This Recommendation applies to surge protective devices (SPDs) to be used for Ethernet primary protection in surge voltage environments with a peak value of 2.5 kV and above. It covers the following device parameters: a) electrical surge b) electrical d.c. c) identification and marking. This Recommendation does not deal with: a) mountings for SPDs and their effect on characteristics; b) mechanical dimensions; c) quality assurance requirements; d) units containing current limiters; e) signal performance parameters@ standards such as [b-IEC 60603-7-7] may be used for this purpose; f) diagnostic properties such as indicators and status monitor outputs.