Patent ID: 7938163

Claim:
A longitudinally extending frame member comprising an exterior side, an interior side, a first lengthwise end section, a lengthwise shoulder section adjacent to said first lengthwise end section, and a second lengthwise end section that is opposite to said first lengthwise end section, said first lengthwise end section having a generally planar surface that is generally orthogonal to said exterior side, said lengthwise shoulder section having a generally planar shoulder surface that is substantially parallel to the generally planar surface of said first lengthwise end section, said longitudinally extending frame member further including a first longitudinally extending channel in said exterior side for receiving spline material, said first longitudinally extending channel having a predetermined channel depth that extends in a first direction and a substantially “U” shape, said first lengthwise end section further comprising a rear side that is opposite said exterior side and a second longitudinally extending channel in said rear side, said second longitudinally extending channel having a channel depth that extends in a second direction that is opposite said first direction, said longitudinally extending frame member further comprising a third longitudinally extending channel that is located between said longitudinally extending shoulder section and said first lengthwise end section and which is adjacent to said second longitudinally extending channel, said third longitudinally extending channel having a channel depth that extends in a third direction that is generally orthogonal to said first and second directions, said longitudinally extending frame member further comprising a fourth longitudinally extending channel in said second lengthwise end section, said fourth longitudinally extending channel having channel sidewalls that are angled outward and away from each other and a channel depth that extends in a fourth direction that is opposite said third direction and substantially orthogonal to said first and second directions, said second lengthwise end section further comprising generally planar surfaces that are located on either side of said fourth longitudinally extending channel and which are substantially parallel with said generally planar shoulder surface and said generally planar surface of said first lengthwise end section.