The Floating Point Control (FPC) Register is non-volatile across calls with the exception of two fields: the IEEE exception flags and the DXC, which are volatile. That is, if a called routine changes any fields in the FPC register other than the IEEE exception flags and the DXC, it must save the caller's values before making the change and restore them before returning to the caller. The called routine may change the IEEE exception flags and DXC, explicitly or by triggering exception conditions, without saving and restoring the caller's values.