By default, phpBB redirects the user to the main forum page upon logout. This is perfectly fine for someone who uses phpBB solely as a forum. However, in other instances it may be good to redirect the user to the previous page they logged out from. This could be a topic, or forum view, but more commonly this could be the main page of the website or any other page they were previously logged in at.
I would propose allowing for the &redirect variable to be available during the logout call and to allow redirection after logging out.