{HEAD ~ The panel} of substrate material 18 has a surface 19 and {TAIL ~ a thickness t} 
{ HEAD ~ The panel } of substrate material 18 has a surface 19 and { TAIL ~ a thickness t }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL