The loop (zone) number is required to add a guarded facility to the CMS along with descriptions of all devices connected to the hub.
The loop (zone) number is available in the settings after activating the group mode in the Ajax application (Hub → Settings ⚙️ → Groups).
Having selected a group, you will see a list of its devices. Each device has a Device No. (or DeviceIndex in PRO Desktop) that corresponds to the loop (zone) number.
A number is assigned when a device is attached to the Hub (the first added device has the first loop (zone) number).
After a device or a detector is removed, its number will be assigned to the next added device. However, the numbering of other devices will not change.