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In Chapter XIII of , Prior discusses a system QKt, designed to stand to the “minimal” tense logic Kt as the modal system Q of  stands to S5. In this paper I provide semantics for a similar system, slightly weaker than QKt: the weakening is due to the fact that Prior's axioms are slightly too strong for a “minimal” system. An extended post-Henkin style completeness proof for the axiomatization with respect to the semantics provided is then given: the underlying three-valued nature of the semantics requires a twist in the proof which is new to its author at least, and also results in some details being set out which could well be glossed over in the two-valued case.