This part of IEC 61237 describes methods of measurement and special test signals for the analogue audio part of equipment mainly dedicated to recording reproduction of TV signals on magnetic tape on reels or in cassettes. The allowable tolerances for the rated values for acceptable performance are not given in this standard, but may be derived from the specifications for the related system i.e. appropriate publications, manufacturers' specifications, etc. The necessary reference and calibration tapes are either mentioned in the specific IEC publication of the equipment under test or included in IEC 61105 and IEC 61295, respectively. The methods are applicable to acceptance tests, performance comparison and, as far as possible, to routine checks. To ensure that the results obtained at a specific time and at a specific place are comparable to other measurements, it is advisable to specify the test signal, measuring devices and types of tapes used together with results obtained.