key reference

I mentioned on the call today that I had previously posted something
about key attributes, but it turns out it was in a different context.

Today's discussion was around unique identifiers for resources or
subjects in a XACML request.  My post was about identifying decisions
returned from a multi-decision request.

http://lists.oasis-open.org/archives/xacml/200910/msg00019.html

It might be useful to address the general topic of keys in XACML, in
order to provide a uniform, flexible mechanism for identifying things
uniquely and reliably in all components of a XACML system.  The current
"resource-id", "subject-id", and "action-id" attributes could serve this
purpose, but are not specified for this task.  They are also of limited
use for entities that can only be uniquely identified using more than
one attribute.

--Paul