Typing means defining a generic or complete data type for a formal parameter of a procedure or a field symbol. In contrast to data objects where the data type has a specific property and is always known fully, formal parameters and field symbols receive their data type only upon transfer of a current parameter when a procedure is called or when a memory area is assigned using ASSIGN.
Through the typing of formal parameters or field symbols (see syntax of typing), some or all type properties are defined already before the actual definition of the type. This allows formal parameters and field symbols to be implemented that require certain type properties. During the assignment of an actual parameter to a formal parameter or a data object to a field sumbol, the system checks whether its data type fits the typing.
The static type of data reference variables is always completely generic (data) or completely typed (see DATA - reference variables).