dunno, really. the boards aren't public yet so we won't really be answering questions until they are.
however, i believe the answer is
combatMode unit_name
which will return "BLUE" (Never fire), "GREEN" (Hold fire - defend only), "WHITE" (Hold fire, engage at will), "YELLOW" (Fire at will), or "RED" (Fire at will, engage at will).
dunno if that works with explicit "hold fire" instructions, but a quick experiment will tell you.