Tags for Identifying Languages
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From: The IESG <email@example.com> To: IETF-Announce <firstname.lastname@example.org> Cc: Internet Architecture Board <email@example.com>, RFC Editor <firstname.lastname@example.org>, ltru mailing list <email@example.com>, ltru chair <firstname.lastname@example.org> Subject: Protocol Action: 'Tags for Identifying Languages' to BCP The IESG has approved the following document: - 'Tags for Identifying Languages ' <draft-ietf-ltru-4646bis-23.txt> as a BCP This document is the product of the Language Tag Registry Update Working Group. The IESG contact persons are Alexey Melnikov and Lisa Dusseault. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-ltru-4646bis-23.txt
Technical Summary This document describes the structure, content, construction, and semantics of language tags for use in cases where it is desirable to indicate the language used in an information object. It also describes how to register values for use in language tags and the creation of user-defined extensions for private interchange. This document is an update of RFC4646. The main change is the addition of thousands of three-letter language subtags for languages for which tagging was not possible up to now. Also, the registry format and procedures were adjusted to deal with this change, and to reflect experience from current practice. Working Group Summary The WG process for this document was mostly smooth and revolving around details. There were some highly contentious issues, but for all of them, a solution was found that was acceptable to the involved parties and works for all scenarios identified. Document Quality The IANA Language Subtag Registry, and the language tags that can be formed according to this document and its predecessor, are widely used across the Internet to identify languages, both in implementations (code) and in a wide range of data. Personnel Martin J. Dürst is the document shepherd. Alexey Melnikov is the responsible AD. RFC Editor Note Please move the reference to RFC 2028 to the Informative section. The document has several references to BCP 47. RFC Editor should check if they are appropriate and how to represent them better. There are several cases of mismatched singulars and plurals in the document, so RFC Editor might want to check for these. Please replace the last paragraph of section 6 with 2 paragraphs: OLD: The registries specified in this document are not suitable for frequent or real-time access to, or retrieval, of the full registry ^ contents. Most applications do not need registry data at all. For others, being able to validate or canonicalize language tags as of a particular registry date will be sufficient, as the registry contents change only occasionally. Changes are announced to <email@example.com>. Changes, or the absence thereof, can also easily be detected by looking at the 'File-Date' record at the start of the registry, or by using features of the protocol used for downloading, without having to download the full registry. NEW: The registries specified in this document are not suitable for frequent or real-time access to, or retrieval of, the full registry ^ ^ contents. Most applications do not need registry data at all. For others, being able to validate or canonicalize language tags as of a particular registry date will be sufficient, as the registry contents change only occasionally. Changes are announced to <firstname.lastname@example.org>. This mailing list is ^^^^^^^^^^^^^^^^^^^^ intended for interested organizations and individuals, not for bulk ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ subscription to trigger automatic software updates. The size of the ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ registry makes it unsuitable for automatic software updates. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Implementers considering integrating the Language Subtag Registry in ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ an automatic updating scheme are strongly advised to distribute only ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ suitably encoded differences, and only via their own infrastructure, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not directly from IANA. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Changes, or the absence thereof, can also easily be detected by looking at the 'File-Date' record at the start of the registry, or by using features of the protocol used for downloading, without having to download the full registry. At the time of publication of ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this document IANA is making the Language Tag registry available ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ over HTTP 1.1. The proper way to update a local copy of the Language ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Subtag Registry using HTTP 1.1 is to use a conditional GET [RFC2616]. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Please add RFC 2616 to the list of Informative references. Please change Mark Davis's email address to email@example.com. Please insert a new section 3.9 that reads: 3.9. Applicability of the Subtag Registry The Language Subtag Registry is the source of data elements used to construct language tags, following rules described in this document. Language tags are designed for indicating linguistic attributes of various content, including not only text but also most media formats such as video or audio. They also form the basis for language and locale negotiation in various protocols and APIs. The registry is therefore applicable to many applications that need some form of language identification, with these limitations: - It is not designed to be the sole data source in the creation of a language selection user interface. For example, the registry does not contain translations for subtag descriptions or for tags composed from the subtags. Sources for localized data based on the registry are generally available, notably [CLDR]. Nor does the registry indicate which subtag combinations are particularly useful or relevant. - It does not provide information indicating relationships between different languages, such as might be used in a user interface to select language tags hierarchically, regionally, or on some other organizational model. - It does not supply information about potential overlap between different language tags, as the notion of what constitutes a language is not precise: several different language tags might be reasonable choices for the same given piece of content. - It does not contain information about appropriate fallback choices when performing language negotiation. A good fallback language might be linguistically unrelated to the specified language. The fact that one language is often used as a fallback language for another is usually a result of outside factors, such as geography, history, or culture--factors which might not apply in all cases. For example, most people who use Breton (a Celtic language used in the Northwest of France) would probably prefer to be served French (a Romance language) if Breton isn't available.