A Unique Zone is a Zone that has been used in at least one Project and that has different spatial characteristics from other Zones used in the Projects of the account or study.
Unique Zones are only important if the subscription (generally Project Subscriptions) has a number of Zones listed in the contract. This number is known as a Zone Quota. Each Unique Zone will count against the Zone Quota the first time it is used in a Project. Subsequent Project runs with the same Zone will not count against the Zone Quota.
Any changes to the Zone, such as moving, adding, deleting points that change the spatial characteristics, will result in a new Zone. Zones copied and re-uploaded without changing the spatial characteristics will not be considered new Zones. Zones with modified properties such as Zone name, direction, pass-through, calibration information will not be considered new Zones.