Three state decision-box

Three state decision-box

Hi,
if i use a decision box field in a form and make it mandatory, i can submit the form only if i flas as true.
I thinks that is better to make it with three state, true (V), false (X) and null(-) if i make it mandatory cause of a mandatory decision box is useless if i can use only true value.
If i need to use it as "accept condition" case, i can use a validation workflow to validate it's true value, but if i need only to ask my user if he want, or not want, to trigger some flow i'm forced to use a mandatory select with YES/NO values.

Salvatore