I need to produce a madda sign without any preceding fatha, just the madda. I can't understand why the MWE below stubbornly produces a vowel above the mim, as in the following image.

%!TEX TS-program = xelatex
%!TEX encoding = UTF-8 Unicode
\documentclass{article}
\usepackage{fontspec}
\usepackage[novoc]{arabxetex}
\begin{document}

\begin{arab}
al-asm^A
\end{arab}
\end{document}


I've tried playing around with the quotation mark and whatnot, to no avail. I wonder if someone could try? Dirty fixes are welcome too. Thanks, J

The explanation of ArabTeX’s input convention in the ArabTeX documentation suggests, none too clearly, that ^A is useful for reproducing some historic spellings, and that 'A is more generally useful.

\documentclass{article}
\usepackage{fontspec}
\usepackage[novoc]{arabxetex}

Even when using arabxetex, the documentation for ArabTeX is often essential; the former seems to assume it and not to repeat everything useful.