Roman marker numbering with Endfloat

Question

How come this doesn't change the marker numbering to roman from arabic in Endfloat?

\documentclass[a4paper,12pt,twoside]{book}
\usepackage{graphicx}
\usepackage[nolists]{endfloat}


\renewcommand{\theposttbl}{\Roman{theposttbl}}
\renewcommand{\thepostfig}{\Roman{postfig}}

\begin{document}
\chapter{This is Chapter 1}
Some text in chapter 1.  See my figure \ref{fig:MyFigure}.

\begin{figure}
                \centering
                \includegraphics{histoOne1}
                \caption{My caption for this figure}
                \label{fig:MyFigure}
\end{figure}

\let\cleardoublepage\clearpage
\chapter{This is Chapter 2}
Some text in chapter 2. 

\end{document}

Answer 1

The command to renew is \thepostfigure (and \theposttable for tables):

\documentclass[a4paper,12pt,twoside]{book}
\usepackage[demo]{graphicx}
\usepackage[nolists]{endfloat}


\renewcommand{\theposttable}{\Roman{posttbl}}
\renewcommand{\thepostfigure}{\Roman{postfig}}
\renewcommand{\thefigure}{\Roman{figure}}
\renewcommand{\thetable}{\Roman{table}}

\begin{document}

\chapter{This is Chapter 1}
Some text in chapter 1.  See my figure \ref{fig:MyFigure}.

\begin{figure}
                \centering
                \includegraphics{histoOne1}
                \caption{My caption for this figure}
                \label{fig:MyFigure}
\end{figure}

\let\cleardoublepage\clearpage
\chapter{This is Chapter 2}
Some text in chapter 2.

\end{document}