How Do I use -reg cheat?

[luizgsa16]

I'm using JJ cheat pack and would like to know what -reg does.
And how do I use it please be very specific

[JJ2197]

just say -reg <color/kill>
For example
-reg kill
Then you click anywhere then click up and right from the other click
this will make a region that will kill any unit that enters it...

[luizgsa16]

do i right click or left click? i think i got it to work but i still dont understand it like it only does it to a very small area

[JJ2197]

Right-click and you need a unit selected... It makes an area from
the first point you click to the second one...

Also I've updated my cheatpack so that it doesn't matter where you
click, so down left to up right and up right to down left will both work...