[XQuery full text] i18n core comment: xs:language vs. xml:lang

Comment from the i18n review of:
http://www.w3.org/TR/2007/WD-xpath-full-text-10-20070518/

Comment 5
At http://www.w3.org/International/reviews/0706-xquery-fulltext/
Editorial/substantive: S
Location in reviewed document:
3.3.6
xs:language vs. xml:lang

Comment:
 
You write:
 
The StringLiteral following the keyword language designates one language. It must be castable to \"xs:language\"

 
We propose to use the data type definition for xml:lang [http://www.w3.org/2001/xml.xsd] instead of xs:language, that is: a union type of xs:language and the empty string. The empty string is necessary to express that no language information is associated with the content. This can be useful to trigger e.g. language-independent tokenization.