FILTER (?z)?

Hi,

I'm writing a Prolog parser for SPARQL based on the latest document
(April 6).  Aim is to provide SPARQL support on top of the SWI-Prolog
semantic web libraries, but first some work to do ...

To get the grammar debugged I'm using the SyntaxDev test-sets.  I
understand they have no formal meaning and are not approved.  Still,
I'd expect them to be mostly correct and there are only few syntax
tests in the rest of the test-set.

I've trouble with the test 'syntax-keywords-01.rq':

================================================================
SELECT *
WHERE { ?x FILTER:foo ?z FILTER (?z) }
================================================================

FILTER allows for a bracketed expression and function calls, but reading
through the syntax this only allows for relation expressions. Skimming
the rest of the document, I have the impression the "FILTER (?z)" is 
illegal.  Am I right?

	Cheers -- Jan