{HEAD ~ A traverse mechanism} may be provided to allow {TAIL ~ the coring bit} to be advanced into a pipe being cored 
provided to allow
{ HEAD ~ A traverse mechanism } may be provided to allow { TAIL ~ the coring bit } to be advanced into a pipe being cored
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH