There's three regions missing here - region 0 is "worldwide", region 7 is "special purpose", Oscar screening DVDs and the like, and region 8 is "international waters" for cruise ships and things. You can set several regions on the same disk, to make a 2/4/5 and the like. Set each region as a bit, and you can store that in a single byte - that makes it very easy to flash the firmware on DVD players to decide which disks they can play. Aus/NZ will want content in English and Latin America will want Spanish or Portuguese, so the DVD consortium can still get up to their often-illegal, certainly immoral, price fixing and bullshit.

Really, fuck DVDs. So much potential in the increased capacity, and then it was mired in crap like this and "disabled user operations" so that you can't skip trailers. Time to raise the black flag and set sail for prosperous waters, me hearties.