b the length of the spacing regions 70 e is determined such that the vertical support members 34 and 36 fit snugly between the vertical portions 72 and the outer ends 70 c in the case of the proximal bracket assemblies 54 and 56 the length of the spacing regions 70 e allows the vertical support members 34 and 36 to fit snugly between the vertical portions 72 of the third and fourth bracket members 60 and 64 and the first and second hinge assemblies 62 and 66 respectively when as is typical two by four dimensional lumber is used to form the vertical support members the length of the spacing regions 70 e will be approximately 3 1 2 u2033 or slightly greater to allow for variations in the true dimensions of the lumber the vertical portions 72 each comprise the outer ends 72 a discussed above and an inner end 72 c the bracing regions 72 b are located approximately 85 of the distance between the horizontal portion ends 72 a and 72 c as measured from the outer ends 72 a the vertical portions 72 thus each define a main region 72 d between the outer end 72 a and the bracing region 72 b and an inner end region 72 e between the bracing region 72 b and the inner end 72 c in the horizontal portions 70 of the exemplary brace members 50 52 60 and 64 first second and third fastener holes 90 a 90 b.