   When assessing whether a sentence receives a stable truth value, the RTT considers sequences of hypotheses of length  On.  So suppose that S is an   On-long   sequence of hypotheses, and let ζ and η range over ordinals. Clearly, in order for S to represent the revision process, we need the ζ+1st hypothesis to be generated from the ζth hypothesis by the revision rule. So we insist that Sζ+1 = τM(Sζ). But what should we do at a limit stage? That is, how should we set Sη(δ) when η is a limit ordinal? Clearly any object that is stably true [false] up to that stage should be true [false] at that stage. Thus consider Example 3.2. The sentence A2, for example, is true up to the ωth stage; so we set A2 to be true at the ωth stage. For objects that do not stabilize up to that stage, Gupta and Belnap 1993 adopt a liberal policy: when constructing a revision sequence S, if the value of the object d ∈ D has not stabilized by the time you get to the limit stage η, then you can set Sη(δ) to be whichever of t or f you like. Before we give the precise definition of a revision sequence, we continue with Example 3.3 to see an application of this idea.  