A spatially varying causal benchmark

A register route with this printed profile is certifiable even when a constant-speed route with the same endpoints is not. A controller may select among finitely many such routes only after its selecting record reaches the route's departure port. Preloading a known function $c(t)$ is not an instantaneous global feed-forward operation.

Taking an independently declared finite sequence of transport and local gates along these routes gives a nontrivial exact discrete target. Applying Theorem thm:physical proves its causal safety; equality of the implemented gates with the declared target proves its accuracy. No wave-equation discretization is claimed.