(1) Linguasphere Observatory / Observatoire Linguistique, Hebron, Wales SA34 0XT: dalby@linguasphere.com; (2) Department of Computing, University of Surrey, Guildford GU2 7XH: l.gillam@surrey.ac.uk; (3) British Standards Institution (BSI), London W4 4AL; christopher.cox@bsi-global.com; (4) ICT Marketing Ltd, Haverfordwest, Wales SA61 1BW: md@ictmarketing.co.uk

The international community, including the International Organization for Standardization (ISO), is currently seeking more granular systems of language identifiers than the widely used tags of ISO 639 parts 1 and 2. There is growing need for the more precise identification and annotation of language-based resources. This paper presents a key response to this need, in which the Linguasphere Register of the World's Languages and Speech Communities would provide the referential framework for a future part 6 of ISO 639. The paper discusses the proposed evolution of ISO 639-6 and its relationship to other parts of ISO 639, including its relevance to the definition of meta-data categories in ISO 12620.