Multiplicity constrain the number of values that may be contained by a container (ie entity set)
The multiplicity specifies valid cardinalities of the collection it represents. (It denotes the possible cardinalities values of the collection)
The multiplicity is a constraint on the cardinality, which shall:
- not be less than the lower bound
- and not greater than the upper bound specified (unless the multiplicity is unlimited (ie *), in which case there is no constraint on the upper bound).
The properties applied to the collection of the container element.
- lower bound
- upper bound
- order (ordered or not) - ie the elements can be inserted/retrieved in a specific order
- unique (is unique or not) - ie does not allow duplicate
The collection type properties defines the type of collection.
- A Multiplicity that is not multivalued can represent at most a single value
- Infinity upperbound symbol: *