Anamorphic DVD vs "enhanced4widescreen??

I would like to understand what the DVD is doing when it says on the DVD that it is Anamorphic, and/or "enhanced for widescreen viewing". I KNOW it allows the owner of a widescreen TV or of a 3:4 with 16:9 squeezeability to use all the scan lines... I just want to understand HOW the DVD player "sees" this and why a normal letterbox DVD without this special thingy can't be used this way????
I want the really technical stuff!!! anybody know and willing to explain in 1,000 words or less? (or even steer me to a book...)
Check out the book "DVD Demystified", It's available on Amazon.
Thanks, my library has a copy!!
Elizabeth, try this link. Hope this is what your looking for :)
Interesting link... Thanks
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