This technical information report (TIR) provides the details of how to correctly build, calibrate, and use the CMR test circuit specified in ECG performance standards. It also preserves the history, rationale, and performance requirements of the test method, as included in ANSI/AAMI EC13:2002, Cardiac monitors, heart rate meters, and alarms, which was revised by the adoption and finalization of ANSI/AAMI/IEC 60601-2-27:2011, Medical electrical equipment - Part 2-27: Particular requirements for the basic safety and essential performance of electrocardiographic monitoring equipment.