This International Standard specifies the types, dimensions, material, manufacture and designation of rungs for dog-step ladders; it also lays down the installation and composition of single rungs forming a dog-step ladder. Dog-step ladders, formed from single rungs, may only be used where fixed vertical ladders with stringers1) cannot be installed. Dog-step ladders fitted to the ship's structure should serve only to bridge minor differences in height. Dog-step ladders as specified in this International Standard may also be fitted to marine structures other than ships to serve equivalent purposes. NOTE 1 Users of this International Standard should note that they should ensure compliance with such statutory requirements, rules and regulations as may be applicable to the individual ship or marine structure concerned.