Questioned paths

? includes both zero- and one-occurrence alternatives. Variables introduced by the segment are null on the absent branch.

MATCH p = (a {name: 'Alice'})(-[edge:Knows]->(maybe))?(destination)
RETURN maybe.name AS optional_stop, destination.name AS destination
ORDER BY destination;

This returns an absent segment ending at Alice and a present segment ending at Bob. Unlike OPTIONAL MATCH, the zero-occurrence result remains even when a one-occurrence match exists.

? also differs from {0,1}: questioned declarations are nullable singleton values, whereas quantified declarations are lists. Conditional singletons cannot be implicitly reused within the same MATCH. They can be read by expressions; a later MATCH applies ordinary bound-element identity constraints.