1.2. Notation of a quantifier
The following table describes the explicit forms of a quantifier:
occurs n exactly n occurrences
occurs m..n minimum m occurrences, maximum n occurrences
occurs n..* minimum n occurrences, maximum unlimited
Alternative notations:
occurs required exactly one occurrence (occurs 1)
occurs optional zero or one occurrence (occurs 0..1)
occurs ? zero or one occurrence (occurs 0..1)
occurs * unlimited occurrence (occurs 0..*)
occurs + one or more occurrences (occurs 1..*)
Note since the default value of the quantifier is "required" it may
be omitted. E.g.:
ISBN="required int(10000000, 999999999)"
can be written as
ISBN="int(10000000, 999999999)"