  Although it was Aczel’s [1988] book that made the idea of Accessible Pointed Graph common currency, the idea goes back at least to Hinnion’s Ph.D. thesis [1974] and in a less developed form to Specker’s (unpublished) Habilitationsschrift and quite possibly earlier. Aczel used this technique to provide models of Forti-Honsell’s antifoundation axiom [1983]; Hinnion’s idea was to use isomorphism classes of wellfounded pointed extensional relational types to interpret theories of wellfounded sets in NF. With wellfounded extensional relations one does not need to make the pointing explicit, since the wellfoundedness ensures that at most one element of the carrier set can satisfy the accessibility condition. (This is not so in general: the two sets \(x = \{y\}\); \(y = \{x, \varnothing \}\) have set pictures that have the same binary relation but different pointing.) In NFU each set picture is a set (a big set, as it happens) and Holmes showed that in a model arising à la Boffa the set pictures reproduce the sets of the original nonstandard model. This striking phenomenon – which has no parallel in the study of NF – justifies Holmes’ dictum that “NFU can be understood as the theory of certain nonstandard models of Zermelo-style set theory with automorphisms.”