 The semantic elements here are in large part analogous to those for SDL. We have a binary relation again, but this time instead of a relation interpreted as relating worlds acceptable to a given world, here we will have a relation, \(R\), relating worlds “accessible” to a given world (e.g., possible relative to the given world). The only novelties are two: (1) we add a simple semantic element to match our syntactic constant “\(d\)”, and (2) we add a slightly more complex analog to seriality, one that links the accessibility relation to the semantic element added in order to model \(d\).