10. The method of claim 9 , wherein the number-valued expression is an XQuery expression evaluated in the context of an Extensible Markup Language (XML) document that specifies the values of the attributes of the data provider.
9. The method of claim 8 , wherein the specification of a mapping from an assignment of values for attributes of a data provider to a numeric value comprises a number-valued expression in which the names of the attributes of a data provider appear, representing the assigned values of the attributes.