Difference between major and minor number in AIX

A major number refers to a type of device, and a minor number specifies a particular device of that type or sometimes the operation mode of that device type. Example:

# lsdev -Cc tape
rmt0 Available 3F-08-02 IBM 3580 Ultrium Tape Drive (FCP)
rmt1 Available 3F-08-02 IBM 3592 Tape Drive (FCP)
smc0 Available 3F-08-02 IBM 3576 Library Medium Changer (FCP)

In the list above: rmt1 is a standalone