somewhat: This explains it a bit http://en.wikipedia.org/wiki/DOCSIS- even mentions TCL's system, or http://en.wikipedia.org/wiki/Hybrid_Fibre_Coaxial
The correct Wiki link is http://en.wikipedia.org/wiki/Hybrid_fibre-coaxial (note the "_" and the "-". Sigh.) That gives the best description of what a head-end is.