Recommendation ITU-T G.9991 specifies the system architecture, physical (PHY) layer and data link layer (DLL) for high-speed indoor optical wireless communication transceiver using visible light.

Amendment 1 includes updates on security to accept IEEE 802.1X-based authentication and alignment with ITU-T G.9960/G.9961 Recommendations.

Corrigendum 1 includes further alignment to Recommendations ITU-T G.9961/ITU-T G.9962.