If an actual argument is a procedure, its corresponding dummy argument is a dummy procedure.
Dummy procedures can appear in function or subroutine subprograms.
The actual argument must be the specific name of an external, module, intrinsic, or another dummy procedure. If the specific name is also a generic name, only the specific name is associated with the dummy argument. Not all specific intrinsic procedures can appear as actual arguments. The actual argument and corresponding dummy procedure must both be subroutines or both be functions. If the interface of the dummy procedure is explicit, the type and kind parameters, and rank of the associated actual procedure must be the same as that of the dummy procedure.