# Usage of \Umathaccent

can someone clarify how to use \Umathaccent. The luatex manual is very terse on the topic and trying to quickly replicate examples such as \Umathaccent 0 0 "020D7 {example} leads to an error just after the " namely Missing number, treated as zero.

Example:

\documentclass{article}
\usepackage{unicode-math}

\begin{document}

$\Umathaccent 0 2 "20D7 a$

$\Umathaccent 0 2 "20D7 {example}$

\end{document}


The first number is essentially ignored, for the class of the symbol is irrelevant. The second number is the math family the accent should be taken from, the third number is the slot in the font. What the accent is placed upon follows.

The first number exists for compatibility with \Umathchar.

• grr I guess you were quicker, I'll delete:-) – David Carlisle Oct 25 '20 at 15:58
• @egreg thanks... now it is clear... I could not figure out the role of the second number. And I could not experiment either because I was doing so inside a document where I was loading something that was introducing a \setactivedoublequote... – Callegar Oct 25 '20 at 20:38
• @Callegar In case of doubts, you can do \string" – egreg Oct 25 '20 at 20:43