SUBMODULE (ModMain : SubMod1) SubMod2

    !   This submodule contains implementation of 'Proc_Main_II' routine.

    IMPLICIT NONE       ! Enforce explicit typing of all variables
    
    ABSTRACT INTERFACE
        !----------------------------------------------------------------------
        FUNCTION Proc_CB_ABST2(ByteArr, Offset) RESULT(Res)
            !^ an abstract procedure for callback routines.
            IMPORT
            INTEGER(KIND=1), INTENT(IN) :: ByteArr(0:)
            INTEGER,         INTENT(IN) :: Offset
            INTEGER(KIND=8)             :: Res
        END FUNCTION Proc_CB_ABST2
        !----------------------------------------------------------------------
    END INTERFACE

    CONTAINS

    !**************************************************************************
    MODULE FUNCTION Proc_Main_II(Input, Algo) RESULT(Output)
        ! main procedure II.
        ! arguments
        INTEGER(KIND=1), INTENT(IN) :: Input(:)
        INTEGER,         INTENT(IN) :: Algo
        INTEGER(KIND=8)             :: Output
        ! execution
        SELECT CASE (Algo)
        CASE (1)
            Output = Proc_Engine_II(Input, Proc_CB_I)
        CASE (2)
            Output = Proc_Engine_II(Input, Proc_CB_II)
        CASE (3)
            Output = Proc_Engine_II(Input, Proc_CB_III)
        END SELECT
        RETURN
    END FUNCTION Proc_Main_II
    !**************************************************************************
    FUNCTION Proc_Engine_II(Input, ProcCB) RESULT(Output)
        ! working procedure II.
        ! arguments
        INTEGER(KIND=1), INTENT(IN) :: Input(:)
        PROCEDURE(Proc_CB_ABST)     :: ProcCB
!        PROCEDURE(Proc_CB_ABST2)     :: ProcCB
        INTEGER(KIND=8)             :: Output
        ! execution
        Output = ProcCB(Input, 0)
    END FUNCTION Proc_Engine_II
    !**************************************************************************

END SUBMODULE SubMod2