To save having to type full device paths, aliases can be used. For the most common devices these are already defined, e.g.cdrom. The command devalias is used to define aliases.
Aliases defined by devalias are temporary and are lost after a power cycle or system reset.
Device trees can be shown with Unix like commands e.g. ls, pwd, cd . It also enables restricted monitor format, i.e. a menu. This is a portion of nvram reserved for user commands.