This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
What languages is an implementation required to support? Is it an error if it enounters a language option that it doesn't implement? Proposal: Implementation-defined. Note this in Section 3.2.6 and (therefore) in appendix I.
The WG agreed to add a sentence: If a language identifier is not supported then the behavior is implementation-defined. If the implementation chooses to raise an error, it raises [err:FTST0009].