 It should, however, be noted that Prior also often used tense-operators without any reference to time units. He used \(F\) for “it will be the case that …” and \(P\) for “it has been the case that …”. In terms of these non-metric tense-operators he defined the operators, \(G\) and \(H\), as \({\sim}F{\sim}\) and \({\sim}P{\sim}\) respectively. \(G\) may be read “it will always be the case that …”, and \(H\) may be read “it has always been the case that …”. Using these non-metric tense-operators Prior (1967, p. 32 ff.) even formulated a reconstruction of the Diodorean Master Argument which comes rather close to the classical argument which we shall present in the following.