Hello Shardul:
Maybe you can try this way:
Tcode: CMOD --> Create new project(Z*) --> Assignments enhancements:PBAS0001
--> EXIT_SAPFP50M_001 --> ZXPADU01,
Add below code:
IF INNNN-INFTY = '0021'.
IF INNNN-SUBTY = '11'.
INNNN-DATA1+18(1) = '1'.
ELSEIF INNNN-SUBTY = '12'.
INNNN-DATA1+18(1) = '2'.
ENDIF.
ENDIF.