mathjax 4 issue

Open

#620 opened on Jul 1, 2026 0 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty: 4/5
Estimated time: 3-5 days
Newbie friendliness: 38/100

Issue type: Bug
Clarity: Needs clarification
Activity status: Quiet
Tech stack: rust
Domain: accessibility

Research direction

No source file or test is named. Start by tracing MathCAT's handling of the invisible operators shown in the MathJax 3 and 4 MathML examples, then determine whether both inputs can be handled on the MathCAT side; done means establishing how the two cases should be processed.

Written by the indexing model from the issue text.

Description

overline issue
In MathJax3 $\overline{GI}$ produce following mathml

<math xmlns='http://www.w3.org/1998/Math/MathML'>
 <mover>
  <mrow>
    <mi>G</mi>
    <mo>&#x2063;</mo>
    <mi>I</mi>
  </mrow>
  <mo accent='true'>¯</mo>
 </mover>
</math>

which read as line segment cap g cap i math.

In MathJax4 $\overline{GI}$ produce following mathml

<math xmlns='http://www.w3.org/1998/Math/MathML'>
 <mover>
  <mrow>
    <mi>G</mi>
    <mo>&#x2061;</mo>
    <mi>I</mi>
  </mrow>
  <mo accent='true'>¯</mo>
 </mover>
</math>

which read as quantity cap g of cap i with line above math.

mhchem water issue
In mathJax3 $\ce{H2O}$ produce following mathml

<math xmlns='http://www.w3.org/1998/Math/MathML'>
 <mrow>
  <mmultiscripts>
    <mi mathvariant='normal'>H</mi>
    <mn>2</mn>
    <none></none>
  </mmultiscripts>
  <mo>&#x2063;</mo>
  <mi mathvariant='normal'>O</mi>
 </mrow>
</math>

which read as cap h sub 2 cap o math.

In mathJax4 $\ce{H2O}$ produce following mathml

<math xmlns='http://www.w3.org/1998/Math/MathML'>
 <mrow>
  <mi mathvariant='normal'>H</mi>
  <mo>&#x2061;</mo>
  <mrow>
    <mmultiscripts>
      <mo>&#x2062;</mo>
      <mprescripts></mprescripts>
      <mn>2</mn>
      <none></none>
    </mmultiscripts>
    <mi mathvariant='normal'>O</mi>
  </mrow>
 </mrow>
</math

which read as cap h of pre sub 2 cap o math.

In both cases, output of mathjax 3 is what MathCAT expected.
In both cases ⁡ appeared in MathJax4.

What is MathCAT's solution? Can these issue be solved from MathCAT side?

Dominant language: Rust
Stars: 114
Forks: 85
Avg merge: 1d 12h
Merged PRs (30d): 64

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