A + registerFoo() has never been called. B + registerFoo() has been called, but user was not notified. - registerFoo() has been called, user has been notified, and: C + user has not responded D + user has declined once but is open to future notifications - user has accepted and: E + the handler is a non-default handler, and there is no default F + the handler is the default handler G + some other handler is the default handler H + since unregistered the handler, but is open to readding it I + since unregistered the handler permanently (blocked site) J + user has declined permanently (blocked site) K + site has unregistered itself but user is open to seeing it again L + site unregistered itself; user made that permanent (blocked site)