Coding "Required If" in Studio

I'm feeling a little silly this afternoon, and apparently my brain isn't functioning as it should.  I'm looking for the guide on coding the "Required If" function and can't seem to find it.

Here's what I need to do: Set a field as Required If a Date Field is not empty.

Specifically, I need a Text Field set as Required if a Date is entered in a date field.

Will someone be gentle with me and help me code this in Studio please?