{HEAD ~ Contoured stationary plows} are included at {TAIL ~ a downstream end} of the contiguous belt spans to assist in turning the envelopes over 
{ HEAD ~ Contoured stationary plows } are included at { TAIL ~ a downstream end } of the contiguous belt spans to assist in turning the envelopes over
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH