Setting type variables to Null

this works:

Type TFood
	Field Amount:Int
End Type

Type TAnt
	Field Food:TFood = New TFood
	Method check()
		If Food Then Print "not null" Else Print "Null"
	End Method
End Type

Global m:TAnt= New TAnt

m.check()
m.Food=Null
m.check()

is that essentially what you are trying to do?