\documentclass[fleqn,leqno]{article}
\usepackage{hypertlabook}
\pdftitle{ASCII Text}
\fixverbatim
\begin{popup}
\begin{verbatim*}
R ** S == LET T == {rs \in R\X S : rs[1][2] = rs[2][1]}
          IN  {<<x[1][1], x[2][2]>> : x \in T}
\end{verbatim*}
\end{popup}
\makeasciipopup