Custom attributes are properties that you create to apply to a Site (device) and its streams. You create custom attributes when the standard properties of the Site, such as Organization, AKID, ICCID, and FW version do not meet your business needs.
The use case for custom attribute might be to give a descriptive text for a device's location rather than GPS coordinates. For example, you might want a custom attribute called Address that gives the Site’s geographic location.
Each custom attribute has a name and a value. You can assign multiple custom attributes to a Site and its devices.
When a device (a Site) is moved from one Account to another Account, all custom attributes on the Site are lost. Custom attributes must be re-added in the target Account where needed.
Therefore, before moving a Site, be sure to write down what custom attributes need to be re-added.