In D&D 5e, the spell Dispel Magic says
Choose one creature, object, or magical effect within range.
The rest of the spell description explains that spells "on the target" of a level lower than that at which Dispel Magic was cast automatically end, and those of a higher level require a check.
This makes perfect sense when targeting creatures or objects which may have spells on them. But what does it mean to target a magical effect?
Does it mean that you can choose to target just one specific ongoing spell effect instead of stripping the whole shebang (clearing a negative spell from an ally with positive spells also in place, or a positive spell from an enemy who is under attack from a negative spell)?
Or, is this only for the special case of certain spells (like Imprisonment) which have effects which specifically mention being targeted by Dispel Magic, and since no effect is described otherwise? (This is a literal reading: a spell is a magical effect, but does not have spells on it, so the Dispel Magic effect has nothing to act on.)
Or — and I think this is a stretch — can magical effects which are not spells be dispelled by Dispel Magic? If so, what are the mechanics?