At the moment a working group at the W3C to create a query language for XML databases or documents. 

The current work can be found at:
http://www.w3.org/XML/Query

XQuery, as it is commonly called, is a kind of SQL for XML data(bases). It is tightly connected to [XPath] 2.0 and [XSLT] 2.0.

At the moment no Tcl implementation exists, partially because XQuery uses XML Schema Validation extensivly. It would probably be quite easy to provide a Tcl interface to a XQuery engine like Saxon [http://saxon.sf.net] or Galax [http://db.bell-labs.com/galax/].

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[Category XML]