Defines a method for determining the fire resistance of door and shutter assemblies and openable windows designed for installation within openings incorporated in vertical separating elements, such as: a) hinged and pivoted doors; b) horizontally sliding and vertically sliding doors including articulated sliding doors and sectional doors; c) folding doors, sliding folding doors/shutters; d) tilting doors; e) rolling shutter doors; f) openable windows; g) operable fabric curtains.