Instead of applying/changing code of 'user-exit' ABAPs ZXRSAUnn or ZXRSRUnn, you can also use BADI
RSU5_SAPI_BADITcode SE18:

Implementation --> Overview or Implementation --> Create
Double click on METHOD: DATA_TRANSFORM

Within METHOD
IF_EX_RSU5_SAPI_BADI~DATA_TRANSFORM the required user exit code can be entered/altered.