If we allow the page to filter the set of presentation screens based on capabilities, then more bits of more information would be revealed. This feature, if implemented, should take privacy into consideration.

It is an open issue whether to provide filter information as part of the request for notification of available screens. This could be useful when a particular application or capability is needed in order to display the contents of a presentation. One possible approach to this could be to provide the URL for the presentation and / or required options as part of the request for notification of available screens. If this was supported, only screens that satisfied the filter would trigger a notification.