hiding back cancel exit buttons in selection screen GUI status

*&---------------------------------------------------------------------*
*& Report  YSAP_HIDE_MENUS_SELSCREEN
*&
*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*

REPORT  ysap_hide_menus_selscreen.

DATA: it_ucomm TYPE TABLE OF sy-ucomm.

SELECTION-SCREEN BEGIN OF BLOCK b1 WITH FRAME.
PARAMETERS: pernr TYPE pa0002-pernr.
SELECTION-SCREEN END OF BLOCK b1.

AT SELECTION-SCREEN OUTPUT.
  APPEND :
  'E'    TO it_ucomm,  "for back
  'ENDE' TO it_ucomm,  "for exit
  'ECAN' TO it_ucomm.  "for cancel

 
  CALL FUNCTION 'RS_SET_SELSCREEN_STATUS'
    EXPORTING
      p_status        = sy-pfkey
*     P_PROGRAM       = ' '
    tables
      p_exclude       = it_ucomm.