Looking for tech details about DVD Regions



Many people seem to be happy being able to use patched firmwares, or other programs to get around region codes. However for some of us, there is a need to understand what is going on.

In the case of patched firmwares, I can understand essentially what is happening, however when it comes to software such as DVDRegionFree which claims to unlock region protected discs, I am still perplexed.

As I understand it DVD Regions can be enforced in multiple places, on the drive itself, and in software used for playback. I can see where software would help in the case of acting as a device driver, proxying requests from the playback software and lying to it, but how can software (even at a driver level) evade protections implemented on the hardware itself ?