Primitive Types

The primitive types defined in the OCL standard library are Integer, Real, String and Boolean. They are all instance of the metaclass Primitive from the UML core package.
 

Real

The standard type Real represents the mathematical concept of real. Note that Integer is a subclass of Real, so for each parameter of type Real, you can use an integer as the actual parameter. Real is itself an instance of the metatype Primitive (from UML Core).
 

Integer

The standard type Integer represents the mathematical concept of integer. Integer is itself an instance of the metatype Primitive (from UML Core).
 

String

The standard type String represents strings, which can be both ASCII or Unicode. String is itself an instance of the metatype Primitive (from UML Core).
 

Boolean

The standard type Boolean represents the common true/false values. Boolean is itself an instance of the metatype Primitive (from UML Core).