Set operations in XACML

["Daniel Engovatov" <dengovatov@bea.com>]

Minor proposal:

It seems that provided set operations in the specifications are
incomplete, as they do not provide a way to do difference of sets.

I suggest that we add "type-except" (or type-difference, I slightly
prefer except for being used in some other places) with a description:

"This function SHALL take two arguments that are both a bag of type
values. The expression SHALL return a bag of type such that it contains
all elements that are in the first argument that are not in the second
argument. No duplicates as determined by
"urn:oasis:names:tc:xacml:1.0:function:type-equal" SHALL exist in the
result."

A use case would be to remove a particular value(s) from a bag/set.

Daniel;