I can't seem to find any information on the formatting of a custom validation pattern rule?

I have a serial number I want to validate. It starts with three letters "DSN" which are always the same and then followed by 5 numbers. So basically DSNxxxxx. But I can't find any information on how the fields should work for setting up the pattern. There is nothing in the documentation.

Thanks
Baub

Hello Baub,
As the help text explains, in the pattern validation field you should use a valid regular expression.