​@Mark Thompson are you able to confirm which version of Nintex Forms and which control you are using? You mentioned you were able to validate using regular expression but it wasn’t clear what the difference was to the one that isn’t working.

HI ​@leighburke ,  I believe this is what we are using: Nintex Forms for SPFx / Office 365 – Enterprise Subscription according to the enterprise dashboard. This is the control I’m using

Cheers

Mark

​@Mark Thompson Unfortunately, I am not aware of any way to do this out of the box using the text long control type.  As input validation using a regular expression is only available on the text short control. The closest option ootb would be doing validation based on the number of characters. Alternatively you could log a feature request(https://ideas.nintex.com/). It might also be possible build a plugin that could achieve this, i have not heard of any existing plugins to do this.