Validation of values in the properties of the Feature

Hi,
I have an XFM project - OCM up3 + oracle 12.


How to check if the value (string) is unique?
In addition to uniqueness, I check the correctness of the entered value (XX-0000-00).
I am referring to functionality similar to isRequired, i.e. it does not allow the user to insert eg. a symbol when the required value is not entered.
Could I use Watcher here? 

I will be grateful for any kind of suggestion!

TIA
adek