The windowing of attention in language

An extruded, generally J-shaped plastic welt or trim strip adapted to be sewn to a seat cover has an inverted lip portion at the tip of its short leg. The welt strip is adapted to cover both sides of a vertical, downwardly extending peripheral flange on a metal seat pan. The welt strip is retained against removal from the seat pan by the engagement of its inverted lip portion with a plurality of upwardly and inwardly directed tabs which are struck out of the material of the flange.