  This note proposes a paradigm and coordinate system that extends flat,
four-dimensional Minkowski spacetime to a broader framework that identifies an
event not only in space and in time, but also in terms of possible world, with
a third category of coordinates called ``hap'' modelling contingency and
counterfactuals. Semantically, hap is based on a Bohmian-like configuration
space, in which initial conditions at a specific moment in time uniquely
identify a trajectory. This framework can be used to support reasonings that
rigorously distinguish between causal dependencies (through time), statistical
dependencies (through space) and counterfactual dependencies (through hap). As
an example, we use this framework to show that the assumption of free choice is
not absolute, but rather depends on the chosen frame of reference: while Alice
may see a choice made freely, which is formally a unilateral, single-coordinate
translation in hap, Bob sitting in another reference frame might see this same
choice not made freely and observe instead a translation in hap jointly across
multiple coordinates, which indicates a counterfactual dependency. The
framework is agnostic regarding which flavour of the De-Broglie-Bohm theory is
considered, as it only makes general assumptions on the set of trajectories
that are commonly accepted in the Bohmian mechanics community. It is also
general enough to support reasoning on theories for which the separation
between possible worlds might also depend on the frame of reference, i.e., two
observers might disagree on whether two spacetimehap events happen in the same
world or not.
