# Uniqueness of names

The item name in the system must be unique in a certain range. This chapter defines these ranges depending on the item.

If the name must be unique in the whole B3 system, then it is described as domain range.

If a given category of items contains removed items, then the uniqueness is checked only for active items.

<table><thead><tr><th width="182">Item</th><th width="146">Field</th><th width="175">Scope</th><th>Must be unique in:</th></tr></thead><tbody><tr><td>User</td><td>Username</td><td>Active users</td><td>Domain</td></tr><tr><td>User</td><td>E-mail</td><td>Active users</td><td>Domain</td></tr><tr><td>Device user</td><td>Username</td><td>Active device users</td><td>Domain</td></tr><tr><td>Object</td><td>Name</td><td>Active objects</td><td>Object groups</td></tr><tr><td>Gateway</td><td>Name</td><td>Active gateways</td><td>System group</td></tr><tr><td>Gateway</td><td>MAC address</td><td>Active gateways</td><td>Domain</td></tr><tr><td>Measuring point</td><td>Name</td><td>Active measuring points</td><td>Gateway</td></tr><tr><td>Measuring point</td><td>Local ID</td><td>Active measuring points</td><td>Gateway. The Local ID may be the same if Index or Type are different.</td></tr><tr><td>Measuring range</td><td>Name</td><td>Measuring ranges</td><td>Division</td></tr><tr><td>Alarm limit</td><td>Name</td><td>Alarm limits</td><td>System group</td></tr><tr><td>Alarm group</td><td>Name</td><td>Alarm groups</td><td>Group</td></tr><tr><td>System group</td><td>Name</td><td>System groups</td><td>Domain</td></tr><tr><td>Division</td><td>Name</td><td>Divisions</td><td>System group</td></tr><tr><td>Group</td><td>Name</td><td>Active groups</td><td>Division or parent group</td></tr><tr><td>Control point</td><td>Title</td><td>Active control points</td><td>Object</td></tr></tbody></table>