The contents of the post message the generated page will send if the versions don't match.
The title of the page that will be generated to respond in case the versions don't match.
The name of the query string variable the middleware will check in order to identify
whether the request comes from a popup or not. The variable must have 'true' as its
value.
The options for how to detect if the request comes from a popup and how to compose the post message the middleware will use to respond.