Priority levels

Each job can have one of the following priority levels:
Critical
Highest priority user jobs.
High
High priority user jobs.
Normal
Normal priority user jobs.
Low
Low priority user jobs such as background loads and jobs that should not affect other activity.
Note: There are two additional priorities, but these are used exclusively by internal processes and are not visible to and cannot be set by users:
System critical
This priority is ranked higher than critical.
System background
This priority is ranked lower than low.