In ordinary quantum theory or string theory, the fundamental observables are correlation functions or scattering amplitude that can be measured by particle physics experiments .
In loop quantum gravity, the fundamental observables are gravitional holonomies that can be detemined by a pair of particle spins when they reunion.
In causal set theory, causal structure are taken to be fundamental as a pregeometry structure. By this, my question is what is the fundamental observables in casual set theory. What we can measure to determine the dynamical ingredients in it?