How to make one field mandatory in Enterprise Portal -> Web Control

Using Ax2009.

In web control ‘PurchReqTableInfo.ascx’ I have to make one field mandatory(marked with red asterisk).

How can I make my field mandatory?

It might be too late, but in case someone reaches this thread, just add the property “Mandatory” set to true in the field(s) in the .ascx file, and that’s it.