Rubric / Readability

Declared language

markup.language

weight 1deterministic

The document declares its language: <html lang> is present and a well-formed BCP 47 tag, and any hreflang alternates carry well-formed values. Self-referencing and reciprocity are not checked — both require fetching the alternates, and a wrong warning there would be the scanner's limit charged to the site.

Definition

Check ID

markup.language

Category

Readability

Weight

Counts toward the score

Yes.

Evaluated by

A fixed rule with no threshold of our choosing. The same input always produces the same verdict.

Standard maturity

established

Canonical spec

None. This check has no published external specification — it is an AgentSpeed rule.

Introduced in

r2026.08.1

Retired in

Still active.

History

Every change to the instrument— including the versions that changed this check

Machine-readable

/rubric.json— this check, and every other, as data

How often this check is right

No rate published. Too few labelled cases to publish a rate: 1 flagged case (30 needed to publish), 1 defective case (30 needed to publish). The counts are the honest answer here. The matrix behind markup.language is 6 labelled cases — reported here rather than turned into a percentage that would read as more certain than the evidence is.

Corpus v1, measured under rubric r2026.11.0. Full method and every other check at /rubric/accuracy.

How to fix it

Add `lang` to your `<html>` element (`<html lang="en">`, `<html lang="de-DE">`). If you publish translations, declare them with `<link rel="alternate" hreflang="..." href="...">` using BCP 47 tags — language[-Script][-REGION], hyphens not underscores.

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