What's that P/S - LB button do on my DVD player?

[digiboy]

OK don't worry, I know what Pan & Scan is, and I know what letterbox is. I have well over 500 DVD's that are a mix of both, Letterbox wherever available.
Here's the deal:
I have a regular Sony 27" set, good quality with stereo and S-Video options.
I have an inexpensive Apex DVD player, the only one I've ever owned. IT's been a great little workhorse.
It has a setup menu that you access from the remote.
In the setup menu there is an item called "TV display" and it has 3 options:
Normal P/S
Normal LB
Wide
Now if I set the option to "wide" , all images from the player come out distorted so I assume that is for newer 9x16 sets....not usable for me.

BUT: Setting the player either to Normal P/S or Normal LB has never made any difference at all in the way DVD's display on my set. Letterboxed DVD's appear letterboxed, full screen types like for older films display full screen. Switching between those 2 settings on the player makes no difference that I can see. All DVD's always display correctly....until now.

I just bought a DVD of an old Sci-Fi film, "Target Earth" which claims to be widescreen 1.85. But it shows up full screen when I play it. Then I notice some of the credits are getting cut off. So on a whim I go into that DVD menu and seeing it happens to be set on "normal P/S" I flip it over to "normal LB"
Eureka!
The movie displays correctly at 1.85!

Now why does that menu setting on the player make a difference on this DVD while all my other DVD's display correctly regardless?

Are there other DVD's like this? What's making the difference?

[chipmac]

The Normal P/S mode is what your player refers to as the Zoom mode. It basicly zooms into the center of the image on widescreen DVDs for a suedo P/S look but it only works on DVDs that are flagged to use this function of the player and many DVDs don't have this flag set which is why you've never seen it in action before.

[digiboy]

Hi Chip,
Well that makes perfect sense but it must be a very rarely used function. I also rent and borrow DVD's in addition to playing my own. I've probably had that option set to "Normal P/S" for at least a year. I'm sure I would have noticed any other DVD not playing in a widescreen AR if it was supposed to. This has got to be the first time that the feature has kicked in on my player.