RE: [Ltru] Re: Remove extlang from ABNF?

> >language      = (2*3ALPHA [ extlang ]) ; shortest ISO 639 code
> >               / 4ALPHA                 ; reserved for future use
> >               / 5*8ALPHA               ; registered language subtag
> >
> >extlang       = *3("-" 3ALPHA)         ; OBSOLETE (do not use)

> <chair hat off>
> I would be okay with this, with some explaining text.

What do we expect OBSOLETE to do?  Ok, I get that I shouldn't use the obsolete tag to encode new data, but are applications expected to recognize such obsolete tags, even if they weren't ever valid?

If applications aren't expected to recognize them, then why declare it formally?  Why not just say in the prose that there use to be such an extlang thought, but its obsolete?  If someone reading RFC3066bis is really curious they could look at RFC3066 and see what the original idea was.

My concern is that if a developer/spec writer/tester is reading this they might feel that its best to go ahead and decide to recognize these in case any of these obsolete tags are encountered.  That could require a considerable expense depending on the depth of the effort.  If it were clear that none have ever been registered or legally allowed, and it was obsoleted before it was ever implemented, then the hypothetical development team could save that expense and effort.

- Shawn

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