🚀 go-pugleaf

I just got a VCR Plus device (@Fry's in LA for $28.88) and think it's the greatest thing since sliced bread.  No, I am not VCR illiterate. It's just that I have an old VCR which does not have on-screen programming. 

I am new to this newsgroup and I have been trying to figure out how the VCR Plus codes are derived? 

My inquiry is purely academic. I don't intend to invent my own device.
I've tried to determine if there is a consistent pattern, but have found none.
I suspect there is some sort of encryption. I have also noticed that prime time 
shows on channels 2-13 have codes with the fewest digits.

I was told by a helpful netter in rec.puzzles that this newsgroup has been down this line of inquiry before.

If this query has already been answerd in a FAQ, let me know where I can get it or e-mail it to me.
If this is the wrong group for this I apologize and point me in the right direction.

Thanx