How To Do Validation Check on A Custom/Standard Field in CRM Web UI

Hi All,

I have some requirements here, We need to put a validation check for a field that we have on the Web UI screen.

Scenario:

1. I have a field in the Web UI, let's say a text box, type CHAR5

2. I want to validate that at all times, the content of that field need to be 5 characters strictly

How can this be achieved? anyone can enlighten me a bit?

Best Regards

Andre Julius