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).