Octet sequence {octets} is not an allowed representation of the character {char} — character reference {char:hexref} should be used instead.

No character is assigned to octet sequence {octets}.

Octet sequence {octets} is illegal.

The input stream is broken.

The input stream is encoded in ISO-2022-JP or its variant but is partially broken.

Note that an ISO-2022-JP stream must end in the ASCII state.

No character is assigned to octet sequence {octets}.

Character encoding {value} is not supported and the explicit character encoding specification is ignored. The result of the conformance checking might be wrong.

Character encoding {text} is not allowed for HTML document.

The character encoding used for the document is not allowed for HTML document. The document is non‐conforming.

Character encoding {text} should not be used for HTML document.

The character encoding used for the document is not recommended for HTML document. The document is non‐conforming unless there is any good reason to use that encoding.

Use of UTF-8 is encouraged (this document is encoded in {text}).

Use of UTF-8 as the character encoding of the document is encouraged, though the use of another character encoding is still conforming.

Conformance for character encoding requirements cannot be checked, since the input is not a byte stream.

The conformance checker cannot detect whether the input document met the requirements on character encoding, since the document is not inputed as a serialized byte sequence. The document is not conforming if it is not encoded in an appropriate character encoding with appropriate labeling.

There is no character encoding declaration.

The document does not contain a character encoding declaration. Unless the character encoding is explicitly specified in lower‐level protocol, e.g. in HTTP, or is implied by BOM, there must be a character encoding declaration. The document is non‐conforming.

The long character encoding declaration syntax <meta http-equiv="Content-Type" content="text/html; charset=charset-name"> is obsolete. The new syntax is:

<meta charset="charset-name">

Note that the encoding declaration in XML declaration has no effect for HTML document.

No character encoding metadata is found in lower‐level protocol nor is there BOM, while character encoding {text} is not a superset of ASCII.

The document is not labeled with character encoding name in lower‐level protocol, e.g. in HTTP, and the document is not begin with BOM. In addition, the character encoding of the document is not a superset of ASCII. The document is non‐conforming.

Unless there is a BOM, the character encoding for the document must be specified in e.g. HTTP‐level, as:

Content-Type: text/html; charset=charset-name

Existence of HTML character encoding declaration, i.e. <meta charset="charset-name">, does not allow to omit charset parameter for HTML document encoded in non‐ASCII compatible encoding.

Character encodings Shift_JIS, Windows-31J, and ISO-2022-JP are not a superset of ASCII for the purpose of HTML conformance.

Character encoding of this document is sniffed as {text} (Sniffed because no explicit specification for the character encoding of this document is found in the transfer procotol headers).

Character encoding of this document is defaulted to {text} because no explicit specification for the character encoding of this document is found in the transfer procotol headers.

Results might be wrong, since the conformance checker cannot find an appropriate decoder for the character encoding used for the document.

The conformance checker cannot find an appropriate decoder for the character encoding used to encode characters in the document.

This error is raised if:

• the conformance checker cannot find any decoder for the character encoding in use, but it knows that the encoding is similar to another character encoding, such that it uses the decoder for that character encoding, and therefore some octets might be interpreted incorrectly, or,
• the conformance checker find a decoder for the character encoding in use, but it does not know whether the decoder is conforming to the relevant specification or not, and therefore some octets might be in