in order to provide a pleasing aesthetic appearance , and also in order to enable concealed , directional lighting to be used , an openword grid - like suspended ceiling system has outer squares which contain four inner blades forming an inner square surrounded by four rectangles . light fittings are associated with the rectangles so that the axis of a light fitting can be inclined . in order to enable the ceiling system to be packaged at low packing density , the four inner blades are hinged to each other and collapse so as to lie parallel to each other . after opening out , they can be hooked into the sides of the outer squares .