| Priority | Class | Meaning |
| 0 to 15 | 0 | Total failure, results in blocking the operation enablement. |
| 16 to 31 | 1 | Total failure, results in blocking the operation enablement. |
| 32 to 47 | 2 | General failure. |
| 48 to 63 | 3 | General failure. |
Alarm Class is used to group multiple priorities into one category. This category is then used for reporting between different alarm blocks (AlarmsAggregator, AlarmsExtender, and AlarmsCoupler) using the AlarmsStatus structure.
If the priority is odd, it will automatically reset after it ceases.
For even classes, the corresponding alarm output (Alarm*Flag) remains active even in the remembered alarm state (i.e., Memory, AckedMemory). For odd classes, it is active only if the alarm itself is active (i.e., Active, ActiveAcked).