{HEAD ~ Each carriage} has {TAIL ~ a rearwardly projecting tongue}, slidably received in a slot formed in flange structure on the port plate 
has
{ HEAD ~ Each carriage } has { TAIL ~ a rearwardly projecting tongue } , slidably received in a slot formed in flange structure on the port plate
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH