Under FPT_PHP.3, measures how much the transmitter's optical isolation attenuates light injected from the quantum channel and compares it with a threshold, so injected light cannot reach and manipulate or read internal components (Trojan-horse and laser-seeding attacks). Individual sub-assemblies may be tested where whole-module measurement is insufficient.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.