This document covers shielded and unshielded free and fixed connectors, circular or rectangular, for balanced single-pair data transmission, with current-carrying capacity.

It specifies the IEC 63171 series' common mechanical, electrical and transmission characteristics and environmental requirements, as well as required test specifications.

This document does not describe a specific mating interface. Detail specifications of mating interfaces complying with this document can be found in the family of detail specification standards IEC 63171‑X (type X).

Within their own type, the shielded and unshielded connectors are interoperable for their transmission performance and can be exchanged; though the shielded version has improved alien crosstalk and coupling attenuation properties.