A location is a rectangle on the map. Bring always tests against one, and unit creation and movement are addressed by one.
The key action is Move Location, which snaps a location onto a chosen unit. That is what gives you “around this unit”, and skill ranges, tracking and proximity checks are all built on it.
MoveLocation("Skill Area", "Terran Marine", CurrentPlayer, "Anywhere");
KillUnit("Men", P8, "Skill Area");If several triggers move the same location they will overwrite each other. Make a separate location per purpose; it is much safer.