 Since older versions of DOS were not designed to cope with more than 65535 sectors, it was necessary to introduce a new partition type for this format in order to hide it from pre-3.31 issues of DOS.The original form of FAT16 (with less than 65536 sectors) had a partition type 0x04.To deal with disks larger than this, type 0x06 was introduced to indicate 65536 or more sectors.