MathML Editor
Edit MathML with local XML checks, standard namespace repair and formatted markup plus native or MathJax previews for destination-ready review.{{ values.formatted_source }}| Check | Status | Evidence | Review before handoff | Copy |
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Mathematical Markup Language (MathML) represents notation as a tree of elements rather than as a flat image. An identifier such as x, an operator such as +, and a structure such as a fraction or superscript each have their own markup. That structure lets browsers lay out equations, adapt them to surrounding text, and expose mathematical content to assistive technology.
Presentation MathML describes how notation is arranged. Token elements include <mi> for identifiers, <mn> for numbers, and <mo> for operators. Layout elements combine those tokens into fractions, roots, scripts, rows, and tables. One top-level <math> element should contain the expression.
- Well-formed XML
- Tags are balanced and properly nested, attribute values are quoted, prefixes are declared, and exactly one document element is present.
- MathML namespace
- The standard MathML namespace identifies elements as MathML in namespace-aware XML.
- Visual rendering
- A renderer turns the structure into visible notation. Different browser and rendering engines may not produce identical spacing or feature support.
- Semantic quality
- The markup expresses the intended mathematics and reading order, not merely a shape that happens to look correct.
Passing an XML structure check does not prove full MathML conformance or mathematical correctness. A formula can be well formed yet use the wrong operator, group a denominator incorrectly, omit accessible context, or rely on elements the destination does not support. Visual review and destination testing remain necessary.
Formatting changes whitespace between tags, not the expression tree. Pretty printing is useful during review; compact output is useful when storage size or embedding matters. Whitespace inside text nodes is part of the source and should not be treated as disposable without understanding the target renderer.
How to Use This Tool:
Work from one complete expression and use the preview as a second check after the structure audit.
- Paste or type one expression in MathML source. To add a common token or layout, place the cursor first and use Insert structure; the source may contain up to 100,000 characters, 2,000 elements, and 64 levels of nesting.
- Choose MathJax SVG for a consistent generated SVG preview or Browser native MathML to test the current browser's built-in interpretation.
- Correct the first structure error shown. Mismatched tags, duplicate attributes, undeclared prefixes, unsupported entities, and rejected active content prevent preview and formatted output.
- Compare Rendered formula with the intended notation, then inspect Formatted MathML and Markup audit. Test the copied or downloaded markup in its real destination before handoff.
Interpreting Results:
Expression ready means the source is well formed, has a <math> root, uses the standard MathML namespace, and produced the selected preview. It does not mean every MathML rule or mathematical statement has been validated.
- Namespace added for preview means the root lacked a namespace. The standard namespace is added to the preview and formatted artifact, but the original source still needed repair.
- Nonstandard namespace leaves the declared namespace visible for review. Confirm or replace it before reuse in an XML-aware system.
- A MathJax error with a passing structure audit may indicate unsupported or semantically problematic markup. Switch to native rendering for comparison, but do not treat one successful engine as proof that every destination will agree.
- Element counts and maximum depth help spot an unexpectedly large or nested expression. They are complexity clues, not quality scores.
Technical Details:
The audit uses a bounded XML-oriented parser built for one MathML expression. It tokenizes text, comments, CDATA, processing instructions, start tags, and end tags; tracks namespace declarations and open elements; then builds element-frequency and depth metrics. It does not apply the complete MathML schema.
Transformation Core:
The same parsed token stream produces the formatted artifact and the preview source. An existing XML declaration is removed from that token stream and re-added only when XML declaration is enabled.
| Stage | Transformation | Important boundary |
|---|---|---|
| Normalize | Remove a leading byte-order mark, normalize line endings, and trim outer whitespace | Text inside the document remains part of the token stream |
| Parse | Check XML names, attributes, entities, namespaces, nesting, and one-root structure | This is bounded structural validation, not a complete MathML schema check |
| Repair namespace | Add the standard default namespace when the root is <math> and no namespace is declared | A nonstandard declared namespace is reported rather than silently replaced |
| Format | Pretty print with two-space indentation or remove whitespace that occurs only between tags | Token text and quoted attribute values are not rewritten |
| Render | Send compact reviewed markup to MathJax or the native browser renderer | Preview scale changes only the on-page size |
Rule Core:
The safety filter narrows what can enter the local preview. It rejects constructs that could introduce active or foreign embedded content, but that filter is not a general-purpose sanitizer for arbitrary HTML or XML.
| Rule | Accepted | Rejected |
|---|---|---|
| Document shape | One balanced document element | Text outside the root, multiple roots, mismatched or unclosed tags |
| Attributes | Unique XML names with quoted values and declared prefixes | Duplicate attributes, unquoted values, undeclared prefixes, event attributes, href, src, style, or formaction |
| Entities | The five predefined XML entities and legal numeric character references | Other named entities, illegal code points, DTDs, and entity declarations |
| Elements | Ordinary XML element names within the bounds | Active and foreign elements including scripts, styles, frames, forms, images, SVG, and foreign objects |
| Resource limits | At most 100,000 characters, 2,000 elements, and depth 64 | Any source exceeding one of those inclusive maximums |
Formula Core:
The review count has two binary terms: one for a root other than <math> and one for a namespace other than the standard MathML namespace. It therefore ranges from 0 to 2.
Element count increments for every start or self-closing tag. Maximum depth is the largest number of open elements after a start tag is read. Attribute count sums all attributes, including namespace declarations, and text-node count includes nonblank text and nonblank CDATA sections.
For a missing namespace on a valid <math> root, R equals 1. The formatted output adds the standard default namespace, so the repaired artifact can reach a zero-review structure when parsed again.
Security and Compatibility Notes:
Parsing, formatting, and native preview happen in the browser tab. MathJax preview requires the configured external renderer to load, and its availability is separate from the local structure audit.
The rejected-element and attribute rules reduce active-content risk in the preview, but they do not turn the editor into a complete security sanitizer. Apply the receiving application's own allowlist, Content Security Policy, and trusted rendering path before accepting untrusted markup.
Rendering can differ across browsers, assistive technologies, publishing systems, and MathJax versions. Verify visual layout, spoken interpretation, line breaking, and unsupported elements in the actual destination, especially for complex tables, scripts, and operators.
References:
- MathML Core, W3C, 24 June 2025.
- Namespaces in XML 1.0, W3C, 8 December 2009.