If a prototyped procedure has call parameters or a return value, then it must have a procedure interface definition. If a prototype has been specified for the procedure, the procedure interface definition is a repeat of the prototype information within the definition of a procedure. Otherwise, the procedure interface definition is used to implicitly define the prototype for the procedure. The procedure interface definition is used to declare the entry parameters for the procedure and to ensure that the internal definition of the procedure is consistent with the external definition (the prototype).
You specify a procedure interface by placing PI in the Definition-Type entry (positions 24-25). Any parameter definitions, indicated by blanks in positions 24-25, must immediately follow the PI specification. The procedure interface definition ends with the first definition specification with non-blanks in positions 24-25 or by a non-definition specification.
For more information on procedure interface definitions, see Procedure Interface.