>Your grammar clearly does not preclude extra stuff at the end of the > string and you do not specify that the string must be completely > consumed.
Thanks for the answers received so far. The /\D/ after Criteria:zoekVraag was a typo, /\Z/ was intended; sorry for that. Experimenting so far with your solutions, it seems that completely consuming the string is the answer. Adding 'eostring' after basisZoekVraag (operator basisZoekVraag)(s) and defining eostring as /\Z/ results in the behaviour I want. I'm new to this kind of stuff, so your help was appreciated. Peter
