Visibility Rule Property of a Link
The Visibility Rule property of a link uses these values to determine if Siebel CRM displays the link:
Always. Allows visibility rules in the child records when the current master-detail view references this link. This situation is true even if the Visibility Applet and Visibility Applet Type properties of the view are not defined.
Never. Disables visibility rules in the child records if the current view references this link.