References in Attribute filtering

[Rod Widdowson]

> >Did we come to the conclusion that we should not support
> >"PolicyRequirementRuleReference", "AttributeRuleReference",
> >"PermitValueRuleReference" and "DenyValueRuleReference"?
> 
> My hope was that we could support some of it to allow reusing policies,
> but if it's work, I guess we can table it.

There is stuff there.  It is (as I remember incomplete) and might be
difficult to document.   It is such a cool idea and would be helpful that I
too would be loth to jettison it.

I'll take the "difficult to document" bit as a challenge and see what I can
do.  Writing the documentation will also flush any eventual bugs (I happened
upon it because it is light for testing).

R