{HEAD ~ Each transformer} 28, in association with the link 18, thus serves to transmit signals between the surface installation 16 and {TAIL ~ the tool} in question 
{ HEAD ~ Each transformer } 28 , in association with the link 18 , thus serves to transmit signals between the surface installation 16 and { TAIL ~ the tool } in question
HEAD HEAD HEAD HEAD HEAD HEAD 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