Patent ID: 8863902

Claim:
A system of a ladder having slots in rails, usable for attaching accessories by inserting accessory attachment structures into the slots, and an accessory for attaching to the ladder, comprising: a. a ladder accessory having at least one pair of accessory attachment structures that may be inserted into at least one pair slots; b. a ladder comprising two rails connected by rungs, each rail comprising a web that is part of a beam with two parallel flanges, one flange on each side of the web, the web defining a longitudinal centerline, with a plurality of rungs attached along the centerline of the web, c. a plurality of pairs slots in the web of each rail, each slot disposed on the centerline and no closer than ⅛ inch to a rung attachment, each pair of slots in each rail being within a single between-adjacent rungs section of the web and the slots in each pair being no closer than ½ inch apart, each slot being at least 1/10 inch wide across the width of the web and at least ½ inch long along the length of the web, d. each rail including a catchment surface proximate each pair of slots, the catchment surface effective to retain at least one accessory attachment structure of the pair of accessory attachment structures when they are inserted into the at least one pair of slots, and e. each rail having affixed to an inside face of the rail, alongside the slots, a pair of guide surfaces, one guide surface on each of two sides of each slot, that restrain movement of inserted accessory structures and thereby facilitate attachment or removal of the accessory attachment structures, wherein each rail includes a metal plate affixed to the web, the plate having at least one slot aligned directly over at least one slot in the web, wherein said catchment surface and said guide surfaces being part of the metal plate; wherein each accessory structure comprises of a pin having a knob; and each slot is formed so that, after insertion into a slot each pin slides along a length of the slot until the knob slides over a portion of the catchment surface adjoining the slot, and a catch is disposed to retain each pin with its knob over the portion of the catchment surface, wherein the catch comprises a hinged spring biased latch hinged to the metal plate and having a round hole that, when engaged, surrounds and retains the knob.