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