Use given name of rule in example with record equations

chapters/operatorsandexpressions.tex

@@ -1527,7 +1527,7 @@ \subsection{Discrete-Time Expressions}\label{discrete-time-expressions}
 \end{nonnormative}
 
 \begin{example}
-Discrete-time equation rule applied to record equations.
+Discrete-valued equation variability rule applied to record equations.
 In the first of the equations below, having a record constructor on both sides of the equation, the equation is conceptually split, and variabilities of \lstinline!time! and \lstinline!true! are considered separately.
 In the second equation, the \lstinline!makeR! function call -- regardless of inlining -- means that the equation cannot be conceptually split into individual record members.
 The variability of the \lstinline!makeR! call is continuous-time due to the \lstinline!time! argument, which also becomes the variability of the \lstinline!b! member of the call.