D36 — Impedance rules computed and reported only

Superseded by D58

Decision

Impedance rules (P4) are computed and reported only: width/gap per routing layer from the board stackup in tracemaker rules; routing widths and net classes are unchanged and --component-rules stays off by default

Alternatives

Synthesise per-layer net classes and route with them

Reason

The benchmark has no stackups (0 of 1,157 PCBench unrouted files), the formulas carry ±2–8 % model error plus ±10 % fab tolerance, and the reference-plane assumption is not yet checked by plane coverage; a report lets a designer confirm before anything is enforced (doc 15 §14.5)