I have a Pioneer 535 (not very old, not very new - about 2-3 years old).
It has options to manually select my TV format:

* 4:3 letterbox
* 4:3 Pan&Scan
* 16:9

I found that most movies come with 16:9 format and AUTOMATIC LETTERBOX flag on. (IFOEDIT will show this information when .IFO is selected).

With 4:3 Pan&Scan selected on Pioneer and with that flag ON in IFO file, my Pioneer will send the movie to my TV in 16:9 with black bars (top and bottom, of course). Well I was expecting to see my screen full with left and right of original picture cutted off...

If I uncheck that flag (the format stills 16:9) my Pioneer works very well, sending a 4:3 Pan&Scan picture and, if I select 16:9 TV, it will send a 16:9 picture (my PHILIPS TV automatically "converts" the image to 16:9 putting the tradicional black bars).

Now my question:
Since I'm now backing up my movies with that flag OFF (to see true 4:3 Pan&Scan) my question is:
Is that a "problem" with Pioneer or I'm not understing the true mean of those flags?

Right now I'm thinking: perhaps that flag, Automatic Letterbox, is forcing the DVD output format, overriding default settings...