IEC 61935-1 is an international technical specification that defines procedures for testing installed metallic data cabling. In practice, this means that this standard serves as a "manual" for certification measuring instruments, known as cable testers. It specifies which particular electrical properties of the cable are to be measured, in which frequency ranges and with what required accuracy. This ensures that the measurement results are consistent and comparable, regardless of which certified tester from which manufacturer is used for the measurement. Some of the parameters tested include signal attenuation, which is the weakening of a signal as it passes through a cable, and crosstalk, which is unwanted interference between pairs of conductors in a cable. The output of such measurements is then a report that clearly confirms whether or not the cabling under test complies with the limits, which is key to ensuring reliable data transmission in computer networks.