parts of TREX for generic matching

I was talking to Uche Ogbuji today about RDF inference languages and the
topic came up of how to express complex matches.

It occurred to me that TREX provides a good framework for generic matching.
If you look at the patterns:

	the following are specific to validating XML (matching requires a
notion of attributes and child elements):

		- element
		- attribute
		- empty
		- anyString
		- string
		- data
		- mixed
		- group
		- interleave
		- oneOrMore
		- zeroOrMore

	whereas the following are generic matching constructs:

		- notAllowed
		- optional
		- choice
		- concur
		- grammar
		- ref
	(and we can add difference here)

If one introduces the notion of an ordered sequence, one can move the
following patterns across to being generic:

		- group
		- interleave
		- oneOrMore
		- zeroOrMore

Furthermore, if conditions on string matching are relaxed (no pun intended)
one can use the generic constructs plus the following to do string regular
expressions:

		- anyString
		- string
		- data

I just thought I'd throw these idea out to the TREX TC. If nothing else, I
might write up a spec on generic matching constructs that borrows heavily
from TREX.

James