One UTF-8 character encoding declaration

Class

C3 Standard

Weight

2

Severity on fail

minor

Applies to

the HTML Standard

Scope and evidence

Evaluated on page (P). The book marks this requirement STANDARD.

Fail conditions

Each condition has a stable code and a reason template. The evaluator fills the placeholders from observed values only; no sentence in a report is generated.

• multiple_charset_meta

  {url} has {n} <meta charset> elements. The HTML Standard allows no more than one meta element with a charset attribute per document.

• not_utf8

  {url} declares or uses the encoding “{label}”. The HTML Standard notes that the Encoding Standard requires UTF-8.

• declaration_too_late

  The character encoding declaration on {url} ends at byte {offset}. The HTML Standard requires it to be serialized completely within the first 1024 bytes.

The documented fix

Emit <meta charset="utf-8"> as the first child of <head>, once, and serve Content-Type: text/html; charset=utf-8.

Sources, quoted

These are the passages the rule rests on, stored once in the knowledge base and emitted exactly as written. A citation marked for specific conditions appears only on findings with those codes.

• “There must not be more than one meta element with a charset attribute per document.”

  [WHATWG-SEM] HTML Standard: 4.2 Document metadata (and 4.1 The document element) · Specifying the document's character encoding · last updated Living Standard

  https://html.spec.whatwg.org/multipage/semantics.html

• “The Encoding standard requires use of the UTF-8 character encoding and requires use of the "utf-8" encoding label to identify it.”

  [WHATWG-SEM] HTML Standard: 4.2 Document metadata (and 4.1 The document element) · Specifying the document's character encoding · last updated Living Standard

  https://html.spec.whatwg.org/multipage/semantics.html

• “The element containing the character encoding declaration must be serialized completely within the first 1024 bytes of the document.”

  [WHATWG-SEM] HTML Standard: 4.2 Document metadata (and 4.1 The document element) · Specifying the document's character encoding · last updated Living Standard

  https://html.spec.whatwg.org/multipage/semantics.html