§4 & Appendix A
Six factors, each raised to its own weight and multiplied together. This runs the same arithmetic as Appendix A's reference implementation, in your browser — nothing here is sent anywhere.
ER = clamp(floor(16 × F_tamper × F_AS1.00 × F_net0.50 × F_tx0.25 × F_content1.50 × F_name0.75 × F_time0.25 + 0.5), 1, 255), then floored again against whatever rating the packet already carried on arrival. Full derivation in Section 4.