Subcaptions in Hebrew XeLaTeX

Question

I have a pdfLaTeX document with lots of TikZ drawings placed in subfigures with individual captions (using the Springer class svmono). I tried to translate to Hebrew XeLaTeX using the subcaption package. It works except that the subcaptions are not numbered.

(Incompatibility of 'subcaption' package with [hebrew]{babel} seems to deal with the issue but I want subcaption not caption and I'm using polyglossia not babel.)

Here is a MWE. I tried various commands from subcaption but nothing seems to work.

\documentclass{article}
\usepackage{tikz}
\usepackage{subcaption}
\usepackage{polyglossia}  
\setmainlanguage{hebrew}
\newfontfamily{\hebrewfont}{David}[Script=Hebrew]

\begin{document}
\selectlanguage{hebrew}
מלבן גדול באיור%
~\ref{big-rectangle} 
ומלבן קטן באיור%
~\ref{small-rectangle}.

\begin{figure}
\subcaptionbox{מלבן גדול\label{big-rectangle}}
{
\begin{tikzpicture}
\draw (0,0) rectangle +(5,3);
\end{tikzpicture}
}
\subcaptionbox{מלבן קטן\label{small-rectangle}}
{
\begin{tikzpicture}
\draw (0,0) rectangle +(3,1);
\end{tikzpicture}
}
\end{figure}
\end{document}

One more question: in the command \subcaptionbox[list entry]... what does list entry mean?

Answer 1

Sorry, my bad, I didn't read the documentation thoroughly. My problem is not specific to Hebrew. I get the captions I want by adding the following to the preamble:

\DeclareCaptionSubType*{figure}
\captionsetup[subfigure]{labelformat=simple}
\renewcommand\thesubfigure{איור~\thefigure(\alph{subfigure})}

and I remove the explicit איור from the reference:

מלבן גדול ב%
\ref{big-rectangle}.
\ref{small-rectangle}
מראה מלבן גדול.

The result is: