This is different from bitsetting, where preset info on a blank disc's lead-in which says what type the disc is (DVD???R, RW) can be set to make it DVD-ROM. This is for older players and readers, which may well be able to physically read correctly-recorded DVD???R, RW, but can not recognize those book types, so we set it to DVD-ROM. This is mainly for DVD+R, which is not an official DVD standard.