HTML specification conformance, checked against the raw response body by a conformance parser. Rule: script-type.
Impact is importance multiplied by the confidence tier’s weight — SPECIFICATION 1.0, RESEARCH 0.7, EMERGING 0.3, EXPERIMENTAL 0.1. Two rules backed by the same class of evidence therefore always carry the same weight, which is what makes the score reproducible rather than hand-tuned.
Built at scan time by markup conformance, not from our static registry. That engine evaluates its whole rule set in one pass, so this check cannot be run on its own — it runs as part of a scan.