The matrices on ◘ Figs. 4.4, 4.5, 4.6, and 4.7 represent the attempt to illustrate elementary structural forms by arranging them according to a few elementary distinction criteria. As a representative of the overall structure, the covering is examined, being the most significant component for performing demanding structural task, namely supporting loads perpendicular to its axis. It is also for this reason that the different variants studied are classified according to the design of the covering. The vertical enclosure elements are involved in the analysis to the extent that they participate in the structural behaviour of the basic structural cell and therefore interact in structural terms with the covering. The analysis is differentiated according to the latter’s shape and the way in which it is supported.