From: Oskar Welzl <oskar.welzl@pan.at>
>
> Christian,
>
> > If @hreflang keeps to be just meta informational, hreflang="de, en, fr,
tr" 
> > could be ambiguous: A document is available in 4 variants or the
document 
> > contains four languages... - not a bad ambiguity at all.
>
> as i said at the very beginning, with @hreflang being meta-information
only,
> I'd much prefer it to have one value only. i think listing multiple
values in one
> attribute is not good XML. it complicates further generic processing
> (XSL-transformations etc.) by applications not aware of the XHTML syntax.

I'll have to disagree with both of you here.  Suppose a document were
available in English, German, and a bilingual version.  It would be useful
to be able to specify hreflang ="de,en" and have it mean that the resource
is supposed to be the bilingual document. If the intent is supposed to be
any of the three possibilities, then we would need something like
hreflang="de en de,en".  However, as I have stated previously, because
metainfo attributes like hreflang are most useful for non-negotiating
protocols such as FTP that do not provide any metainfo, I am strongly
in favor of making them all single valued.  However, in this case, the
listing
of multiple languages IS a single value indicating that all the languages
occur in the resource, not that versions in each language exist.