 In the Ockhamist semantics, formulae are interpreted in a model on a tree \(\mathcal{T} = \langle T,\prec\rangle\) at pairs \((t,h)\) consisting of a time instant \(t\in T\) and a history \(h \in \mathcal{H}(t)\) containing that instant. Sometimes the instant-history pairs \((t,h)\) are conceived of as ‘initial branches’ that start at the instant \(t\) and span the possible future specified by the history \(h\) (see e.g. Zanardo 1996).