[rt-users] Custom Field Validation Question

[Mathew Snyder]

I've added to our development server one of the custom field validations
that was posted to the mailing list a while ago by Nick Metrowsky.  The
particular validation I've added is
'(?#DateDDMMYYYY)^(0[1-9]|[12][0-9]|3[01])[-/.](0[1-9]|1[012])[-/.](19|20)\d\d',

The question I have is whether or not I can make it optional as it will
only apply to tickets that involve delivery of things such as hardware
provisioning or application development.

Is there a way to validate the input only if there is something to
validate and ignore it if it is blank?


Thanks,
Mathew Snyder