Match modes

DIFFERENT EDGES prevents the same edge identity from being used by multiple edge occurrences in one MATCH, including disconnected paths. It is the current default.

MATCH DIFFERENT EDGES (a)-[first:Knows]->(b)-[second:Knows]->(c)
RETURN a.name AS start, c.name AS destination;

REPEATABLE ELEMENTS permits reuse at the MATCH level:

MATCH REPEATABLE ELEMENTS p = WALK (a {name: 'Alice'})-[:Knows]-{1,3}(b)
RETURN b.name AS destination, PATH_LENGTH(p) AS hops ORDER BY hops, destination;

The singular spellings DIFFERENT EDGE and REPEATABLE ELEMENT are accepted. Every new MATCH starts a new reuse scope. A path mode adds its own constraints even under REPEATABLE ELEMENTS.

The default is an implementation compatibility choice, pending a complete normative GQL audit. Multiple paths using selective prefixes in a DIFFERENT EDGES clause are currently rejected: cross-path uniqueness and selection cannot safely be applied in an arbitrary order.