system with DOS 3.0. Support for an extended partition, a special primary partition type used as a container to hold other partitions, was added with DOS 3.2, and nested logical drives inside an extended partition came with DOS 3.30. Since MS-DOS, PC DOS, OS/2 and Windows were never enabled to boot off them, the MBR format and boot code remained almost unchanged in functionality (except some third-party implementations) throughout the eras of DOS and OS/2 up to 1996.

In 1996, support for