Question : Main Form - Sub Form

I would like to automatically fill some fields of a sub form after updating a field on a main form.
The fields are not links fields.
I would simply like to........
If fieldA on main form is not blank then
fieldA on subform = x, field b on subform is = y, field c on subform = z etc

Answer : Main Form - Sub Form

you can refer to the subform control with this syntax

me.subformName.form.controlName=me.controlName