In Prior’s [4], Appendix A §4 and §5, and Chapter IV, and more explicitly in Bull’s [2], we find sequences of tense-logical systems which place increasingly more restrictive conditions on the temporal relation “… is before …”. We give here a simple, diagrammatic account of the way in which the successive postulates for temporal order place these conditions on the temporal relation: we do not provide any essentially new semantics for these systems, nor do we prove any rigorous metatheorems. We (...) do, however, quite often assume the completeness results of Lemmon, Bull and others without explicit mention. (shrink)