6 More Information 3.5 More Information
5.7 Delimiter Elements 4 Delimiter Elements
C.6 Measurement System Data 5 Measurement System Data
5.8 Measurement Elements (deprecated) 5.1 Measurement Elements (deprecated)
5.11 Unit Elements 6 Unit Elements
5.12 POSIX Elements 7 POSIX Elements
5.13 Reference Element 8 Reference Element
5.15 Segmentations 9 Segmentations
5.15.1 Segmentation Inheritance 9.1 Segmentation Inheritance
5.16 Transforms 10 Transforms
N Transform Rules 10.3 Transform Rules Syntax
5.18 List Patterns 11 List Patterns
C.20 Gender of Lists 11.1 Gender of Lists
5.19 ContextTransform Elements 12 ContextTransform Elements
Part 3: Numbers (number & currency formatting)
Old section Section in new part
C.13 Numbering Systems 1 Numbering Systems
5.10 Number Elements 2 Number Elements
5.10.1 Number Symbols 2.3 Number Symbols
G Number Format Patterns 3 Number Format Patterns
5.10.2 Currencies 4 Currencies
C.1 Supplemental Currency Data 4.1 Supplemental Currency Data
C.11 Language Plural Rules 5 Language Plural Rules
5.17 Rule-Based Number Formatting 6 Rule-Based Number Formatting
Part 4: Dates (date, time, time zone formatting)
Old section Section in new part
5.9 Date Elements 1 Overview: Dates Element, Supplemental Date and Calendar Information
5.9.1 Calendar Elements 2 Calendar Elements
<months>, <days>, <quarters>, <eras> 2.1 <months>, <days>, <quarters>, <eras>
<monthPatterns>, <cyclicNameSets> 2.2 <monthPatterns>, <cyclicNameSets>
<dayPeriods> 2.3 <dayPeriods>
<dateFormats> 2.4 <dateFormats>
<timeFormats> 2.5 <timeFormats>
<dateTimeFormats> 2.6 <dateTimeFormats>
5.9.2 Calendar Fields 3 Calendar Fields
5.9.3 Time Zone Names 5 Time Zone Names
C.5 Supplemental Calendar Data 4 Supplemental Calendar Data
C.7 Supplemental Time Zone Data 6 Supplemental Time Zone Data
C.15 Calendar Preference Data 4.2 Calendar Preference Data
C.17 DayPeriod Rules 4.5 Day Period Rules
Appendix F: Date Format Patterns 8 Date Format Patterns
Date Field Symbol Table Date Field Symbol Table
F.1 Localized Pattern Characters (deprecated) 8.1 Localized Pattern Characters (deprecated)
Appendix J: Time Zone Display Names 7 Using Time Zone Names
fallbackFormat: fallbackFormat:
O.4 Parsing Dates and Times 9 Parsing Dates and Times
Part 5: Collation (sorting, searching, grouping)
Old section Section in new part
5.14 Collation Elements 3 Collation Tailorings
5.14.1 Version 3.1 Version
5.14.2 Collation Element 3.2 Collation Element
5.14.3 Setting Options 3.3 Setting Options
Table Collation Settings Table Collation Settings
5.14.4 Collation Rule Syntax 3.4 Collation Rule Syntax
5.14.5 Orderings 3.5 Orderings
5.14.6 Contractions 3.6 Contractions
5.14.7 Expansions 3.7 Expansions
5.14.8 Context Before 3.8 Context Before
5.14.9 Placing Characters Before Others 3.9 Placing Characters Before Others
5.14.10 Logical Reset Positions 3.10 Logical Reset Positions
5.14.11 Special-Purpose Commands 3.11 Special-Purpose Commands
5.14.12 Collation Reordering 3.12 Collation Reordering
5.14.13 Case Parameters 3.13 Case Parameters
Definition: UncasedExceptions Definition: UncasedExceptions
Definition: LowerExceptions Definition: LowerExceptions
Definition: UpperExceptions Definition: UpperExceptions
5.14.14 Visibility 3.14 Visibility
Part 6: Related Information (supplemental data)
Old section Section in new part
C Supplemental Data Introduction Supplemental Data
C.2 Supplemental Territory Containment 1.1 Supplemental Territory Containment
C.4 Supplemental Territory Information 1.2 Supplemental Territory Information
C.3 Supplemental Language Data 2 Supplemental Language Data
C.9 Supplemental Code Mapping 4 Supplemental Code Mapping
C.12 Telephone Code Data 5 Telephone Code Data
C.14 Postal Code Validation 6 Postal Code Validation
C.8 Supplemental Character Fallback Data 7 Supplemental Character Fallback Data
M Coverage Levels 8 Coverage Levels
5.20 Metadata Elements 10 Locale Metadata Element
P Supplemental Metadata
P.1 Supplemental Alias Information
P.2 Supplemental Deprecated Information
P.3 Default Content
9 Supplemental Metadata
9.1 Supplemental Alias Information
9.2 Supplemental Deprecated Information
9.3 Default Content
Part 7: Keyboards (keyboard mappings)
Old section Section in new part
S Keyboards 1 Keyboards
S Goals and Nongoals Goals and Nongoals
S Definitions Definitions
S File and Directory Structure File and Directory Structure
S Element Hierarchy - Layout File Element Hierarchy - Layout File
S Element Hierarchy - Platform File Element Hierarchy - Platform File
S Invariants Invariants
S Data Sources Data Sources
S Keyboard IDs Keyboard IDs
S Platform Behaviors in Edge Cases Platform Behaviors in Edge Cases
S Element: keyboard Element: keyboard
S Element: version Element: version
S Element: generation Element: generation
S Element: names Element: names
S Element: name Element: name
S Element: settings Element: settings
S Element: keyMap Element: keyMap
S Element: map Element: map
S Element: transforms Element: transforms
S Element: transform Element: transform
S Element: platform Element: platform
S Element: hardwareMap Element: hardwareMap
S Element: map Element: map
S Principles for Keyboard Ids Principles for Keyboard Ids

References

Ancillary Information To properly localize, parse, and format data requires ancillary information, which is not expressed in Locale Data Markup Language. Some of the formats for values used in Locale Data Markup Language are constructed according to external specifications. The sources for this data and/or formats include the following:
 
[Bugs] CLDR Bug Reporting form
http://cldr.unicode.org/index/bug-reports
[Charts] The online code charts can be found at http://unicode.org/charts/ An index to character names with links to the corresponding chart is found at http://unicode.org/charts/charindex.html
[DUCET] The Default Unicode Collation Element Table (DUCET)
For the base-level collation, of which all the collation tables in this document are tailorings.
http://unicode.org/reports/tr10/#Default_Unicode_Collation_Element_Table
[FAQ] Unicode Frequently Asked Questions
http://unicode.org/faq/
For answers to common questions on technical issues.
[FCD] As defined in UTN #5 Canonical Equivalences in Applications
http://unicode.org/notes/tn5/
[Glossary] Unicode Glossary
http://unicode.org/glossary/
For explanations of terminology used in this and other documents.
[JavaChoice] Java ChoiceFormat
http://docs.oracle.com/javase/7/docs/api/java/text/ChoiceFormat.html
[Olson] The TZID Database (aka Olson timezone database)
Time zone and daylight savings information.
http://www.iana.org/time-zones
For archived data, see 
ftp://ftp.iana.org/tz/releases/
[Reports] Unicode Technical Reports
http://unicode.org/reports/
For information on the status and development process for technical reports, and for a list of technical reports.
[Unicode] The Unicode Consortium. The Unicode Standard, Version 6.2.0, (Mountain View, CA: The Unicode Consortium, 2012. ISBN 978-1-936213-07-8)
http://www.unicode.org/versions/Unicode6.2.0/
[Versions] Versions of the Unicode Standard
http://www.unicode.org/versions/
For information on version numbering, and citing and referencing the Unicode Standard, the Unicode Character Database, and Unicode Technical Reports.
[XPath] http://www.w3.org/TR/xpath/
Other Standards Various standards define codes that are used as keys or values in Locale Data Markup Language. These include:
[BCP47] http://www.rfc-editor.org/rfc/bcp/bcp47.txt

The Registry
http://www.iana.org/assignments/language-subtag-registry

[ISO639] ISO Language Codes
http://www.loc.gov/standards/iso639-2/
Actual List
http://www.loc.gov/standards/iso639-2/langcodes.html
[ISO1000] ISO 1000: SI units and recommendations for the use of their multiples and of certain other units, International Organization for Standardization, 1992.
http://www.iso.org/iso/catalogue_detail?csnumber=5448
[ISO3166] ISO Region Codes
http://www.iso.org/iso/country_codes
Actual List
http://www.iso.org/iso/country_names_and_code_elements
[ISO4217] ISO Currency Codes
http://www.iso.org/iso/home/standards/currency_codes.htm

(Note that as of this point, there are significant problems with this list. The supplemental data file contains the best compendium of currency information available.)

[ISO15924] ISO Script Codes
http://www.unicode.org/iso15924/standard/index.html
Actual List
http://www.unicode.org/iso15924/codelists.html
[LOCODE] United Nations Code for Trade and Transport Locations, commonly known as "UN/LOCODE"
http://www.unece.org/cefact/locode/welcome.html
Download at:  http://www.unece.org/cefact/codesfortrade/codes_index.htm
[RFC6067] BCP 47 Extension U
http://www.ietf.org/rfc/rfc6067.txt
[RFC6497] BCP 47 Extension T - Transformed Content
http://www.ietf.org/rfc/rfc6497.txt
[UNM49] UN M.49: UN Statistics Division

Country or area & region codes
http://unstats.un.org/unsd/methods/m49/m49.htm

Composition of macro geographical (continental) regions, geographical sub-regions, and selected economic and other groupings
http://unstats.un.org/unsd/methods/m49/m49regin.htm

[XML Schema] W3C XML Schema
http://www.w3.org/XML/Schema
General The following are general references from the text:
[ByType] CLDR Comparison Charts
http://www.unicode.org/cldr/comparison_charts.html
[Calendars] Calendrical Calculations: The Millennium Edition by Edward M. Reingold, Nachum Dershowitz; Cambridge University Press; Book and CD-ROM edition (July 1, 2001); ISBN: 0521777526. Note that the algorithms given in this book are copyrighted.
[Comparisons] Comparisons between locale data from different sources
http://unicode.org/cldr/data/diff/
[CurrencyInfo] UNECE Currency Data
http://www.unece.org/etrades/unedocs/repository/codelists/xml/CurrencyCodeList.xml
[DataFormats] CLDR Data Formats
http://unicode.org/cldr/data_formats.html
[Example] A sample in Locale Data Markup Language
http://unicode.org/cldr/dtd/1.1/ldml-example.xml
[ICUCollation] ICU rule syntax
http://www.icu-project.org/userguide/Collate_Customization.html
[ICUTransforms] Transforms
http://www.icu-project.org/userguide/Transformations.html
Transforms Demo
http://demo.icu-project.org/icu-bin/translit/
[ICUUnicodeSet] ICU UnicodeSet
http://www.icu-project.org/userguide/unicodeSet.html
API
http://www.icu-project.org/apiref/icu4j/com/ibm/icu/text/UnicodeSet.html
[ITUE164] International Telecommunication Union: List Of ITU Recommendation E.164 Assigned Country Codes
available at http://www.itu.int/opb/publications.aspx?parent=T-SP&view=T-SP2
[LocaleExplorer] ICU Locale Explorer
http://demo.icu-project.org/icu-bin/locexp
[LocaleProject] Common Locale Data Repository Project
http://unicode.org/cldr/
[NamingGuideline] OpenI18N Locale Naming Guideline
formerly at http://www.openi18n.org/docs/text/LocNameGuide-V10.txt
[RBNF] Rule-Based Number Format
http://www.icu-project.org/apiref/icu4c/classRuleBasedNumberFormat.html#_details
[RBBI] Rule-Based Break Iterator
http://www.icu-project.org/userguide/boundaryAnalysis.html
[RFC5234] RFC5234 Augmented BNF for Syntax Specifications: ABNF
http://www.ietf.org/rfc/rfc5234.txt
[UCAChart] Collation Chart
http://unicode.org/charts/collation/
[UTCInfo] NIST Time and Frequency Division Home Page
http://tf.nist.gov/
U.S. Naval Observatory: What is Universal Time?
http://aa.usno.navy.mil/faq/docs/UT.php
[WindowsCulture] Windows Culture Info (with  mappings from [BCP47]-style codes to LCIDs)
http://msdn2.microsoft.com/en-us/library/system.globalization.cultureinfo(vs.71).aspx

Acknowledgments

Special thanks to the following people for their continuing overall contributions to the CLDR project, and for their specific contributions in the following areas. These descriptions only touch on the many contributions that they have made.

Other contributors to CLDR are listed on the CLDR Project Page.

Modifications

The following summarizes modifications from the previous revision of this document. Some of the modification notes have an associated bug ticket number, which may be used to look up additional information about the modification; for further information, see Filing Bug Reports.

Revision 25

Revision 34 being a proposed update, only changes between revisions 33 and 35 are summarized here.

Revision 33

Revision 32 being a proposed update, only changes between revisions 31 and 33 are summarized here.

Revision 31

Revision 30 being a proposed update, only changes between revisions 29 and 31 are summarized here.

Revision 29

Revision 28 being a proposed update, only changes between revisions 27 and 29 are summarized here.

Revision 27

Revision 26 being a proposed update, only changes between revisions 25 and 27 are summarized here.

Revision 25

Revision 24 being a proposed update, only changes between revisions 23 and 25 are summarized here.

Revision 23

Revision 22 being a proposed update, only changes between revisions 21 and 23 are summarized here.

Revision 21

Revision 20 being a proposed update, only changes between revisions 19 and 21 are summarized here.

Revision 19

Revision 18 being a proposed update, only changes between revisions 17 and 19 are summarized here.

Revision 17

Revision 16

Revision 15

Revision 14 being a proposed update, only changes between revisions 13 and 15 are summarized here.

Revision 13

Revision 12

Revision 11

Revision 10

Revision 9

Revision 8

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Revision 5