{HEAD ~ Each STS3 C link} carries {TAIL ~ 640 DS0 channels} per 125 microsecond frame 
carries
{ HEAD ~ Each STS3 C link } carries { TAIL ~ 640 DS0 channels } per 125 microsecond frame
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH