When creating a union, the Access list tab lets you determine which users are allowed access to the union. The default setting is to Allow everyone access. However, if you would like specify access you can do so by selecting the Specify access option and clicking on the Add button at the bottom of the screen. This will bring up a window that lets you search for users and/or groups and give them access. You can type in the complete or part of the user name or group name and click on Search to locate the entry you're looking for.
The type of authentication, whether local Active Directory-based, is determined by the choice you've made on the Server Settings tab in the Operations Center. Please refer to the Operations Center documentation to learn more.
Note that restricting access to a union in Index Manager does not eliminate the possibility that a FotoStation configuration can in fact contain a shortcut to the archive. If a user without access tries to connect to the union, he will simply get a message stating that access to the archive is denied.
Understanding access rights on union and member index level
The access list on the Union tab controls which users can access the indexes attached to it. However, since it is also possible to specify access lists on each attached index, this requires some explaining:
When you configure a union's connection to its member indexes, you will be asked to authenticate for access to the member index. The account you specify will be stored in the union server's Operations Center, on the Authentication tab under Server Settings.
Hence, to successfully connect to a union whose member indexes have a set access list, you need to make sure that the account that is used to authenticate is also given access to the member indexes. Having done that, you can give individual users or groups access to the union on the union's access list.
When a union server connects to local indexes, i.e. indexes that reside on the same Index Manager that runs the union, the server's Process Account will be used for access to the indexes. Thus, an access list on the member indexes will have to include the process account for correct authentication.