A second coding device is located in the write path and removes runs of zeros in {HEAD ~ interleaved subsequences} in {TAIL ~ the scrambled user data} 
A second coding device is located in the write path and removes runs of zeros in { HEAD ~ interleaved subsequences } in { TAIL ~ the scrambled user data }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL