IEC 61156-9:2016(E) describes cables primarily intended for the fixed part of channels as defined in ISO/IEC 11801 and in ISO/IEC TR 11801-9901 which is planned to be included in the next edition of ISO/IEC 11801-1. It covers overall screened cables with screened (X/FTP) or unscreened (X/UTP) pairs, where X stands for F, S or SF, as well as pair-screened cables without overall screen (U/FTP). The transmission characteristics of these cables are specified up to a frequency of 2 000 MHz and at a temperature of 20 °C. Two categories of cables are recognised: - Category 8.1 for use in Class I according to ISO/IEC TR 11801-9901; - Category 8.2 for use in Class II according to ISO/IEC TR 11801-9901.