Hi plz help me this question ASAP

Question

without writing start-of-selection-screen we can write end of selection screen and wise versa then what is the use.

Answer 1

The sequence in which the processing blocks occur in the program is irrelevant. The actual processing sequence is determined by the external events. However, to make your programs easier to understand, you should include the event blocks in your program in approximately the same order in which they will be called by the system. Subroutines should be placed at the end of the program.
Statements that are not assigned to a processing block are never executed. An exception to this are any non-declarative statements between the REPORT or PROGRAM statement and the first processing block, which are assigned to the default event
<b>START-OF-SELECTION</b> if a program does not contain an explicit <b>START-OF-SELECTION</b> block, these statements form the entire <b>START-OF-SELECTION</b> block. If a <b>START-OF-SELECTION</b> keyword is already included in your program, these statements are inserted at the beginning of this block. If the program does not contain any explicit event blocks, all non-declarative statements are assigned to the default processing block <b>START-OF-SELECTION.</b>
There can be many scenarios
<b>SCENARIO 1:</b>
REPORT  ZTEMP                                                       .
FORM ROUTINE.
  WRITE / 'Subroutine'.
ENDFORM.
WRITE / 'Statement 1'.
START-OF-SELECTION.
  WRITE / 'Statement 2'.
PERFORM ROUTINE. 
  WRITE / 'Statement 3'.
*END-OF-SELECTION.
This code wont give an error.
<b>SCENARIO 2:</b>
REPORT  ZTEMP                                                       .
FORM ROUTINE.
  WRITE / 'Subroutine'.
ENDFORM.
WRITE / 'Statement 1'.
START-OF-SELECTION.
  WRITE / 'Statement 2'.
  PERFORM ROUTINE. 
  WRITE / 'Statement 3'.
END-OF-SELECTION.
This wont give an error either, as both event blocks are present.
<b>SCENARIO 3:</b>
RITE / 'Statement 1'.
FORM ROUTINE.
  WRITE / 'Subroutine'.
ENDFORM.
*START-OF-SELECTION.
  WRITE / 'Statement 2'.
PERFORM ROUTINE.
  WRITE / 'Statement 3'.
END-OF-SELECTION.
This woul dgive an error, as start of selection is not present, and we use end of selection.
Hope this answers your question.
<b>Reward if helpful</b>