Recommendation ITU-T G.664 provides guidelines and requirements for techniques to enable optically safe working conditions (for the human eye and skin) on optical interfaces of the optical transport network, in particular, for systems employing high-power Raman amplification techniques, for equipment in restricted and controlled locations. Due to revisions of relevant IEC requirements, the automatic laser shut-down (ALS) procedure, defined in a previous version of this Recommendation for synchronous digital hierarchy (SDH) systems, is no longer necessary and has therefore been moved to an informative appendix. Furthermore, this Recommendation provides new guidelines on automatic power reduction (APR) procedures for systems employing high-power Raman amplification techniques, including (in the latest version) Raman based GPON reach extension systems.