30 39 which functions identically to slot 30 in the embodiment of fig3 outward of slot 30 39 is defined a wider opening 78 which communicates with slot 30 39 and outward of opening 78 is a plate portion 80 which closes opening 78 and affords an area for the formation of one or more openings 82 opening 78 has a vertical dimension sufficiently large to afford entry of the clip tabs between the margins that define slot 30 39 and the rear surface of the panel when the plate portion of base member 20 39 is installed against the rear surface of a panel the attachment of the base member onto the panel can be made more secure by inserting one point of a staple in the panel through hole 82 the cross member of the staple straddling the part of plate portion 80 surrounding hole 82 a first alternate of the present invention is shown in fig7 and 8 in conjunction with a pair of panels p 7 and p 8 identical to panels p 1 p 6 such embodiment employs a base member 20 installed on the edges of the wall panels in the manner described hereinabove a clip 84 is formed of resilient sheet steel or the like and has oppositely extending tabs 86 and.