[xacml-comment] Section A12

I'm finding section A12 difficult to understand. I think the information 
could
be more clearly presented.

1) It introduces the Target element and its immediate child elements, and
then the standard functions that can be used for a MatchID. But then a
couple of paragraphs later it says that the only functions that can appear
in a MatchID of a Target child are a different bunch of functions. This is
confusing.

2) <i>type</i>-match appears as a standard function. (And does not appear
in the conformance tables.) The subsequent paragraph starts "The evaluation
semantics for a match is as follows...' But is this referring to the 
standard
match functions as a whole, or just the behaviour of the <i>type</i>-match
function itself. If not then where's the definition of <i>type</i>-match ?

3) The text and the examples refer to the special match functions before
they've actually been defined.

I think a reorg of section A12 would improve the legibility quite a bit.

John