← All chapters Chapter 25

Appendix D — Diagnostic Coverage from the Implementation

The category is not the coverage; earn the number.

Diagnostic coverage is defined against a specific mechanism and its specific failure modes, not entitled by a class quoted from a standard's table. A range check catches an open circuit but not a plausible-but-wrong reading. Derived from the tree, coverage becomes readable: a covered mode moves off the order-1 list, an uncovered one stays a single point, and detection after the FTTI is no coverage at all.