When a user attempts to log in, Fluid Topics looks for that user by checking each realm in a certain order. The order is determined by the list of realms in the Realms tab of the Authentication administration interface. It is possible to modify the order of the list by using the up and down arrows or dragging and dropping a realm to a new position in the list.
Use case
When more than one OpenID Connect or SAML realm is configured, it is useful to be able to define an order of precedence in order to display one login button before the other.