Need to have language information data category as a feature at risk?

Hi all,

I wonder if we should mark the language information data category as a
feature at risk.

At
http://www.w3.org/International/its/itstagset/itstagset.html#langinfo-definition
, it says:

[[The element  langRule  is used to express the language of a given piece
of content. The  langPointer  attribute points to the markup which
expresses the language of the text selected by the selector attribute.
This markup MUST use values that conform to [RFC 4646] or its successor.
The recommended way to specify language identification is to use xml:lang.
]]

I am worried about the MUST: Will anybody provide implementations which
process the value mentioned? If not, at least this MUST should be a
feature at risk

A - minor, but important - issue: I think we don't yet have the xml:lang
declaration as part of the non-normative XML Schema and the generated DTD.
In the XML Schema, we need s.t. like
<xs:import namespace="the xml namespace" schemaLocation="schema which
contains xml:lang declaration"/> .

Felix