Use of xml:lang versus xs:language

Prompted by something that I saw in the Dublin Core discussion, I noticed
the definition of an attribute that is a reference to xml:lang.

If I intend to provide 0..unbounded Description elements, each with a
corresponding language attribute (reflecting the language of the
Description's text), I could represent it as:

	<xs:attribute ref="xml:lang"/>

or as 
	<xs:attribute name="lang" type="xs:language"/>

Is there any meaningful difference between the two? What are the relative
merits of each approach?

Thanks

Mark


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Mark Feblowitz                                   [t] 617.715.7231
Frictionless Commerce Incorporated     [f] 617.495.0188 
XML Architect                                     [e]
mfeblowitz@frictionless.com
400 Technology Square, 9th Floor 
Cambridge, MA 02139 
www.frictionless.com