The spec should specify any restrictions on the presenting browsing context when the opening browsing context is in "incognito" mode.

From public-webscreens and related threads:

The specification should define the behavior of the following Web features for the presenting page across presentation sessions. The goals are the following:

1. Ensure that the same presentation will behave correctly in the 1-UA and 2-UA cases
2. Information does not leak from presentation session to session in cases where the controlling pages may represent different authorization domains (e.g., logged-in users).

The following Web features have been discussed (and there may be others to consider):

• Cookies and local storage
• Sensor APIs (geo, orientation, etc.)
• Browser extensions
• HTTP Cache
• Shared Workers