Equipment covered by this Recommendation This Recommendation is applicable to mains-powered@ battery-powered or remotely-powered telecommunication network infrastructure equipment. This Recommendation specifies requirements intended to reduce risks of fire@ electric shock@ mechanical hazards or injury for the designated classes of user@ ordinary person@ instructed person@ service person and skilled person. This Recommendation is intended to reduce such risks with respect to installed equipment@ whether it consists of a system of interconnected units or independent units@ subject to installing@ operating and maintaining the equipment in the manner prescribed by the manufacturer. Equipment complying with the relevant requirements in this Recommendation is considered suitable for use in a telecommunication network. However@ this Recommendation does not include requirements for performance or functional characteristics of equipment. Additional requirements Requirements additional to those specified in this Recommendation may be necessary for: ?C equipment intended for operation in special environments@ for example: extremes of temperature; excessive dust@ moisture or vibration; flammable gases; and corrosive or explosive atmospheres; ?C equipment intended to be used in vehicles@ on board ships or aircraft@ in tropical countries@ or at altitudes greater than 2000 m; ?C equipment intended for use where ingress of water is possible. NOTE ?C Attention is drawn to the fact that authorities of some countries impose additional requirements.