Space between \micro-prefix and rest of unit symbol with siunitx

[mhumbel]

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LaTeXML produces a U+2026 Invisible Times character between the \micro prefix and the rest of the unit symbol when using siunitx. This happens only for \micro and not for the other decimal prefixes.

While Chrome seems to display this correctly (i.e. not at all), in Firefox it gets rendered as a space. Although one could argue that this is actually a bug in Firefox, I would still advocate for changing the behavior on the LaTeXML side. I have two arguments for this:

1. Consistency: The U+2026 Invisible Times character gets inserted only after the micro-prefix and none of the other decimal prefixes.
2. Semantics: I would consider a unit with a decimal prefix more a compound symbol than a multiplication of two symbols.

Minimal working example:

\documentclass{article}
\usepackage{siunitx}
\begin{document}
\si{\micro\meter}
\end{document}

The relevant part in the HTML output is:

<math id="p1.m1" class="ltx_Math" alttext="\mathrm{\SIUnitSymbolMicro m}" display="inline"><mrow class="ltx_unit"><mi mathvariant="normal">µ</mi><mo>⁢</mo><mi mathvariant="normal">m</mi></mrow></math>

with a U+2026 Invisible Times character inside the <mo></mo>.

I used

• LaTeXML version 0.8.6
• Firefox 126.0.1
• Chrome 126.0.6478.55

[dginev]

This sounds related to #2303 .

If you use the new --noinvisibletimes option for latexmlc, you may see that behavior mitigated. Currently latexml's default MathML treatment is to err on the side of invisibly multiplied terms.

That said, requesting a binding enhancement is also reasonable, so we should leave the issue open for a bit.