For the detection unit: it must respond only to the degree of freedom that carries the quantum signal and not behave differently for timing, spatial or other modes; detection probability is usually assumed independent of measurement settings and equal for all signals within a setting, so unequal single-photon detector efficiencies must be counteracted by the set-up or accounted for in the proof; and internal settings and components (detectors, modulators) must not be readable or modifiable from outside, with monitored optical isolators required as a minimum.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.