SAP ABAP Message Number LOP - 018 (LOP) is used by

• Class (1)

#	Object Type	Object Name	Object Description	Package	Structure Package	Software Component
1	Class	CL_LOP_LIST_MASTER Method: IF_LOP_LIST_MASTER~SET_EXT_REF	Option list as master data	LOOP	APPL	SAP_APPL