SAP ABAP Message Number FKKINV - 006 (FKKINV) is used by

• Class (6)

#	Object Type	Object Name	Object Description	Package	Structure Package	Software Component
1	Class	CL_FMCAINV_BAPIBILL Method: CHECK_REFKEYS_HEADER	Transfer External Billing Document	FMCA_INV	IS-PS-CA	IS-PS-CA
2	Class	CL_FMCAINV_BAPIBILL_REVERSE Method: CHECK_INPUT	Reverse billing document	FMCA_INV	IS-PS-CA	IS-PS-CA
3	Class	CL_INV_BAPIBILL Method: CHECK_REFKEYS_HEADER	Class for Billing document create	FSCR_INV	FI-CAX	FI-CAX
4	Class	CL_INV_BAPIBILL_REVERSE Method: CHECK_INPUT	Class for Billing document reversal	FSCR_INV	FI-CAX	FI-CAX
5	Class	CL_ISTINV_BAPIBILL Method: CHECK_REFKEYS_HEADER	Copy External Billing Document	IS_T_INV	IS-T	IS-UT
6	Class	CL_ISTINV_BAPIBILL_REVERSE Method: CHECK_INPUT	Reverse Billing Document	IS_T_INV	IS-T	IS-UT