Numeric character reference: Difference between revisions

Revision as of 20:48, 17 October 2021

Revision as of 06:26, 13 November 2021

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==Compatibility issues==

In the initial versions of [[SGML]] and [[HTML]], numeric character references were interpreted in relationship to the document character encoding, rather than [[Unicode]]. For Latin-script documents, numeric character references to characters between x80 and x9F in those documents will not be correct against [[Unicode]], and must be recoded. HTML standards prior to [[HTML 4]] only supported only Western Latin script documents: the treatment of character references above #7F may vary between applications and national conventions.

For example, as mentioned above, the correct numeric character reference for the [[Euro sign]] "€" <code>U+20AC</code> when using [[Unicode]] is decimal <code>&amp;#8364;</code> and hexadecimal <code>&amp;#x20AC;</code>. However, if using tools supporting obsolete implementations of HTML, the reference <code>&amp;#128;</code> (Euro sign in the [[Cp1252CP-1252]] code page) or <code>&amp;#164;</code> (Euro sign in [[ISO/IEC 8859-15]] ) may work.

As another example, if some text was created originally using the [[MacRoman]] character set, the [[quotation mark glyphs|left double quotation mark]] {{char|“}} will be represented with code point xD2. This will not display properly in a system expecting a document encoded as UTF-8, ISO 8859-1, or [[CP1252]]CP-1252, where this code point is occupied by the letter [[Ò]]. The correct numeric character reference for {{char|“}} in HTML 4 and newer is <code>&amp;#x201C;</code>, because [[Unicode#Upluslink|U+]]201C is its UCS code. In some systems, the [[List of XML and HTML character entity references|named character reference]] <code>&amp;ldquo;</code> may also be available.

==See also==