RFC4647 日本語訳
4647 Matching of Language Tags. A. Phillips, M. Davis. September 2006. (Format: TXT=45595 bytes) (Obsoletes RFC3066) (Also BCP0047) (Status: BEST CURRENT PRACTICE)
プログラムでの自動翻訳です。
英語原文
Network Working Group A. Phillips, Ed. Request for Comments: 4647 Yahoo! Inc. BCP: 47 M. Davis, Ed. Obsoletes: 3066 Google Category: Best Current Practice September 2006
Network Working Group A. Phillips, Ed. Request for Comments: 4647 Yahoo! Inc. BCP: 47 M. Davis, Ed. Obsoletes: 3066 Google Category: Best Current Practice September 2006
Matching of Language Tags
Matching of Language Tags
Status of This Memo
Status of This Memo
This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited.
This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright Notice
Copyright (C) The Internet Society (2006).
Copyright (C) The Internet Society (2006).
Abstract
Abstract
This document describes a syntax, called a "language-range", for specifying items in a user's list of language preferences. It also describes different mechanisms for comparing and matching these to language tags. Two kinds of matching mechanisms, filtering and lookup, are defined. Filtering produces a (potentially empty) set of language tags, whereas lookup produces a single language tag. Possible applications include language negotiation or content selection. This document, in combination with RFC 4646, replaces RFC 3066, which replaced RFC 1766.
This document describes a syntax, called a "language-range", for specifying items in a user's list of language preferences. It also describes different mechanisms for comparing and matching these to language tags. Two kinds of matching mechanisms, filtering and lookup, are defined. Filtering produces a (potentially empty) set of language tags, whereas lookup produces a single language tag. Possible applications include language negotiation or content selection. This document, in combination with RFC 4646, replaces RFC 3066, which replaced RFC 1766.
Phillips & Davis Best Current Practice [Page 1] RFC 4647 Matching of Language Tags September 2006
Phillips & Davis Best Current Practice [Page 1] RFC 4647 Matching of Language Tags September 2006
Table of Contents
Table of Contents
1. Introduction ....................................................3
2. The Language Range ..............................................3
2.1. Basic Language Range .......................................4
2.2. Extended Language Range ....................................4
2.3. The Language Priority List .................................5
3. Types of Matching ...............................................6
3.1. Choosing a Matching Scheme .................................6
3.2. Implementation Considerations ..............................7
3.3. Filtering ..................................................8
3.3.1. Basic Filtering .....................................9
3.3.2. Extended Filtering .................................10
3.4. Lookup ....................................................12
3.4.1. Default Values .....................................14
4. Other Considerations ...........................................15
4.1. Choosing Language Ranges ..................................15
4.2. Meaning of Language Tags and Ranges .......................16
4.3. Considerations for Private-Use Subtags ....................17
4.4. Length Considerations for Language Ranges .................17
5. Security Considerations ........................................17
6. Character Set Considerations ...................................17
7. References .....................................................18
7.1. Normative References ......................................18
7.2. Informative References ....................................18
Appendix A. Acknowledgements ......................................19
1. Introduction ....................................................3 2. The Language Range ..............................................3 2.1. Basic Language Range .......................................4 2.2. Extended Language Range ....................................4 2.3. The Language Priority List .................................5 3. Types of Matching ...............................................6 3.1. Choosing a Matching Scheme .................................6 3.2. Implementation Considerations ..............................7 3.3. Filtering ..................................................8 3.3.1. Basic Filtering .....................................9 3.3.2. Extended Filtering .................................10 3.4. Lookup ....................................................12 3.4.1. Default Values .....................................14 4. Other Considerations ...........................................15 4.1. Choosing Language Ranges ..................................15 4.2. Meaning of Language Tags and Ranges .......................16 4.3. Considerations for Private-Use Subtags ....................17 4.4. Length Considerations for Language Ranges .................17 5. Security Considerations ........................................17 6. Character Set Considerations ...................................17 7. References .....................................................18 7.1. Normative References ......................................18 7.2. Informative References ....................................18 Appendix A. Acknowledgements ......................................19
Phillips & Davis Best Current Practice [Page 2] RFC 4647 Matching of Language Tags September 2006
Phillips & Davis Best Current Practice [Page 2] RFC 4647 Matching of Language Tags September 2006
1. Introduction
1. Introduction
Human beings on our planet have, past and present, used a number of languages. There are many reasons why one would want to identify the language used when presenting or requesting information.
Human beings on our planet have, past and present, used a number of languages. There are many reasons why one would want to identify the language used when presenting or requesting information.
Applications, protocols, or specifications that use language identifiers, such as the language tags defined in [RFC4646], sometimes need to match language tags to a user's language preferences.
Applications, protocols, or specifications that use language identifiers, such as the language tags defined in [RFC4646], sometimes need to match language tags to a user's language preferences.
This document defines a syntax (called a language range (Section 2)) for specifying items in the user's list of language preferences (called a language priority list (Section 2.3)), as well as several schemes for selecting or filtering sets of language tags by comparing the language tags to the user's preferences. Applications, protocols, or specifications will have varying needs and requirements that affect the choice of a suitable matching scheme.
This document defines a syntax (called a language range (Section 2)) for specifying items in the user's list of language preferences (called a language priority list (Section 2.3)), as well as several schemes for selecting or filtering sets of language tags by comparing the language tags to the user's preferences. Applications, protocols, or specifications will have varying needs and requirements that affect the choice of a suitable matching scheme.
This document describes how to indicate a user's preferences using language ranges, three schemes for matching these ranges to a set of language tags, and the various practical considerations that apply to implementing and using these schemes.
This document describes how to indicate a user's preferences using language ranges, three schemes for matching these ranges to a set of language tags, and the various practical considerations that apply to implementing and using these schemes.
This document, in combination with [RFC4646], replaces [RFC3066], which replaced [RFC1766].
This document, in combination with [RFC4646], replaces [RFC3066], which replaced [RFC1766].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
2. The Language Range
2. The Language Range
Language tags [RFC4646] are used to help identify languages, whether spoken, written, signed, or otherwise signaled, for the purpose of communication. Applications, protocols, or specifications that use language tags are often faced with the problem of identifying sets of content that share certain language attributes. For example, HTTP/1.1 [RFC2616] describes one such mechanism in its discussion of the Accept-Language header (Section 14.4), which is used when selecting content from servers based on the language of that content.
Language tags [RFC4646] are used to help identify languages, whether spoken, written, signed, or otherwise signaled, for the purpose of communication. Applications, protocols, or specifications that use language tags are often faced with the problem of identifying sets of content that share certain language attributes. For example, HTTP/1.1 [RFC2616] describes one such mechanism in its discussion of the Accept-Language header (Section 14.4), which is used when selecting content from servers based on the language of that content.
It is, thus, useful to have a mechanism for identifying sets of language tags that share specific attributes. This allows users to select or filter the language tags based on specific requirements. Such an identifier is called a "language range".
It is, thus, useful to have a mechanism for identifying sets of language tags that share specific attributes. This allows users to select or filter the language tags based on specific requirements. Such an identifier is called a "language range".
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Phillips & Davis Best Current Practice [Page 3] RFC 4647 Matching of Language Tags September 2006
There are different types of language range, whose specific attributes vary according to their application. Language ranges are similar to language tags: they consist of a sequence of subtags separated by hyphens. In a language range, each subtag MUST either be a sequence of ASCII alphanumeric characters or the single character '*' (%x2A, ASTERISK). The character '*' is a "wildcard" that matches any sequence of subtags. The meaning and uses of wildcards vary according to the type of language range.
There are different types of language range, whose specific attributes vary according to their application. Language ranges are similar to language tags: they consist of a sequence of subtags separated by hyphens. In a language range, each subtag MUST either be a sequence of ASCII alphanumeric characters or the single character '*' (%x2A, ASTERISK). The character '*' is a "wildcard" that matches any sequence of subtags. The meaning and uses of wildcards vary according to the type of language range.
Language tags and thus language ranges are to be treated as case- insensitive: there exist conventions for the capitalization of some of the subtags, but these MUST NOT be taken to carry meaning. Matching of language tags to language ranges MUST be done in a case- insensitive manner.
Language tags and thus language ranges are to be treated as case- insensitive: there exist conventions for the capitalization of some of the subtags, but these MUST NOT be taken to carry meaning. Matching of language tags to language ranges MUST be done in a case- insensitive manner.
2.1. Basic Language Range
2.1. Basic Language Range
A "basic language range" has the same syntax as an [RFC3066] language tag or is the single character "*". The basic language range was originally described by HTTP/1.1 [RFC2616] and later [RFC3066]. It is defined by the following ABNF [RFC4234]:
A "basic language range" has the same syntax as an [RFC3066] language tag or is the single character "*". The basic language range was originally described by HTTP/1.1 [RFC2616] and later [RFC3066]. It is defined by the following ABNF [RFC4234]:
language-range = (1*8ALPHA *("-" 1*8alphanum)) / "*"
alphanum = ALPHA / DIGIT
language-range = (1*8ALPHA *("-" 1*8alphanum)) / "*" alphanum = ALPHA / DIGIT
A basic language range differs from the language tags defined in [RFC4646] only in that there is no requirement that it be "well- formed" or be validated against the IANA Language Subtag Registry. Such ill-formed ranges will probably not match anything. Note that the ABNF [RFC4234] in [RFC2616] is incorrect, since it disallows the use of digits anywhere in the 'language-range' (see [RFC2616errata]).
A basic language range differs from the language tags defined in [RFC4646] only in that there is no requirement that it be "well- formed" or be validated against the IANA Language Subtag Registry. Such ill-formed ranges will probably not match anything. Note that the ABNF [RFC4234] in [RFC2616] is incorrect, since it disallows the use of digits anywhere in the 'language-range' (see [RFC2616errata]).
2.2. Extended Language Range
2.2. Extended Language Range
Occasionally, users will wish to select a set of language tags based on the presence of specific subtags. An "extended language range" describes a user's language preference as an ordered sequence of subtags. For example, a user might wish to select all language tags that contain the region subtag 'CH' (Switzerland). Extended language ranges are useful for specifying a particular sequence of subtags that appear in the set of matching tags without having to specify all of the intervening subtags.
Occasionally, users will wish to select a set of language tags based on the presence of specific subtags. An "extended language range" describes a user's language preference as an ordered sequence of subtags. For example, a user might wish to select all language tags that contain the region subtag 'CH' (Switzerland). Extended language ranges are useful for specifying a particular sequence of subtags that appear in the set of matching tags without having to specify all of the intervening subtags.
An extended language range can be represented by the following ABNF:
An extended language range can be represented by the following ABNF:
extended-language-range = (1*8ALPHA / "*")
*("-" (1*8alphanum / "*"))
extended-language-range = (1*8ALPHA / "*") *("-" (1*8alphanum / "*"))
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Phillips & Davis Best Current Practice [Page 4] RFC 4647 Matching of Language Tags September 2006
The wildcard subtag '*' can occur in any position in the extended language range, where it matches any sequence of subtags that might occur in that position in a language tag. However, wildcards outside the first position are ignored by Extended Filtering (see Section 3.2.2). The use or absence of one or more wildcards cannot be taken to imply that a certain number of subtags will appear in the matching set of language tags.
The wildcard subtag '*' can occur in any position in the extended language range, where it matches any sequence of subtags that might occur in that position in a language tag. However, wildcards outside the first position are ignored by Extended Filtering (see Section 3.2.2). The use or absence of one or more wildcards cannot be taken to imply that a certain number of subtags will appear in the matching set of language tags.
2.3. The Language Priority List
2.3. The Language Priority List
A user's language preferences will often need to specify more than one language range, and thus users often need to specify a prioritized list of language ranges in order to best reflect their language preferences. This is especially true for speakers of minority languages. A speaker of Breton in France, for example, can specify "br" followed by "fr", meaning that if Breton is available, it is preferred, but otherwise French is the best alternative. It can get more complex: a different user might want to fall back from Skolt Sami to Northern Sami to Finnish.
A user's language preferences will often need to specify more than one language range, and thus users often need to specify a prioritized list of language ranges in order to best reflect their language preferences. This is especially true for speakers of minority languages. A speaker of Breton in France, for example, can specify "br" followed by "fr", meaning that if Breton is available, it is preferred, but otherwise French is the best alternative. It can get more complex: a different user might want to fall back from Skolt Sami to Northern Sami to Finnish.
A "language priority list" is a prioritized or weighted list of language ranges. One well-known example of such a list is the "Accept-Language" header defined in RFC 2616 [RFC2616] (see Section 14.4) and RFC 3282 [RFC3282].
A "language priority list" is a prioritized or weighted list of language ranges. One well-known example of such a list is the "Accept-Language" header defined in RFC 2616 [RFC2616] (see Section 14.4) and RFC 3282 [RFC3282].
The various matching operations described in this document include considerations for using a language priority list. This document does not define the syntax for a language priority list; defining such a syntax is the responsibility of the protocol, application, or specification that uses it. When given as examples in this document, language priority lists will be shown as a quoted sequence of ranges separated by commas, like this: "en, fr, zh-Hant" (which is read "English before French before Chinese as written in the Traditional script").
The various matching operations described in this document include considerations for using a language priority list. This document does not define the syntax for a language priority list; defining such a syntax is the responsibility of the protocol, application, or specification that uses it. When given as examples in this document, language priority lists will be shown as a quoted sequence of ranges separated by commas, like this: "en, fr, zh-Hant" (which is read "English before French before Chinese as written in the Traditional script").
A simple list of ranges is considered to be in descending order of priority. Other language priority lists provide "quality weights" for the language ranges in order to specify the relative priority of the user's language preferences. An example of this is the use of "q" values in the syntax of the "Accept-Language" header (defined in [RFC2616], Section 14.4, and [RFC3282]).
A simple list of ranges is considered to be in descending order of priority. Other language priority lists provide "quality weights" for the language ranges in order to specify the relative priority of the user's language preferences. An example of this is the use of "q" values in the syntax of the "Accept-Language" header (defined in [RFC2616], Section 14.4, and [RFC3282]).
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Phillips & Davis Best Current Practice [Page 5] RFC 4647 Matching of Language Tags September 2006
3. Types of Matching
3. Types of Matching
Matching language ranges to language tags can be done in many different ways. This section describes three such matching schemes, as well as the considerations for choosing between them. Protocols and specifications requiring conformance to this specification MUST clearly indicate the particular mechanism used in selecting or matching language tags.
Matching language ranges to language tags can be done in many different ways. This section describes three such matching schemes, as well as the considerations for choosing between them. Protocols and specifications requiring conformance to this specification MUST clearly indicate the particular mechanism used in selecting or matching language tags.
There are two types of matching scheme in this document. A matching scheme that produces zero or more matching language tags is called "filtering". A matching scheme that produces exactly one match for a given request is called "lookup".
There are two types of matching scheme in this document. A matching scheme that produces zero or more matching language tags is called "filtering". A matching scheme that produces exactly one match for a given request is called "lookup".
3.1. Choosing a Matching Scheme
3.1. Choosing a Matching Scheme
Applications, protocols, and specifications are faced with the decision of what type of matching to use. Sometimes, different styles of matching are suited to different kinds of processing within a particular application or protocol.
Applications, protocols, and specifications are faced with the decision of what type of matching to use. Sometimes, different styles of matching are suited to different kinds of processing within a particular application or protocol.
This document describes three matching schemes:
This document describes three matching schemes:
1. Basic Filtering (Section 3.3.1) matches a language priority list
consisting of basic language ranges (Section 2.1) to sets of
language tags.
1. Basic Filtering (Section 3.3.1) matches a language priority list consisting of basic language ranges (Section 2.1) to sets of language tags.
2. Extended Filtering (Section 3.3.2) matches a language priority
list consisting of extended language ranges (Section 2.2) to sets
of language tags.
2. Extended Filtering (Section 3.3.2) matches a language priority list consisting of extended language ranges (Section 2.2) to sets of language tags.
3. Lookup (Section 3.4) matches a language priority list consisting
of basic language ranges to sets of language tags to find the one
exact language tag that best matches the range.
3. Lookup (Section 3.4) matches a language priority list consisting of basic language ranges to sets of language tags to find the one exact language tag that best matches the range.
Filtering can be used to produce a set of results (such as a collection of documents) by comparing the user's preferences to a set of language tags. For example, when performing a search, filtering can be used to limit the results to items tagged as being in the French language. Filtering can also be used when deciding whether to perform a language-sensitive process on some content. For example, a process might cause paragraphs whose language tag matched the language range "nl" (Dutch) to be displayed in italics within a document.
Filtering can be used to produce a set of results (such as a collection of documents) by comparing the user's preferences to a set of language tags. For example, when performing a search, filtering can be used to limit the results to items tagged as being in the French language. Filtering can also be used when deciding whether to perform a language-sensitive process on some content. For example, a process might cause paragraphs whose language tag matched the language range "nl" (Dutch) to be displayed in italics within a document.
Lookup produces the single result that best matches the user's preferences from the list of available tags, so it is useful in cases in which a single item is required (and for which only a single item
Lookup produces the single result that best matches the user's preferences from the list of available tags, so it is useful in cases in which a single item is required (and for which only a single item
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Phillips & Davis Best Current Practice [Page 6] RFC 4647 Matching of Language Tags September 2006
can be returned). For example, if a process were to insert a human- readable error message into a protocol header, it might select the text based on the user's language priority list. Since the process can return only one item, it is forced to choose a single item and it has to return some item, even if none of the content's language tags match the language priority list supplied by the user.
can be returned). For example, if a process were to insert a human- readable error message into a protocol header, it might select the text based on the user's language priority list. Since the process can return only one item, it is forced to choose a single item and it has to return some item, even if none of the content's language tags match the language priority list supplied by the user.
3.2. Implementation Considerations
3.2. Implementation Considerations
Language tag matching is a tool, and does not by itself specify a complete procedure for the use of language tags. Such procedures are intimately tied to the application protocol in which they occur. When specifying a protocol operation using matching, the protocol MUST specify:
Language tag matching is a tool, and does not by itself specify a complete procedure for the use of language tags. Such procedures are intimately tied to the application protocol in which they occur. When specifying a protocol operation using matching, the protocol MUST specify:
o Which type(s) of language tag matching it uses
o Which type(s) of language tag matching it uses
o Whether the operation returns a single result (lookup) or a
possibly empty set of results (filtering)
o Whether the operation returns a single result (lookup) or a possibly empty set of results (filtering)
o For lookup, what the default item is (or the sequence of
operations or configuration information used to determine the
default) when no matching tag is found. For instance, a protocol
might define the result as failure of the operation, an empty
value, returning some protocol defined or implementation defined
default, or returning i-default [RFC2277].
o For lookup, what the default item is (or the sequence of operations or configuration information used to determine the default) when no matching tag is found. For instance, a protocol might define the result as failure of the operation, an empty value, returning some protocol defined or implementation defined default, or returning i-default [RFC2277].
Applications, protocols, and specifications are not required to validate or understand any of the semantics of the language tags or ranges or of the subtags in them, nor do they require access to the IANA Language Subtag Registry (see Section 3 in [RFC4646]). This simplifies implementation.
Applications, protocols, and specifications are not required to validate or understand any of the semantics of the language tags or ranges or of the subtags in them, nor do they require access to the IANA Language Subtag Registry (see Section 3 in [RFC4646]). This simplifies implementation.
However, designers of applications, protocols, or specifications are encouraged to use the information from the IANA Language Subtag Registry to support canonicalizing language tags and ranges in order to map grandfathered and obsolete tags or subtags into modern equivalents.
However, designers of applications, protocols, or specifications are encouraged to use the information from the IANA Language Subtag Registry to support canonicalizing language tags and ranges in order to map grandfathered and obsolete tags or subtags into modern equivalents.
Applications, protocols, or specifications that canonicalize ranges MUST either perform matching operations with both the canonical and original (unmodified) form of the range or MUST also canonicalize each tag for the purposes of comparison.
Applications, protocols, or specifications that canonicalize ranges MUST either perform matching operations with both the canonical and original (unmodified) form of the range or MUST also canonicalize each tag for the purposes of comparison.
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Phillips & Davis Best Current Practice [Page 7] RFC 4647 Matching of Language Tags September 2006
Note that canonicalizing language ranges makes certain operations impossible. For example, an implementation that canonicalizes the language range "art-lojban" (artificial language, lojban variant) to use the more modern "jbo" (Lojban) cannot be used to select just the items with the older tag.
Note that canonicalizing language ranges makes certain operations impossible. For example, an implementation that canonicalizes the language range "art-lojban" (artificial language, lojban variant) to use the more modern "jbo" (Lojban) cannot be used to select just the items with the older tag.
Applications, protocols, or specifications that use basic ranges might sometimes receive extended language ranges instead. An application, protocol, or specification MUST choose to a) map extended language ranges to basic ranges using the algorithm below, b) reject any extended language ranges in the language priority list that are not valid basic language ranges, or c) treat each extended language range as if it were a basic language range, which will have the same result as ignoring them, since these ranges will not match any valid language tags.
Applications, protocols, or specifications that use basic ranges might sometimes receive extended language ranges instead. An application, protocol, or specification MUST choose to a) map extended language ranges to basic ranges using the algorithm below, b) reject any extended language ranges in the language priority list that are not valid basic language ranges, or c) treat each extended language range as if it were a basic language range, which will have the same result as ignoring them, since these ranges will not match any valid language tags.
An extended language range is mapped to a basic language range as follows: if the first subtag is a '*' then the entire range is treated as "*", otherwise each wildcard subtag is removed. For example, the extended language range "en-*-US" maps to "en-US" (English, United States).
An extended language range is mapped to a basic language range as follows: if the first subtag is a '*' then the entire range is treated as "*", otherwise each wildcard subtag is removed. For example, the extended language range "en-*-US" maps to "en-US" (English, United States).
Applications, protocols, or specifications, in addressing their particular requirements, can offer pre-processing or configuration options. For example, an implementation could allow a user to associate or map a particular language range to a different value. Such a user might wish to associate the language range subtags 'nn' (Nynorsk Norwegian) and 'nb' (Bokmal Norwegian) with the more general subtag 'no' (Norwegian). Or perhaps a user would want to associate requests for the range "zh-Hans" (Chinese as written in the Simplified script) with content bearing the language tag "zh-CN" (Chinese as used in China, where the Simplified script is predominant). Documentation on how the ranges or tags are altered, prioritized, or compared in the subsequent match in such an implementation will assist users in making these types of configuration choices.
Applications, protocols, or specifications, in addressing their particular requirements, can offer pre-processing or configuration options. For example, an implementation could allow a user to associate or map a particular language range to a different value. Such a user might wish to associate the language range subtags 'nn' (Nynorsk Norwegian) and 'nb' (Bokmal Norwegian) with the more general subtag 'no' (Norwegian). Or perhaps a user would want to associate requests for the range "zh-Hans" (Chinese as written in the Simplified script) with content bearing the language tag "zh-CN" (Chinese as used in China, where the Simplified script is predominant). Documentation on how the ranges or tags are altered, prioritized, or compared in the subsequent match in such an implementation will assist users in making these types of configuration choices.
3.3. Filtering
3.3. Filtering
Filtering is used to select the set of language tags that matches a given language priority list. It is called "filtering" because this set might contain no items at all or it might return an arbitrarily large number of matching items: as many items as match the language priority list, thus "filtering out" the non-matching items.
Filtering is used to select the set of language tags that matches a given language priority list. It is called "filtering" because this set might contain no items at all or it might return an arbitrarily large number of matching items: as many items as match the language priority list, thus "filtering out" the non-matching items.
In filtering, each language range represents the least specific language tag (that is, the language tag with fewest number of subtags) that is an acceptable match. All of the language tags in
In filtering, each language range represents the least specific language tag (that is, the language tag with fewest number of subtags) that is an acceptable match. All of the language tags in
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Phillips & Davis Best Current Practice [Page 8] RFC 4647 Matching of Language Tags September 2006
the matching set of tags will have an equal or greater number of subtags than the language range. Every non-wildcard subtag in the language range will appear in every one of the matching language tags. For example, if the language priority list consists of the range "de-CH" (German as used in Switzerland), one might see tags such as "de-CH-1996" (German as used in Switzerland, orthography of 1996) but one will never see a tag such as "de" (because the 'CH' subtag is missing).
the matching set of tags will have an equal or greater number of subtags than the language range. Every non-wildcard subtag in the language range will appear in every one of the matching language tags. For example, if the language priority list consists of the range "de-CH" (German as used in Switzerland), one might see tags such as "de-CH-1996" (German as used in Switzerland, orthography of 1996) but one will never see a tag such as "de" (because the 'CH' subtag is missing).
If the language priority list (see Section 2.3) contains more than one range, the content returned is typically ordered in descending level of preference, but it MAY be unordered, according to the needs of the application or protocol.
If the language priority list (see Section 2.3) contains more than one range, the content returned is typically ordered in descending level of preference, but it MAY be unordered, according to the needs of the application or protocol.
Some examples of applications where filtering might be appropriate include:
Some examples of applications where filtering might be appropriate include:
o Applying a style to sections of a document in a particular set of
languages.
o Applying a style to sections of a document in a particular set of languages.
o Displaying the set of documents containing a particular set of
keywords written in a specific set of languages.
o Displaying the set of documents containing a particular set of keywords written in a specific set of languages.
o Selecting all email items written in a specific set of languages.
o Selecting all email items written in a specific set of languages.
o Selecting audio files spoken in a particular language.
o Selecting audio files spoken in a particular language.
Filtering seems to imply that there is a semantic relationship between language tags that share the same prefix. While this is often the case, it is not always true: the language tags that match a specific language range do not necessarily represent mutually intelligible languages.
Filtering seems to imply that there is a semantic relationship between language tags that share the same prefix. While this is often the case, it is not always true: the language tags that match a specific language range do not necessarily represent mutually intelligible languages.
3.3.1. Basic Filtering
3.3.1. Basic Filtering
Basic filtering compares basic language ranges to language tags. Each basic language range in the language priority list is considered in turn, according to priority. A language range matches a particular language tag if, in a case-insensitive comparison, it exactly equals the tag, or if it exactly equals a prefix of the tag such that the first character following the prefix is "-". For example, the language-range "de-de" (German as used in Germany) matches the language tag "de-DE-1996" (German as used in Germany, orthography of 1996), but not the language tags "de-Deva" (German as written in the Devanagari script) or "de-Latn-DE" (German, Latin script, as used in Germany).
Basic filtering compares basic language ranges to language tags. Each basic language range in the language priority list is considered in turn, according to priority. A language range matches a particular language tag if, in a case-insensitive comparison, it exactly equals the tag, or if it exactly equals a prefix of the tag such that the first character following the prefix is "-". For example, the language-range "de-de" (German as used in Germany) matches the language tag "de-DE-1996" (German as used in Germany, orthography of 1996), but not the language tags "de-Deva" (German as written in the Devanagari script) or "de-Latn-DE" (German, Latin script, as used in Germany).
Phillips & Davis Best Current Practice [Page 9] RFC 4647 Matching of Language Tags September 2006
Phillips & Davis Best Current Practice [Page 9] RFC 4647 Matching of Language Tags September 2006
The special range "*" in a language priority list matches any tag. A protocol that uses language ranges MAY specify additional rules about the semantics of "*"; for instance, HTTP/1.1 [RFC2616] specifies that the range "*" matches only languages not matched by any other range within an "Accept-Language" header.
The special range "*" in a language priority list matches any tag. A protocol that uses language ranges MAY specify additional rules about the semantics of "*"; for instance, HTTP/1.1 [RFC2616] specifies that the range "*" matches only languages not matched by any other range within an "Accept-Language" header.
Basic filtering is identical to the type of matching described in [RFC3066], Section 2.5 (Language-range).
Basic filtering is identical to the type of matching described in [RFC3066], Section 2.5 (Language-range).
3.3.2. Extended Filtering
3.3.2. Extended Filtering
Extended filtering compares extended language ranges to language tags. Each extended language range in the language priority list is considered in turn, according to priority. A language range matches a particular language tag if each respective list of subtags matches. To determine a match:
Extended filtering compares extended language ranges to language tags. Each extended language range in the language priority list is considered in turn, according to priority. A language range matches a particular language tag if each respective list of subtags matches. To determine a match:
1. Split both the extended language range and the language tag being
compared into a list of subtags by dividing on the hyphen (%x2D)
character. Two subtags match if either they are the same when
compared case-insensitively or the language range's subtag is the
wildcard '*'.
1. Split both the extended language range and the language tag being compared into a list of subtags by dividing on the hyphen (%x2D) character. Two subtags match if either they are the same when compared case-insensitively or the language range's subtag is the wildcard '*'.
2. Begin with the first subtag in each list. If the first subtag in
the range does not match the first subtag in the tag, the overall
match fails. Otherwise, move to the next subtag in both the
range and the tag.
2. Begin with the first subtag in each list. If the first subtag in the range does not match the first subtag in the tag, the overall match fails. Otherwise, move to the next subtag in both the range and the tag.
3. While there are more subtags left in the language range's list:
3. While there are more subtags left in the language range's list:
A. If the subtag currently being examined in the range is the
wildcard ('*'), move to the next subtag in the range and
continue with the loop.
A. If the subtag currently being examined in the range is the wildcard ('*'), move to the next subtag in the range and continue with the loop.
B. Else, if there are no more subtags in the language tag's
list, the match fails.
B. Else, if there are no more subtags in the language tag's list, the match fails.
C. Else, if the current subtag in the range's list matches the
current subtag in the language tag's list, move to the next
subtag in both lists and continue with the loop.
C. Else, if the current subtag in the range's list matches the current subtag in the language tag's list, move to the next subtag in both lists and continue with the loop.
D. Else, if the language tag's subtag is a "singleton" (a single
letter or digit, which includes the private-use subtag 'x')
the match fails.
D. Else, if the language tag's subtag is a "singleton" (a single letter or digit, which includes the private-use subtag 'x') the match fails.
E. Else, move to the next subtag in the language tag's list and
continue with the loop.
E. Else, move to the next subtag in the language tag's list and continue with the loop.
Phillips & Davis Best Current Practice [Page 10] RFC 4647 Matching of Language Tags September 2006
Phillips & Davis Best Current Practice [Page 10] RFC 4647 Matching of Language Tags September 2006
4. When the language range's list has no more subtags, the match
succeeds.
4. When the language range's list has no more subtags, the match succeeds.
Subtags not specified, including those at the end of the language range, are thus treated as if assigned the wildcard value '*'. Much like basic filtering, extended filtering selects content with arbitrarily long tags that share the same initial subtags as the language range. In addition, extended filtering selects language tags that contain any intermediate subtags not specified in the language range. For example, the extended language range "de-*-DE" (or its synonym "de-DE") matches all of the following tags:
Subtags not specified, including those at the end of the language range, are thus treated as if assigned the wildcard value '*'. Much like basic filtering, extended filtering selects content with arbitrarily long tags that share the same initial subtags as the language range. In addition, extended filtering selects language tags that contain any intermediate subtags not specified in the language range. For example, the extended language range "de-*-DE" (or its synonym "de-DE") matches all of the following tags:
de-DE (German, as used in Germany)
de-DE (German, as used in Germany)
de-de (German, as used in Germany)
de-de (German, as used in Germany)
de-Latn-DE (Latin script)
de-Latn-DE (Latin script)
de-Latf-DE (Fraktur variant of Latin script)
de-Latf-DE (Fraktur variant of Latin script)
de-DE-x-goethe (private-use subtag)
de-DE-x-goethe (private-use subtag)
de-Latn-DE-1996 (orthography of 1996)
de-Latn-DE-1996 (orthography of 1996)
de-Deva-DE (Devanagari script)
de-Deva-DE (Devanagari script)
The same range does not match any of the following tags for the reasons shown:
The same range does not match any of the following tags for the reasons shown:
de (missing 'DE')
de (missing 'DE')
de-x-DE (singleton 'x' occurs before 'DE')
de-x-DE (singleton 'x' occurs before 'DE')
de-Deva ('Deva' not equal to 'DE')
de-Deva ('Deva' not equal to 'DE')
Note: [RFC4646] defines each type of subtag (language, script, region, and so forth) according to position, size, and content. This means that subtags in a language range can only match specific types of subtags in a language tag. For example, a subtag such as 'Latn' is always a script subtag (unless it follows a singleton) while a subtag such as 'nedis' can only match the equivalent variant subtag. Two-letter subtags in the initial position have a different type (language) than two-letter subtags in later positions (region). This is the reason why a wildcard in the extended language range is significant in the first position but is ignored in all other positions.
以下に注意してください。 位置、サイズ、および内容に従って、[RFC4646]はsubtag(言語、スクリプト、領域など)の各タイプを定義します。 これは、言語範囲の「副-タグ」が言語タグの「副-タグ」の特定のタイプに合うことができるだけであることを意味します。 例えば、'nedis'などのsubtagは同等な異形subtagに合うことができるだけですが、いつも'Latn'などのsubtagはスクリプトsubtag(単独個体に続かない場合)です。 最初の位置の2文字の「副-タグ」には、後の位置(領域)の2文字の「副-タグ」と異なったタイプ(言語)があります。 これは拡張言語範囲のワイルドカードが第1ポジションで重要ですが、他のすべての位置で無視される理由です。
Phillips & Davis Best Current Practice [Page 11] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[11ページ]RFC4647マッチングは2006年9月にタグ付けをします。
3.4. Lookup
3.4. ルックアップ
Lookup is used to select the single language tag that best matches the language priority list for a given request. When performing lookup, each language range in the language priority list is considered in turn, according to priority. By contrast with filtering, each language range represents the most specific tag that is an acceptable match. The first matching tag found, according to the user's priority, is considered the closest match and is the item returned. For example, if the language range is "de-ch", a lookup operation can produce content with the tags "de" or "de-CH" but never content with the tag "de-CH-1996". If no language tag matches the request, the "default" value is returned.
ルックアップは、与えられた要求のための言語優先権リストに最もよく合っている単一の言語タグを選択するのに使用されます。 ルックアップを実行するとき、言語優先権リストのそれぞれの言語範囲は順番に、順位によって考えられます。 対照的に、フィルタリングで、それぞれの言語範囲は許容できるマッチである最も特定のタグを表します。 ユーザの優先権に従って見つけられた最初の合っているタグは、最も近いマッチであると考えられて、返された商品です。 例えば、言語範囲が「反-ch」であるなら、ルックアップ操作はタグ「反-CH-1996」でどんな"de"というタグがある内容も「反-CH」にもかかわらず、決して内容も作り出すことができません。 どんな言語タグも要求に合っていないなら、「デフォルト」値を返します。
For example, if an application inserts some dynamic content into a document, returning an empty string if there is no exact match is not an option. Instead, the application "falls back" until it finds a matching language tag associated with a suitable piece of content to insert. Some applications of lookup include:
例えば、アプリケーションが何らかのダイナミックな内容をドキュメントに挿入するなら、完全な一致が全くなければ空のストリングを返すのは、オプションではありません。 代わりに、合っている言語タグが挿入する適当な内容に関連しているのがわかるまで、アプリケーションは「後ろへ下がります」。 ルックアップのいくつかのアプリケーションは:
o Selection of a template containing the text for an automated email
response.
o 自動化されたメール応答のためのテキストを含むテンプレートの選択。
o Selection of an item containing some text for inclusion in a
particular Web page.
o 特定のウェブページでの包含のための何らかのテキストを含む項目の選択。
o Selection of a string of text for inclusion in an error log.
o 障害記録での包含のためのテキストのストリングの選択。
o Selection of an audio file to play as a prompt in a phone system.
o 電話システムにおけるプロンプトとして使うオーディオファイルの選択。
In the lookup scheme, the language range is progressively truncated from the end until a matching language tag is located. Single letter or digit subtags (including both the letter 'x', which introduces private-use sequences, and the subtags that introduce extensions) are removed at the same time as their closest trailing subtag. For example, starting with the range "zh-Hant-CN-x-private1-private2" (Chinese, Traditional script, China, two private-use tags) the lookup progressively searches for content as shown below:
ルックアップ体系では、合っている言語タグが見つけられるまで、言語範囲は次第に終わりの先端を切られます。 ただ一つの手紙かケタ「副-タグ」(私用系列を紹介する文字'x'と拡大を導入する「副-タグ」の両方を含んでいる)がそれらの最も近い引きずっているsubtagと同時に取り外されます。 例えば、範囲から始まる、「zh-Hant-CN-x-private1-private2"、(中国的、そして、伝統的な文字、中国、2個の私用タグ) ルックアップは次第に以下に示すように内容を検索します:、」
Example of a Lookup Fallback Pattern
ルックアップ後退パターンに関する例
Range to match: zh-Hant-CN-x-private1-private2 1. zh-Hant-CN-x-private1-private2 2. zh-Hant-CN-x-private1 3. zh-Hant-CN 4. zh-Hant 5. zh 6. (default)
合うには、及んでください: zh-Hant-CN-x-private1-private2 1. zh-Hant-CN-x-private1-private2 2. zh-Hant-CN-x-private1 3. zh-Hant-CN4zh-Hant5zh6。 (デフォルト)
Phillips & Davis Best Current Practice [Page 12] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[12ページ]RFC4647マッチングは2006年9月にタグ付けをします。
This fallback behavior allows some flexibility in finding a match. Without fallback, the default content would be returned immediately if exactly matching content is unavailable. With fallback, a result more closely matching the user request can be provided.
この後退の振舞いはマッチを見つける際に何らかの柔軟性を許容します。 後退がなければ、まさに合っている内容が入手できないなら、すぐに、デフォルト内容を返すでしょう。 後退に、より密接にユーザ要求に合っている結果は提供できます。
Extensions and unrecognized private-use subtags might be unrelated to a particular application of lookup. Since these subtags come at the end of the subtag sequence, they are removed first during the fallback process and usually pose no barrier to interoperability. However, an implementation MAY remove these from ranges prior to performing the lookup (provided the implementation also removes them from the tags being compared). Such modification is internal to the implementation and applications, protocols, or specifications SHOULD NOT remove or modify subtags in content that they return or forward, because this removes information that can be used elsewhere.
拡大と認識されていない私用「副-タグ」はルックアップの特定用途に関係ないかもしれません。 これらの「副-タグ」がsubtag系列の終わりで来るので、彼らは、最初に、後退プロセスの間、移されて、通常、バリアに全く相互運用性にポーズをとらせません。 しかしながら、ルックアップを実行する前に、実装は範囲からこれらを取り除くかもしれません(また、実装が比較されるタグからそれらを取り除くなら)。 そのような変更が実装に内部であり、アプリケーション、プロトコル、または仕様SHOULD NOTがそれらが返す内容か前方に「副-タグ」を取り外すか、または変更します、これがほかの場所で使用できる情報を取り除くので。
The special language range "*" matches any language tag. In the lookup scheme, this range does not convey enough information by itself to determine which language tag is most appropriate, since it matches everything. If the language range "*" is followed by other language ranges, it is skipped. If the language range "*" is the only one in the language priority list or if no other language range follows, the default value is computed and returned.
特別な言語範囲「*」はどんな言語タグにも合っています。 ルックアップ体系では、この範囲はそれ自体でどの言語タグが最も適切であるかを決定できるくらいの情報を伝えません、すべてを合わせるので。 他の言語範囲が言語範囲「*」のあとに続いているなら、それはスキップされます。 言語範囲「*」が言語優先権リストの唯一無二であるか他の言語範囲が全く続かないなら、デフォルト値は、計算されて、返されます。
In some cases, the language priority list can contain one or more extended language ranges (as, for example, when the same language priority list is used as input for both lookup and filtering operations). Wildcard values in an extended language range normally match any value that can occur in that position in a language tag. Since only one item can be returned for any given lookup request, wildcards in a language range have to be processed in a consistent manner or the same request will produce widely varying results. Applications, protocols, or specifications that accept extended language ranges MUST define which item is returned when more than one item matches the extended language range.
いくつかの場合、言語優先権リストが1つを含むことができますか、または、より拡張している言語は及びます(例えば、同じ言語優先権リストがいつとして使用されているかがルックアップとフィルタリングの両方のために操作を入力したので)。 通常、拡張言語範囲のワイルドカード値は言語タグでその位置に起こることができるどんな値にも合っています。 どんな与えられたルックアップ要求のためにも1個の商品しか返すことができないので、言語範囲のワイルドカードが一貫した方法で処理されなければならない、さもなければ、同じ要求は広く結果を変えながら、作り出されるでしょう。 拡張言語範囲を受け入れるアプリケーション、プロトコル、または仕様が、1つ以上の項目が拡張言語範囲に合っているとどの商品が返されるかを定義しなければなりません。
For example, an implementation could map the extended language ranges
to basic ranges. Another possibility would be for an implementation
to return the matching tag that is first in ASCII-order. If the
language range were "*-CH" ('CH' represents Switzerland) and the set
of tags included "de-CH" (German as used in Switzerland), "fr-CH"
(French, Switzerland), and "it-CH" (Italian, Switzerland), then the
tag "de-CH" would be returned.
例えば、実装は拡張言語範囲を基本的な範囲に写像するかもしれません。 別の可能性は実装が最初にASCII-オーダーにある合っているタグを返すだろうことです。 タグのセットは「反-CH」(スイスで使用されるドイツ語)、「フラン-CH」(フランス語、スイス)、および「かゆみ」(イタリア語、スイス)を含んでいました、そして、「」 言語範囲が*-CHであるなら」('CH'はスイスを代表します)次に、タグ「反-CH」を返すでしょう。
Phillips & Davis Best Current Practice [Page 13] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[13ページ]RFC4647マッチングは2006年9月にタグ付けをします。
3.4.1. Default Values
3.4.1. デフォルト値
Each application, protocol, or specification that uses lookup MUST define the defaulting behavior when no tag matches the language priority list. What this action consists of strongly depends on how lookup is being applied. Some examples of defaulting behavior include:
どんなタグも言語優先権リストに合っていないと、ルックアップを使用する各アプリケーション、プロトコル、または仕様がデフォルトの振舞いを定義しなければなりません。 この動作が何で成るかは強くルックアップがどう適用されているかによります。 デフォルトの振舞いに関するいくつかの例は:
o return an item with no language tag or an item of a non-linguistic
nature, such as an image or sound
o イメージか音などの非言語学の本質の言語タグも項目なしで商品を返してください。
o return a null string as the language tag value, in cases where the
protocol permits the empty value (see, for example, "xml:lang" in
[XML10])
o プロトコルが空の値を可能にする場合における言語タグ価値としてヌルストリングを返してください。([XML10]で例えば、「xml: lang」と見ます)
o return a particular language tag designated for the operation
o 操作のために指定された特定の言語タグを返してください。
o return the language tag "i-default" (see [RFC2277])
o 言語タグ「i-デフォルト」を返してください。([RFC2277]を見ます)
o return an error condition or error message
o エラー条件かエラーメッセージを返してください。
o return a list of available languages for the user to select from
o ユーザが選び抜く利用可能な言語のリストを返してください。
When performing lookup using a language priority list, the progressive search MUST process each language range in the list before seeking or calculating the default.
言語優先権リストを使用することでルックアップを実行するとき、デフォルトについて求めるか、または計算する前に、進歩的な検索はリストのそれぞれの言語範囲を処理しなければなりません。
The default value MAY be calculated or include additional searching or matching. Applications, protocols, or specifications can specify different ways in which users can specify or override the defaults.
デフォルト値は、計算されるか、または追加探すかマッチングを含むかもしれません。 アプリケーション、プロトコル、または仕様がユーザがデフォルトを指定するか、またはくつがえすことができる異なった方法を指定できます。
One common way to provide for a default is to allow a specific language range to be set as the default for a specific type of request. If this approach is chosen, this language range MUST be treated as if it were appended to the end of the language priority list as a whole, rather than after each item in the language priority list. The application, protocol, or specification MUST also define the defaulting behavior if that search fails to find a matching tag or item.
デフォルトに備える1つの一般的な方法は特定の言語範囲が特定のタイプの要求のためのデフォルトとして設定されるのを許容することです。 このアプローチが選ばれているなら、まるで言語優先権リストの各個条の後にというよりむしろ全体で言語優先権リストの終わりまでそれを追加するかのようにこの言語範囲を扱わなければなりません。 また、その検索が合っているタグか項目を見つけないなら、アプリケーション、プロトコル、または仕様がデフォルトの振舞いを定義しなければなりません。
For example, if a particular user's language priority list is "fr-FR, zh-Hant" (French as used in France followed by Chinese as written in the Traditional script) and the program doing the matching had a default language range of "ja-JP" (Japanese as used in Japan), then the program searches as follows:
例えば、特定のユーザの言語優先権リストが「fr-FR、zh-Hant」(書かれるとしてのTraditionalスクリプトによる中国人によって続かれたフランスで使用されるフランス語)であり、マッチングをするプログラムが「ja-JP」(日本で使用される日本語)のデフォルト言語範囲を持っていたなら、プログラムは以下の通り探されます:
Phillips & Davis Best Current Practice [Page 14] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[14ページ]RFC4647マッチングは2006年9月にタグ付けをします。
1. fr-FR 2. fr 3. zh-Hant // next language 4. zh 5. ja-JP // now searching for the default content 6. ja 7. (implementation defined default)
現在デフォルト内容6ja7を捜し求める1. fr-FR2fr3zh-Hant//次の言語4zh5ja-JP//。 (実装の定義されたデフォルト)
4. Other Considerations
4. 他の問題
When working with language ranges and matching schemes, there are some additional points that can influence the choice of either.
言語範囲で働いて、体系を合わせるとき、どちらかの選択に影響を及ぼすことができる追加数ポイントがあります。
4.1. Choosing Language Ranges
4.1. 言語を選ぶのは及びます。
Users indicate their language preferences via the choice of a language range or the list of language ranges in a language priority list. The type of matching affects what the best choice is for a user.
ユーザが言語範囲の選択で彼らの言語好みを示すか、または言語のリストは言語優先権リストのねらいを定めます。 マッチングのタイプは、最も良い選択がユーザのための何であるかに影響します。
Most matching schemes make no attempt to process the semantic meaning of the subtags. The language range is compared, in a case- insensitive manner, to each language tag being matched, using basic string processing. Users SHOULD select language ranges that are well-formed, valid language tags according to [RFC4646] (substituting wildcards as appropriate in extended language ranges).
ほとんどの合っている体系は「副-タグ」の意味意味を処理する試みを全くしません。 言語範囲はケースの神経の鈍い方法で基本的なストリング処理を使用して、合わせられているそれぞれの言語タグと比較されます。 ユーザSHOULDは整形式であることの言語範囲を選択します、[RFC4646]に従った有効な言語タグ(拡張言語でワイルドカードを適宜代入するのは及びます)。
Applications are encouraged to canonicalize language tags and ranges by using the Preferred-Value from the IANA Language Subtag Registry for tags or subtags that have been deprecated. If the user is working with content that might use the older form, the user might want to include both the new and old forms in a language priority list. For example, the tag "art-lojban" is deprecated. The subtag 'jbo' is supposed to be used instead, so the user might use it to form the language range. Or the user might include both in a language priority list: "jbo, art-lojban".
アプリケーションが推奨しないタグか「副-タグ」にIANA Language Subtag RegistryからPreferred-値を使用することによって言語タグと範囲をcanonicalizeするよう奨励されます。 ユーザが、より古いフォームを使用するかもしれない内容で働いているなら、ユーザは言語優先権リストに両方の新しくて古いフォームを含みたがっているかもしれません。 例えば、タグ「芸術-lojban」は推奨しないです。 代わりにsubtag'jbo'によって使用されるべきであるので、ユーザは言語範囲を形成するのにそれを使用するかもしれません。 または、ユーザは言語優先権リストで両方を入れるかもしれません: 「jbo、芸術-lojban。」
Users SHOULD avoid subtags that add no distinguishing value to a language range. When filtering, the fewer the number of subtags that appear in the language range, the more content the range will probably match, while in lookup unnecessary subtags can cause "better", more-specific content to be skipped in favor of less specific content. For example, the range "de-Latn-DE" returns content tagged "de" instead of content tagged "de-DE", even though the latter is probably a better match.
ユーザSHOULDは言語範囲に区別しない値を加える「副-タグ」を避けます。 範囲がたぶん合う内容は、より多いです、それほど特定でない内容を支持してルックアップでは、不要な「副-タグ」が「より良く」て、より特定の内容をスキップさせることができますがフィルターにかけるとき、言語範囲に現れる「副-タグ」の数が少なければ少ないほど。 例えば、範囲「反-Latn DE」は内容の代わりに満足しているタグ付けをされた"de"にタグ付けをされた「反-DE」を返します、後者はたぶんより良いマッチですが。
Phillips & Davis Best Current Practice [Page 15] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[15ページ]RFC4647マッチングは2006年9月にタグ付けをします。
Whether a subtag adds distinguishing value can depend on the context of the request. For example, a user who reads both Simplified and Traditional Chinese, but who prefers Simplified, might use the range "zh" for filtering (matching all items that user can read) but "zh-Hans" for lookup (making sure that user gets the preferred form if it's available, but the fallback to "zh" will still work). On the other hand, content in this case ought to be labeled as "zh-Hans" (or "zh-Hant" if that applies) for filtering, while for lookup, if there is either "zh-Hans" content or "zh-Hant" content, one of them (the one considered 'default') also ought to be made available with the simple "zh". Note that the user can create a language priority list "zh-Hans, zh" that delivers the best possible results for both schemes. If the user cannot be sure which scheme is being used (or if more than one might be applied to a given request), the user SHOULD specify the most specific (largest number of subtags) range first and then supply shorter prefixes later in the list to ensure that filtering returns a complete set of tags.
subtagが値を区別しながら加えるかどうかが要求の文脈に依存できます。 例えば、SimplifiedとTraditionalの両方に中国語を読み込みますが、Simplifiedを好むユーザは、ルックアップのために「zh-ハンス」だけ、をフィルターにかけること(ユーザが読むことができるすべての項目を合わせる)に範囲"zh"を使用するかもしれません(確実にそのユーザを作ると、それが利用可能であるなら、好まれた形は得られますが、それでも、"zh"への後退は働くでしょう)。 他方では、この場合、内容はフィルタリングのために「zh-ハンス」としてラベルされるべきです("zh-Hant"はそれであるなら適用します)、また、ルックアップにおいて、「zh-ハンス」内容か"zh-Hant"内容のどちらかがあれば、それら('デフォルト'であると考えられたもの)の1つを簡単な"zh"で利用可能にするべきですが。 ユーザが「zh-ハンス、zh」という両方の体系のために可能な限り良い結果を提供する言語優先権リストを作成できることに注意してください。 ユーザがどの体系が使用されているかを確信しているはずがないなら(1つ以上が与えられた要求に適用されるかもしれないなら)、ユーザSHOULDは、最初に、最も特定(「副-タグ」の最多数)の範囲を指定して、後でフィルタリングが完全なセットのタグを返すのを保証するためにリストで、より短い接頭語を供給します。
Many languages are written predominantly in a single script. This is usually recorded in the Suppress-Script field in that language subtag's registry entry. For these languages, script subtags SHOULD NOT be used to form a language range. Thus, the language range "en-Latn" is inappropriate in most cases (because the vast majority of English documents are written in the Latin script and thus the 'en' language subtag has a Suppress-Script field for 'Latn' in the registry).
多くの言語がただ一つのスクリプトで支配的に書かれています。 通常、これはその言語subtagの登録エントリーにおけるSuppress-スクリプト分野に記録されます。 これらの言語のために、subtags SHOULDに原稿を書いてください。言語範囲を形成するのは使用されません。 したがって、多くの場合、言語範囲「アン-Latn」は不適当です(かなりの大多数のイギリスのドキュメントがラテン語のスクリプトで書かれていて、その結果、'アン'言語subtagが登録に'Latn'のためのSuppress-スクリプト分野を持っているので)。
When working with tags and ranges, note that extensions and most private-use subtags are orthogonal to language tag matching, in that they specify additional attributes of the text not related to the goals of most matching schemes. Users SHOULD avoid using these subtags in language ranges, since they interfere with the selection of available content. When used in language tags (as opposed to ranges), these subtags normally do not interfere with filtering (Section 3), since they appear at the end of the tag and will match all prefixes. Lookup (Section 3.4) implementations are advised to ignore unrecognized private-use and extension subtags when performing language tag fallback.
タグと範囲で働いているときには拡大とほとんどの私用「副-タグ」が言語タグマッチングと直交していることに注意してください、体系を最も合わせるという目標に関連しないテキストの追加属性を指定するので。 ユーザSHOULDは、利用可能な内容の選択を妨げるので言語範囲でこれらの「副-タグ」を使用するのを避けます。 言語タグ(範囲と対照的に)で使用される場合、通常、これらの「副-タグ」は(セクション3)をフィルターにかけるのを妨げません、彼らがタグの端に現れて、すべての接頭語に合うので。 言語タグ後退を実行するとき、ルックアップ(セクション3.4)実装が認識されていない私用と拡大「副-タグ」を無視するように教えられます。
4.2. Meaning of Language Tags and Ranges
4.2. 言語タグと範囲の意味
Selecting language tags using language ranges requires some understanding by users of what they are selecting. The meanings of the various subtags in a language range are identical to their meanings in a language tag (see Section 4.2 in [RFC4646]), with the addition that the wildcard "*" represents any matching sequence of values.
言語範囲を使用することで言語タグを選択するのは彼らが選択していることに関するユーザによる何らかの理解を必要とします。 言語範囲の様々な「副-タグ」の意味は値の系列を合わせるワイルドカード「*」が表す追加で言語タグでの彼らの意味と同じ([RFC4646]でセクション4.2を見る)いずれでもあります。
Phillips & Davis Best Current Practice [Page 16] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[16ページ]RFC4647マッチングは2006年9月にタグ付けをします。
4.3. Considerations for Private-Use Subtags
4.3. 私用Subtagsのための問題
Private agreement is necessary between the parties that intend to use or exchange language tags that contain private-use subtags. Great caution SHOULD be used in employing private-use subtags in content or protocols intended for general use. Private-use subtags are simply useless for information exchange without prior arrangement.
個人的な協定が私用「副-タグ」を含む言語タグを使用するつもりであるか、または交換するつもりであるパーティーの間で必要です。 大王は、SHOULDが一般的使用のために意図する内容かプロトコルで私用「副-タグ」を使う際に使用されると警告します。 情報交換には、私用「副-タグ」は先のアレンジメントなしで単に役に立ちません。
The value and semantic meaning of private-use tags and of the subtags used within such a language tag are not defined. Matching private- use tags using language ranges or extended language ranges can result in unpredictable content being returned.
そのような言語タグの中に使用された私用タグと「副-タグ」の値と意味意味は定義されません。 言語範囲か拡張言語範囲を使用する個人的な使用がタグ付けをするマッチングは返される予測できない内容をもたらすことができます。
4.4. Length Considerations for Language Ranges
4.4. 言語範囲への長さの問題
Language ranges are very similar to language tags in terms of content and usage. The same types of restrictions on length that can be applied to language tags can also be applied to language ranges. See [RFC4646] Section 4.3 (Length Considerations).
言語範囲は内容と用法において言語タグと非常に同様です。 また、言語タグに適用できる長さにおける同じタイプの制限を言語範囲に適用できます。 [RFC4646]セクション4.3(長さの問題)を見てください。
5. Security Considerations
5. セキュリティ問題
Language ranges used in content negotiation might be used to infer the nationality of the sender, and thus identify potential targets for surveillance. In addition, unique or highly unusual language ranges or combinations of language ranges might be used to track a specific individual's activities.
満足している交渉に使用される言語範囲は、送付者の国籍を推論して、その結果、監視のために仮想ターゲットを特定するのに使用されるかもしれません。 さらに、ユニークであるか非常に珍しい言語が及ぶか、または言語範囲の組み合わせは、特定の個人の活動を追跡するのに使用されるかもしれません。
This is a special case of the general problem that anything you send is visible to the receiving party. It is useful to be aware that such concerns can exist in some cases.
これは受領者にとって、あなたが送るものは何でも目に見えるという一般的問題の特別なそうです。 いくつかの場合、そのような関心が存在できるのを意識しているのは役に立ちます。
The evaluation of the exact magnitude of the threat, and any possible countermeasures, is left to each application or protocol.
脅威の正確な大きさの評価、およびどんな可能な対策も各アプリケーションかプロトコルに残されます。
6. Character Set Considerations
6. 文字コード問題
Language tags permit only the characters A-Z, a-z, 0-9, and HYPHEN- MINUS (%x2D). Language ranges also use the character ASTERISK (%x2A). These characters are present in most character sets, so presentation or exchange of language tags or ranges should not be constrained by character set issues.
言語タグはキャラクタだけのA-Zの、そして、1zの0-9、およびHYPHEN- MINUS(%x2D)を可能にします。 また、言語範囲はキャラクタASTERISK(%x2A)を使用します。 これらのキャラクタがほとんどの文字集合で出席しているので、文字集合問題は言語タグか範囲のプレゼンテーションか交換を抑制するべきではありません。
Phillips & Davis Best Current Practice [Page 17] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[17ページ]RFC4647マッチングは2006年9月にタグ付けをします。
7. References
7. 参照
7.1. Normative References
7.1. 引用規格
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119] ブラドナー、S.、「Indicate Requirement LevelsへのRFCsにおける使用のためのキーワード」、BCP14、RFC2119、1997年3月。
[RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
Languages", BCP 18, RFC 2277, January 1998.
[RFC2277] Alvestrand、H.、「文字コードと言語に関するIETF方針」、BCP18、RFC2277、1998年1月。
[RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", RFC 4234, October 2005.
エド[RFC4234]クロッカー、D.、P.Overell、「構文仕様のための増大しているBNF:」 "ABNF"、2005年10月のRFC4234。
[RFC4646] Phillips, A., Ed., and M. Davis, Ed., "Tags for
Identifying Languages", BCP 47, RFC 4646, September
2006.
[RFC4646]フィリップス、A.、エド、M.デイヴィス、エド、「言語を特定するためのタグ」、BCP47、RFC4646、9月2006日
7.2. Informative References
7.2. 有益な参照
[RFC1766] Alvestrand, H., "Tags for the Identification of
Languages", RFC 1766, March 1995.
[RFC1766]Alvestrand、H.、「言語の識別のためのタグ」、RFC1766、1995年3月。
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee,
"Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616,
June 1999.
[RFC2616] フィールディング、R.、Gettys、J.、ムガール人、J.、Frystyk、H.、Masinter、L.、リーチ、P.、およびT.バーナーズ・リー、「HTTP/1.1インチ、RFC2616、1999年ハイパーテキスト転送プロトコル--6月。」
[RFC2616errata] IETF, "HTTP/1.1 Specification Errata", October 2004,
<http://purl.org/NET/http-errata>.
[RFC2616errata]IETF、「HTTP/1.1仕様誤字」、2004年10月、<http http://purl.org/ネット/誤字>。
[RFC3066] Alvestrand, H., "Tags for the Identification of
Languages", BCP 47, RFC 3066, January 2001.
[RFC3066] Alvestrand、H.、「言語の識別のためのタグ」、BCP47、RFC3066、2001年1月。
[RFC3282] Alvestrand, H., "Content Language Headers", RFC 3282,
May 2002.
[RFC3282]Alvestrand(H.、「満足している言語ヘッダー」、RFC3282)は2002がそうするかもしれません。
[XML10] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E.,
and F. Yergeau, "Extensible Markup Language (XML) 1.0
(Third Edition)", World Wide Web Consortium
Recommendation, February 2004,
<http://www.w3.org/TR/REC-xml>.
T.、パオリ、J.、Sperberg-マックィーン、C.、Maler、E.、およびF.Yergeau、「拡張マークアップ言語(XML)1.0(第3版)」を[XML10]は、いななかせます、ワールドワイドウェブコンソーシアム推薦、2004年2月、<http://www.w3.org/TR/REC-xml>。
Phillips & Davis Best Current Practice [Page 18] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[18ページ]RFC4647マッチングは2006年9月にタグ付けをします。
Appendix A. Acknowledgements
付録A.承認
Any list of contributors is bound to be incomplete; please regard the following as only a selection from the group of people who have contributed to make this document what it is today.
貢献者のどんなリストも不完全であることが制限されています。 このドキュメントを今日現在の姿にするように貢献した人々のグループから以下を選択だけと見なしてください。
The contributors to [RFC1766] and [RFC3066], each of which was a precursor to this document, contributed greatly to the development of language tag matching, and, in particular, the basic language range and the basic matching scheme. This document was originally part of [RFC4646], but was split off before that document's completion. Thus, directly or indirectly, those acknowledged in [RFC4646] also had a hand in the development of this document, and work done prior to the split is acknowledged in that document.
[RFC1766]と[RFC3066]の貢献者は特にタグマッチング、基本的な言語範囲、および基本的な合っている体系を言語の発達に大いに寄付しました。それはそれぞれこのドキュメントへの先駆でした。 このドキュメントは、元々の[RFC4646]の一部でしたが、そのドキュメントの完成の前に裂かれました。 また、このようにして、直接または間接的に、[RFC4646]で承認されたものはこのドキュメントの開発に関与しました、そして、分裂の前に行われた仕事はそのドキュメントで承諾されます。
The following people (in alphabetical order by family name) contributed to this document:
以下の人々(アルファベット順に姓による)はこのドキュメントに貢献しました:
Harald Alvestrand, Stephane Bortzmeyer, Jeremy Carroll, Peter Constable, John Cowan, Mark Crispin, Martin Duerst, Frank Ellermann, Doug Ewell, Debbie Garside, Marion Gunn, Jon Hanna, Kent Karlsson, Erkki Kolehmainen, Jukka Korpela, Ira McDonald, M. Patton, Randy Presuhn, Eric van der Poel, Markus Scherer, Misha Wolf, and many, many others.
ハラルドAlvestrand、ステファーヌBortzmeyer、ジェレミー・キャロル、ピーター・コンスタブル、ジョン・カウァン、マーク・クリスピン、マーチンDuerst、フランクEllermann、ダグ・イーウェル、デビーGarside、マリオン・ガン、ジョン・ハンナ、ケントカールソン、エルッキ・コレマイネン、ユッカKorpela、イラ・マクドナルド、M.パットン、ランディPresuhn、エリック・バンderポール、マーカス・シェーラー、ミーシャ・ヴォルフ、および多くの他のもの。
Very special thanks must go to Harald Tveit Alvestrand, who originated RFCs 1766 and 3066, and without whom this document would not have been possible.
非常に特別な感謝はハラルドTveit Alvestrandに行かなければなりません。(Tveit AlvestrandなしでRFCs1766と3066を溯源して、このドキュメントは可能でなかったでしょう)。
Authors' Addresses
作者のアドレス
Addison Phillips (Editor) Yahoo! Inc.
アディソンフィリップス(エディタ)Yahoo!株式会社
EMail: addison@inter-locale.com
メール: addison@inter-locale.com
Mark Davis (Editor) Google
マーク・デイビス(エディタ)Google
EMail: mark.davis@macchiato.com or mark.davis@google.com
メール: mark.davis@macchiato.com かmark.davis@google.com
Phillips & Davis Best Current Practice [Page 19] RFC 4647 Matching of Language Tags September 2006
言語のフィリップスとデイヴィス最も良い現在の習慣[19ページ]RFC4647マッチングは2006年9月にタグ付けをします。
Full Copyright Statement
完全な著作権宣言文
Copyright (C) The Internet Society (2006).
Copyright(C)インターネット協会(2006)。
This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights.
このドキュメントはBCP78に含まれた権利、ライセンス、および制限を受けることがあります、そして、そこに詳しく説明されるのを除いて、作者は彼らのすべての権利を保有します。
This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
このドキュメントと「そのままで」という基礎と貢献者、その人が代表する組織で提供するか、または後援されて、インターネット協会とインターネット・エンジニアリング・タスク・フォースはすべての保証を放棄します、と急行ORが含意したということであり、他を含んでいて、ここに含まれて、情報の使用がここに侵害しないどんな保証も少しもまっすぐになるという情報か市場性か特定目的への適合性のどんな黙示的な保証。
Intellectual Property
知的所有権
The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79.
IETFはどんなIntellectual Property Rightsの正当性か範囲、実装に関係すると主張されるかもしれない他の権利、本書では説明された技術の使用またはそのような権利の下におけるどんなライセンスも利用可能であるかもしれない、または利用可能でないかもしれない範囲に関しても立場を全く取りません。 または、それはそれを表しません。どんなそのような権利も特定するどんな独立している取り組みも作りました。 BCP78とBCP79でRFCドキュメントの権利に関する手順に関する情報を見つけることができます。
Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr.
IPR公開のコピーが利用可能に作られるべきライセンスの保証、または一般的な免許を取得するのが作られた試みの結果をIETF事務局といずれにもしたか、または http://www.ietf.org/ipr のIETFのオンラインIPR倉庫からこの仕様のimplementersかユーザによるそのような所有権の使用のために許可を得ることができます。
The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org.
IETFはこの規格を実装するのに必要であるかもしれない技術をカバーするかもしれないどんな著作権もその注目していただくどんな利害関係者、特許、特許出願、または他の所有権も招待します。 ietf-ipr@ietf.org のIETFに情報を扱ってください。
Acknowledgement
承認
Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA).
RFC Editor機能のための基金はIETF Administrative Support Activity(IASA)によって提供されます。
Phillips & Davis Best Current Practice [Page 20]
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