Checking is there any UserExit attached ?

This program is for checking UserExit attached in a tcode.
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REPORT ZARSTEST .
TABLES : tstc, tadir, modsapt, modact, trdir, tfdir, enlfdir.
TABLES : tstct.

DATA : jtab LIKE tadir OCCURS 0 WITH HEADER LINE.
DATA : field1(30).
DATA : v_devclass LIKE tadir-devclass.

PARAMETERS : p_tcode LIKE tstc-tcode OBLIGATORY.

SELECT SINGLE * FROM tstc WHERE tcode EQ p_tcode.
IF sy-subrc EQ 0.
SELECT SINGLE * FROM tadir WHERE pgmid = 'R3TR'
AND object = 'PROG'
AND obj_name = tstc-pgmna. "'SAPLITO0'.
MOVE : tadir-devclass TO v_devclass.
IF sy-subrc NE 0.
SELECT SINGLE * FROM trdir WHERE name = tstc-pgmna.
IF trdir-subc EQ 'F'.
SELECT SINGLE * FROM tfdir WHERE pname = tstc-pgmna.
SELECT SINGLE * FROM enlfdir WHERE funcname = tfdir-funcname.
SELECT SINGLE * FROM tadir WHERE pgmid = 'R3TR'
AND object = 'FUGR'
AND obj_name EQ enlfdir-area.
MOVE : tadir-devclass TO v_devclass.
ENDIF.
ENDIF.
SELECT * FROM tadir INTO TABLE jtab
WHERE pgmid = 'R3TR'
AND object IN ('SMOD', 'SXSD')
AND devclass = v_devclass.
SELECT SINGLE * FROM tstct WHERE sprsl EQ sy-langu AND
tcode EQ p_tcode.

FORMAT COLOR COL_POSITIVE INTENSIFIED OFF.
WRITE:/(19) 'Transaction Code - ',
20(20) p_tcode,
45(50) tstct-ttext.
SKIP.
IF NOT jtab[] IS INITIAL.
WRITE:/(95) sy-uline.
FORMAT COLOR COL_HEADING INTENSIFIED ON.
WRITE:/1 sy-vline,
2 'Exit Name',
21 sy-vline ,
22 'Description',
95 sy-vline.
WRITE:/(95) sy-uline.

LOOP AT jtab.
SELECT SINGLE * FROM modsapt
WHERE sprsl = sy-langu AND
name = jtab-obj_name.
FORMAT COLOR COL_NORMAL INTENSIFIED OFF.
WRITE:/1 sy-vline,
2 jtab-obj_name HOTSPOT ON,
21 sy-vline ,
22 modsapt-modtext,
95 sy-vline.
ENDLOOP.

WRITE:/(95) sy-uline.
DESCRIBE TABLE jtab.
SKIP.
FORMAT COLOR COL_TOTAL INTENSIFIED ON.
WRITE:/ 'No of Exits:' , sy-tfill.
ELSE.
FORMAT COLOR COL_NEGATIVE INTENSIFIED ON.
WRITE:/(95) 'No User Exit exists'.
ENDIF.
ELSE.
FORMAT COLOR COL_NEGATIVE INTENSIFIED ON.
WRITE:/(95) 'Transaction Code Does Not Exist'.
ENDIF.

AT LINE-SELECTION.
GET CURSOR FIELD field1.
CHECK field1(4) EQ 'JTAB'.
READ TABLE jtab with key obj_name = sy-lisel+1(19).
IF jtab-object = 'SMOD'.
SET PARAMETER ID 'MON' FIELD sy-lisel+1(10).
CALL TRANSACTION 'SMOD' AND SKIP FIRST SCREEN.
ELSE.
SET PARAMETER ID 'EXN' FIELD sy-lisel+1(19).
CALL TRANSACTION 'SE18' AND SKIP FIRST SCREEN.
ENDIF.

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[Copy from one of my senior colleague, many Thanks ! ]