xml-dev - checking regular expressions in patterns

[David Valera <dvalera@pcl-hage.nl>]

hello,

A few months ago someone posted here a webpage where you could insert a
regular expression in one field, and in another field you could only type
whatever the regular expression allowed you to. I have been looking for this
posting, but I am unable to find it back. Does anyone remember wich webpage
this was?

TIA

David Valera