IEC 61788-7:2020 is available as IEC 61788-7:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61788-7:2020 describes measurement of the surface resistance (Rs) of superconductors at microwave frequencies by the standard two-resonator method. The object of measurement is the temperature dependence of Rs at the resonant frequency. The applicable measurement range of Rs for this method is as follows: - Frequency: 8 GHz < f < 30 GHz - Measurement resolution: 0,01 m Ω at 10 GHz The Rs data at the measured frequency, and that scaled to 10 GHz, assuming the f 2 rule for comparison, is reported. This third edition cancels and replaces the second edition, published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) informative Annex B, relative combined standard uncertainty for surface resistance measurement has been added; b) precision and accuracy statements have been converted to uncertainty; c) reproducibility in surface resistant measurement has been added.