Tags for Identifying Languages

This specification has been revised 5 times since RFC 1766 (1995). Each document below formally obsoleted the one before it; the versions still in force are listed first.

Revision timeline

RFC 1766 (1995)
RFC 3066 (2001)
RFC 3282 (2002)
RFC 4646 (2006)
RFC 4647 (2006)
RFC 5646 (2009) ✓

Current versions — implement against these

RFC 3282Content Language HeadersCurrent
May 2002draft standard
RFC 4647Matching of Language TagsCurrent
September 2006best current practice
RFC 5646Tags for Identifying LanguagesCurrent
September 2009best current practice

Superseded versions — historical reference only

RFC 1766Tags for the Identification of LanguagesObsoleted
March 1995proposed standardreplaced by RFC3066, RFC3282
RFC 3066Tags for the Identification of LanguagesObsoleted
January 2001best current practicereplaced by RFC4646, RFC4647
RFC 4646Tags for Identifying LanguagesObsoleted
September 2006best current practicereplaced by RFC5646

This lineage is derived automatically from the “obsoletes” relationships recorded in the public RFC Editor index — no editorial judgement is applied to the ordering. The most recent document in the chain is RFC 5646 (September 2009).