Nintendo's Wii and Nintendo GameCube have their own specialty format for copy protection. It is based on DVD/miniDVD (Game Cube) technology; each disc contains some deliberately placed defects. The exact positions of these defects, which differ for each produced disc, is encoded encrypted in the BCA of each disc. The BCA is readable on most standard DVD-ROM Drives, but consumer burners can reproduce neither the BCA nor the defects. As an additional obfuscation mechanism, the on-disc sector format is a little bit different from normal DVDs. Nevertheless, it can be read using some consumer DVD-ROM drives with a firmware modification or "debug mode". It is also possible to hack the Wii to install unlicensed software, some of which can use the Wii's own drive to create disc images and then play these copies.