HTML5 MathML
HTML5 MathML open Attribute
The open attribute belongs to the <mfenced> element and sets the character used as the opening fence (bracket). It pairs with close to wrap content in a bracket pair.
Definition and Usage
By default <mfenced> opens with a round bracket (. Set open to any single character - [, {, | and so on - to change the opening fence. Since <mfenced> is deprecated, open appears mainly in older documents.
Syntax
Example
<mfenced open="{" close="}">
<mi>x</mi>
</mfenced>Example
Example
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>MathML open attribute</title>
</head>
<body>
<math display="block">
<mfenced open="{" close="}" separators=",">
<mn>1</mn>
<mn>2</mn>
<mn>3</mn>
</mfenced>
</math>
</body>
</html>⚠️
<mfenced> and its open attribute are deprecated and not in MathML Core. Prefer an explicit <mo>{</mo> opening operator.
Key Takeaways
- open sets the opening fence character on <mfenced>.
- It pairs with close to form a bracket pair.
- Deprecated - use an explicit opening <mo> instead.