What is the correct and alternative way to (post) action on "Purchase Order Subform"?

hi…
I want help, I want to put a procedure to check an input value (whether it was entered or not) on Action (Post), and on “Purchase Order Subform” but it gives me an error because (Post) Action is not found(or included) in “Purchase Order Subform”.

What is the correct and alternative way to (post) action on “Purchase Order Subform”?

Hi, you can use TESTFIELD to check if data is entered.

You can subscribe to an event OnPost if a field has value or not. Add your logic that way.