I am trying to build a Validate As regex for telephone numbers (specifically that they only contain numbers and notation elements - i.e. not characters and not tabs etc) - so I tried first with /[\d ().-]/ and that didn't work even though when I test it at Regex101.com it validates correctly.
After some head scratching and testing and validating (because I find regex hard), I then went to first principles and cut and paste the example expression from p173 of the User Guide
/\\(?\\d{3}\\)? ?\\d{3}[-.]\\d{4}/
And something peculiar happened, the Create button on my form suddenly becomes disabled.
Which makes me wonder if my regex was ok to start with or whether there is a problem with Validate As regex?