While all of these missions tend to share an end goal, they usually play out as shortened Garden / Graveyard Ops games with players defending a base until a boss or special enemy wave appears and the item required for the mission is recovered.
op., at p. 8: «As we said in Caballes and reiterate today, a traffic stop «prolonged beyond» [the amount of time reasonably required to complete the stop's mission] is «unlawful».»