Form libraries are independent of the platform on which the forms in them are used. This means that a single form definition in a form library can include versions of the form for multiple platforms such as Windows for Workgroups, Windows NT, and Macintosh. However, if a form does not support the platform that a user is using, the default form manager will attempt to find a form server for a superclass of the message being opened to view the form instead, provided that any are available which do support the user's platform.