Use of FIELD-SYMBOLS when there is no option to set/change value in EXIT

Let’s say you have a requirement to update the KNA1-AUFSD (Order Block) whenever any customer created.

You have customer exit (function) EXIT_SAPMF02D_001.

But here we have KNA1 in the IMPORTING parameter only not in TABLES or CHANGING.

So in this case we can use field-symbols like below:

FIELD-SYMBOLS: <AUFSD> TYPE ANY.

DATA: KNA1_AUFSD(20) VALUE '(SAPMF02D)KNA1-AUFSD'.

* Write your condition here.

IF SY-TCODE+2(2) = '01'.
  ASSIGN (KNA1_AUFSD) TO <AUFSD>.
  <AUFSD> = '01'.
ENDIF.