{TAIL ~ DS3 AIS/Idle code generation} means generates DS3 AIS/Idle code bytes in {HEAD ~ response} to the local STS 1 clock signal 
{ TAIL ~ DS3 AIS / Idle code generation } means generates DS3 AIS / Idle code bytes in { HEAD ~ response } to the local STS 1 clock signal
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH