Maximum value cardinality is a constraint on the number of values to which a binary relation can map a domain instance. It restrict the relation to AT MOST N values for a given a domain instance. A cardinality of 0 means that the relation does not hold for that instance.
(Nth-Domain Maximum-Value-Cardinality 3 Nonnegative-Integer) (Nth-Domain Maximum-Value-Cardinality 2 Binary-Relation) (<=> (Maximum-Value-Cardinality ?Instance ?Binary-Relation ?N) (And (Binary-Relation ?Binary-Relation) (Nonnegative-Integer ?N) (=< (Value-Cardinality ?Instance ?Binary-Relation) ?N)))