Recommendation ITU-T G.9904 contains the physical layer (PHY) and data link layer (DLL) specification for PRIME narrowband orthogonal frequency division multiplexing (OFDM) power line communication transceivers for communications via alternating current and direct current electric power lines over frequencies in the CENELEC A band.

This Recommendation uses material from Recommendations ITU-T G.9955, ITU-T G.9956 and  ITU‑T G.9956 Amendment 1; specifically using material from Annex B of ITU‑T G.9955, Annex B of ITU‑T G.9956 and ITU‑T G.9956 Amendment 1. New technical material has not been introduced in this version.

The control parameters that determine spectral content, power spectral density (PSD) mask requirements and the set of tools to support the reduction of the transmit PSD can be found in Recommendation ITU-T G.9901.