This Venn diagram looks nice, but is ultimately flawed as this form of diagram cannot accurately portray this complex system of overlapping sets. The sizes of each circle to accurately show the number of extensions known to each source, and the overlaps that are shown are approximately correct. The problem is that many more overlaps (such as the extensions in common between FFW and FDD) are not being shown at all. Sadly, a plain old list is much more effective.