Primary assets are the assets that should be imported first to import certain other kind of assets. Primary assets act as the default scope to import the other asset types. The assets that are imported after the primary assets are the secondary assets. Primary assets constitute the super-set of the secondary assets.
For example, in the Control Compliance Suite, you must import the Windows Domain before you import the Windows Machines. In this example, Windows Domain is the primary asset and the Windows Machine is the secondary asset. In the asset system Windows Domain is the default scope for the Windows Machines.
In the asset system, Site is the primary asset for all the asset types. When you import the assets of any asset type, you can use the Site as the scope. But, it is not recommended to use the Site as a scope even if it is a supported scope for all the asset types. You are recommended to use the default scopes.
Table: Predefined asset types and primary assets