Read and understand this about Real Digital Tv Channels and Virtual Digital Tv Channels ,
http://forum.tvfool.com/showthread.php?t=695 . When the the Tv or Converter scans for digital channels it finds the Real Channel and displays the Virtual Channel. The Real Channel and the Virtual Channel can be the same or not the same. Some times channel numbers are not listed because of a lack of information. However the Virtual Channel is not really a channel. You can read about PSIP if you like. PSIP can receive a real channel number and display a different channel number.
http://en.wikipedia.org/wiki/PSIP .