RFC-5646
RFC-5646 is a specification published by the Internet Engineering Task Force (IETF) which defines the Tags for Identifying Languages. It updates and obsoletes RFC-4646 and RFC-4647, introducing enhancements to the language tag system used for identifying languages in various internet protocols and applications.
Background
The need for a standardized way to identify languages arose with the growth of the internet, where content in multiple languages needed to be accurately tagged for processing, rendering, and user interaction. Earlier standards like RFC-1766 and its updates were found insufficient to handle the increasing complexity and diversity of languages and dialects.
Key Features
- Extended Language Subtags: RFC-5646 allows for more detailed language identification through the use of extended subtags, which can specify regional variants, scripts, and even specific dialects.
- Grandfathered Tags: It includes provisions for "grandfathered" tags, which are tags from earlier standards that do not conform to the new structure but are still recognized for backward compatibility.
- Language Prioritization: The specification outlines how to handle language prioritization when multiple language tags are used.
- Deprecation and Registration: Mechanisms are provided for deprecating old tags and registering new ones, ensuring the system remains current with linguistic evolution.
Structure of Language Tags
Language tags in RFC-5646 are structured as follows:
- Language Subtag: A primary language identifier (e.g., "en" for English).
- Script Subtag: Optional, denotes the writing system (e.g., "Latn" for Latin script).
- Region Subtag: Optional, specifies the geographic region or country (e.g., "GB" for Great Britain).
- Variants: Additional tags for specific dialects or usage variations.
- Extensions: For private or special use, allowing for additional information not covered by the standard tags.
Applications
RFC-5646 is widely used in:
- Web technologies like HTML5 for specifying the language of web content.
- HTTP headers to indicate the language of resources.
- User interfaces for language selection.
- Content negotiation in web services and applications.
Evolution and Updates
Since its publication, RFC-5646 has seen updates to address emerging needs:
- RFC-5646 Updates: Subsequent RFCs like RFC-6067 have introduced additional subtags and extensions.
- BCP 47: RFC-5646 is part of BCP 47 (Best Current Practice 47), which is the overarching document for language tags.
External Links
Related Topics