Sometimes you'll have a room with blocked off areas where you don't want enemies to spawn. However, through player interaction, like pushing blocks, that room's area can become accessible later on, and you want enemies to be able to access it too at that point (so you can't use the "no enemy" flag there).
Would it be possible to have a "no spawn" flag to use in these situations, so enemies won't initially spawn on these combos, but may go there once the path has been opened?
I know you can work around this by using the enemy spawn flags in the rest of the room. You can even retain the randomness by placing the same enemy placement flag several times. However this is a bit more complicated than just telling ZC not to spawn enemies on certain combos.