I'm just saying that UPN 21 has apparently paid for the re-broadcast of a small amount of HDnet original programming. You can see an HDnet original program like "Across America" every now and then on the OTA broadcast of UPN 21. But at the same time, if for example you subscribe to DTV, tune to HDnet, their LIVE programming could have Hogan's Hero's or Charlie's Angels airing.
HDnet's real time broadcast here in DFW is not OTA.