The standards specified for that development are that the development must--
(a) be erected, used, altered or added to in connection with filming that is exempt development, and
(b) not be at the location for more than 30 days within a 12-month period, and
(c) if it is an alteration or addition to a building or work--not remain in place for more than 30 days within a 12-month period, and
(d) not, in its altered or added to form, be accessible to the public.