34 Pa. Code § 21.1
The following words and terms, when used in this chapter, have the following meanings, unless the context clearly indicates otherwise:
"A" ladder or trestle ladder-Ladder that consists of two single ladders hinged at the top to form equal angles with the base.
Extension ladder-A ladder that consists of two or more sections traveling in guides or brackets so arranged that it may be adjusted to variable lengths.
Extension trestle ladder-A ladder that consists of an "A" or trestle ladder with an additional single ladder which is adjusted vertically and provided with a device to lock it into place.
Fire ladder-A ladder used exclusively for fire purposes, but it does not include equipment of organized fire departments.
Fixed ladder-A ladder which is substantially fastened to a structure in a permanent position.
Full working length-The length of the ladder extended in extension or sectional ladders and not the sum of the lengths of the individual sections.
Ladder-An appliance designed for use in ascending or descending at an angle with the horizontal, exceeding 50° usually consisting of two side pieces called side rails, joined at short intervals by cross pieces called steps.
Portable ladder-A ladder that may be used at various locations. This term includes single, extension, step, and trestle ladders.
Sectional ladder-A ladder consisting of two or more sections which when combined will function as a single ladder.
Side-rolling ladder-A ladder running or a guide rail, generally fastened to shelving, the plane of the ladder being also its line of motion.
Single or straight ladder-A ladder consisting of only one section.
Stepladder-A ladder which consists of self-supporting flat steps or treads.
Trolley ladder-A ladder running on or in a track, fastened overhead; the plane of the ladder being at right angles to the line of motion.
34 Pa. Code § 21.1