Figure 9 Overlapping regions in XSL-FO 1.0 denoted in dashed areas. Figure 8: Two different shapes composed by a different number of primitives. On the other hand, an unlimited number of possibly over- lapping page regions entails that an unlimited number of re- gion overlapping combinations may take place. Moreover, the possibly non-rectangular shape of the overlapping areas implies that when such an overlapping occurs, the clipping of areas must be performed through constructive area ge- ometry instead of simply adjusting the dimensions of a rect- angle, as is currently done in XSL-FO. We therefore propose two additional attributes for the arbitrary region element, which should enable the proper specification of overlapping behavior for non-rectangular areas. These attributes are described in Sections B.3.4] and [3.3.5]