Strong Typing is the enforcement of type conformance. The object types defined by classes and interfaces are analogous to the built-in primitive types of the language. Object types are identified using an object type name that includes the name of the class or interface. For a user-defined class or interface, this name matches the file name of the file that stores the definition of the class or interface type.
Strong types defined by a programmer are enforced by the compiler for conformance to a specific Class definition. Among other benefits, this allows checking many possible errors at compile time instead of discovering them at run time.
For more information on Object-oriented programming, see the guide OpenEdge Development: Object-oriented Programming.