Is it possible to use the fdisk program included with MS-DOS 6.2 to set a slave drive's primary partition to be the "Active" partition?

Suppose two drives were on the primary IDE channel, and someone needed to boot a different version of DOS from a slave drive.

When you select the slave as the fifth option in FDISK, can you set a primary partition with an OS "Active" that resides on the slave disk? Then, boot from the slave?

Why do I keep reading that you must boot from the master drive or that only the Master drive is used for booting the computer?

If you can boot from a Slave drive by setting a primary partition on it to be the "Active" partition with FDISK, what drive letter does the slave get? What drive letter would refer to the Master drive if you booted up using the slave?