Figure 24. The combined family structure of entailments for most of the metrical relations discussed. The figure shows that there are two separate sets of meter relations: between B-related and U-related meters respectively. Double-line arrows stand for entailments (such as V → B or O → U), single solid lines indicate the possible coexistence of relations which do not entail each other (such as V – C), and dashed lines serve to remind that the entailments do not go both ways (V and C both entail B, but B does not necessarily entail either V or C). To that effect, note that there are also pairs of meters for which neither B nor U hold.