This report provides general guidance on the steady-state performance requirements of HVDC systems. It concerns the steady-state performance of two-terminal HVDC systems utilizing 12-pulse convertor units comprised of three-phase bridge (double way) connections, but it does not cover multi-terminal HVDC transmission systems. Both terminals are assumed to use thyristor valves as the main semiconductor valves and to have power flow capability in both directions. Diode valves are not considered in this report.