In accordance with another feature of the present invention, the abutting edges may also have toothed portions defined by {TAIL ~ straight lines}, for example, toothed portions formed by triangles, rectangles or {HEAD ~ trapezoids} 
In accordance with another feature of the present invention , the abutting edges may also have toothed portions defined by { TAIL ~ straight lines } , for example , toothed portions formed by triangles , rectangles or { HEAD ~ trapezoids }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD