The system 4 in which {HEAD ~ the means} for providing a test signal is {TAIL ~ a video signal storage and retrieval system} 
is
The system 4 in which { HEAD ~ the means } for providing a test signal is { TAIL ~ a video signal storage and retrieval system }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL