[xacml] Review of Obligations Section 5.32

I think we should take out the "semantic" definitions on the fulfillment
of Section 5.32 Obligations in this element definition. (i.e. in this
section).

Namely, change the sentence "The FulfillOn attribute SHALL indicated the
decision value for which this obligation MUST be fulfilled." to

The FulfillOn attribute SHALL indicated the effect for which this
obligation applies.

FulfillOn [required]

The effect for which this obligation applies.


The fulfillment of obligations is taken care of in the Chapter 7.