Like I said, I dont know Unity Pro.
But, I think that what mosama and GeoffC calls "defining variables" are two different things.
In S7 SCL (and the other languages) you create UDTs, DBs, FCs and FBs wherein you have variable declarations.
In Unity Pro ST, you can create a global variable via a shortcut function without leaving the editor (at least thats what I figure out from GeoffC's input).