From ATSC standard (which is enacted in CFR by reference): STT - System Time Table CVCT - Cable Virtual Channel Table TVCT - Terrestrial Virtual Channel Table MGT - Master Guide Table The rules governing the transport of PSIP tables for cable are: Requirement 6: The required tables for a cable system are: the STT,either the CVCT or the TVCT, and the MGT. For any region that makes use of the capability to change the RRT, that RRT shall be included in the TS if any content_advisory_descriptor in use refers to that region. An RRT defining the rating system for a given region shall be included in the TS if any content_advisory_descriptor in use refers to that region, unless that region has explicit standards that define the rating system and the meaning of the values in the content_advisory_descriptor. Requirement 7: The PSIP tables shall describe all of the digital channels multiplexed in the Transport Stream. For convenience, the tables may optionally include information about analog channels as well as other digital channels available in different Transport Streams. Comment: Its hard to decipher, but I think it also requires RRT (Rating region Table) for US & possessions. ATSC also used outside US. From ATSC: IN CVCT: virtual channel A virtual channel is the designation, usually a number, that is recognized by the user ... Comment: I'm hard pressed to believe that cable companies expect me to remember that 116-1 is WSLS HD. That is not what their channel lineup says. However, I'm going down to the local cable company to ask them what channel is what? I haven't noticed that cable folk are required to populate tables, but I guess I'm naive - I think its implied.