| Code Value |
Definition |
| Ack | Acknowledgment of receipt of an earlier message |
| Cancel | A cancellation or revocation of a previous message |
| Dispatch | A commitment of resources or assistance |
| Error | Rejection of an earlier message (for technical reasons) |
| Report | New information regarding an incident or activity |
| Request | A request for resources, information or action |
| Response | A response to a previous request |
| Sensor Configuration | These messages are for reporting configuration during power up or after Installation or Maintenance |
| Sensor Control | These are messages used to control sensors/sensor concentrator components behavior |
| Sensor Detection | These are high priority messages which report sensor detections |
| Sensor Status | These are concise messages which report sensors/sensor concentrator component status or state of health |
| Update | Updated information superseding a previous message |