the tongue 68 is spaced a predetermined dimension from the interior surface of the bight portion 56 the space defines a gap 34 g 34 having a predetermined dimension substantially equal to but slightly greater than the thickness of the upstanding edge flange 18 the tongue gap 34 g 34 is thus adapted to receive in a locked fashion the panel aperture upstanding edge flange 18 in a manner to be described with reference to fig1 13 it will be seen that the clip fastener platform means 62 is in the form of an inverted trough shaped portion defining a central raised platform 72 formed with mirror image depending or downwardly tapered sides 74 each terminating in a foot flange 75 the platform 62 and feet 75 are in parallel relation whereby the foot flanges 75 are resiliently biased in flatwise contact with the opposed interior surface of the lower leg 54 the platform 72 has a central polygonal shaped aperture 76 through which projects an upwardly extending threaded stem 78 of a clip fastener stud the clip fastener stud generally indicated at 80 also comprises a head 82 positioned on the underside of the clip raised platform 72 the stud has a polygonal sided collar 84 at the base of its stem 78 fixedly secured in the aperture 76 as by staking portions indicated at 83 in fig1 as seen in fig1 the stud head 82 is positioned in a 34 countersunk 34 manner on the underside of the raised platform 72 the stud polygonal sided collar portion 84 conforms to the aperture 76 retaining.