Pattern Constraints

Pattern constraints in UML

A pattern constraint requires that a string attribute’s value must match a certain pattern, typically defined by a regular expression. For instance, for the object type Book we define an isbn attribute with the datatype String as its range. Then we add a pattern constraint requiring that the isbn attribute value must be a 10-digit string, or a 9-digit string followed by “X” to the Book class rectangle shown in the following diagram.