13 finally terminates at a second end 66 of the lip portion 68 the spring clip 13 preferably has a notch indentation or tang 44 located so as to engage the support notch 38 a first tang 48 adjacent the second bend 58 and a second tang 46 generally adjacent the third bend 62 the width of the first and second tangs 48 and 46 are substantially the same as the width of the head groove 18 the width of the notch tang 44 is substantially the same as the width of the support notch 38 in operation the head 12 is positioned on the top support surface 30 between the first and second registration flanges 32 and 34 the spring clip 13 is then pressed over the outer edge 40 of the support 11 and over the head 12 with the base portion 52 pressing upwardly against the bottom support surface 36 with the first bend 50 generally conforming to the corner region between bottom support surface 36 of the support 11 and the outer edge 40 of the support 11 the notch tang 44 is located for extending into and fitting tightly in the support notch 38 the edge portion 56 of the clip 13 is positioned opposite the second side surface 24 of the head 12 with the arch portion 60 extending over and pressing down on the top head surface 16 with the lip portion 68 adjacent the first side surface 22 the first tang 48 fits.