The document 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 stringers 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 document may also be fitted to marine structures other than ships to serve equivalent purposes.