I guess you don't know as much as you think you do.
I got a couple of these, back when the government was subsidizing DTV converters a while ago. They're sitting down in the basement.
Many of these DTV converters offered some kind of an on-screen program guide grid, as a feature. What made the DTVpal Plus unique, was that the program guide it created, was made available as TVGOS data. Check out the chapter in its User Guide entitled "TV Guide On Screen or Guide Plus Setup". There is also a table of "fake" zip codes, such as Denver CO is 00020, and Wilkes Barre PA is 00051.
Like I said, I never really played around with it. First, until a few days ago, I didn't have any need to create my own TVGOS. Second, I really don't have local over-the-air stations, and such is required since the DTVpal Plus converter only works with ATSC signals, not QAM signals.