[xacml] functions and predicates

I think we need to clarify two dimensions of this decision:

1. Standard (XACML-defined) operations versus
   policy-writer-defined operations.

2. Type of operation
     Boolean (output=Boolean, args=Boolean)
       Examples: AND, OR, NOT, ORDERED-AND, N-OF
     Relations (output=Boolean, args=various)
       Examples: GreaterThan, Equals, SubsetOf
     Functions (output=various, args=various)
       Examples: DateDuration, DateAdd, IntegerAdd, StringToUpper
     Conversion Functions (output=various, args=various)
       These are invoked implicitly by the PDP if the input
       provided in the request is of a different type than the
       argument type specified by the Function or Relation
       Examples: StringToInteger

-- 
Anne H. Anderson             Email: 
Sun Microsystems Laboratories
1 Network Drive,UBUR02-311     Tel: 781/442-0928
Burlington, MA 01803-0902 USA  Fax: 781/442-1692