Abstract: An elongated hanging rail assembly (10) of the type including a rail (12) having spaced front and rear downwardly converging substantially rigid walls (15,16) defining a longitudinal recess (14) with an open mouth (18) at the bottom, and a plurality of wedging pieces (25) arranged in a longitudinal series and disposed in said recess between said walls so as to grip sheet material (11) inserted into the mouth (18) of the recess, characterized in that the wedging pieces (25) are interconnected loosely in series as a wedging assembly (13) by means of longitudinal restraining means (26) adapted to confine the wedging assembly to a predetermined maximum overall length, while the wedging piece ends which face one another, of any two adjacent wedging pieces (25) in the series, are permitted relative movement in the releasing or disengaging direction whereby a wedging piece may be disengaged when so desired without causing other wedging pieces to be disengaged.