36. The system of claim 34 further comprising means for transmitting from each of said local sites to said central site information concerning the occurrence of broadcast segments and means at said central site for logging said information.
36. The system of claim 34 further comprising means for transmitting from each of said local sites to said central site information concerning the occurrence of broadcast segments and means at said central site for logging said information. 37. The system of claim 36 further comprising means at said local site for storing the temporary digital signature of a potential unknown segment and for logging the occurrences of said potential unknown segment based on said stored temporary signature, and means for transmitting said log information to said central site after said central site has identified said potential unknown segment.