SUBROUTINE USER_INTERFACE_INIT()
      
      RETURN
      END
      
      SUBROUTINE USER_INTERFACE_SHUTDOWN()
      
      RETURN
      END
      
      SUBROUTINE SYSTEMCOMMAND(param)
      
#include "dyna.inc"
#include "par.inc"
      RECORD /COMMAND_PARAM/ param
      
      STOP '<NULL system command called>'
      RETURN
      END