Alternatively, the shuttle element may simply be {HEAD ~ a separating element} that does not form {TAIL ~ a tight seal} in the paint line, but only forms an unsealed boundary between the paint and the auxiliary medium 
Alternatively , the shuttle element may simply be { HEAD ~ a separating element } that does not form { TAIL ~ a tight seal } in the paint line , but only forms an unsealed boundary between the paint and the auxiliary medium
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH