Non-normatively mention conceptual rewriting of when-equations

chapters/dae.tex

@@ -64,6 +64,10 @@ \chapter{Modelica DAE Representation}\label{modelica-dae-representation}
   These variables change their value only at event instants $t_{\mathrm{e}}$.
   \lstinline!pre(m)! are the values of $m$ immediately before the current event occurred.
 
+  \begin{nonnormative}
+    For equations in \lstinline!when!-clauses with discrete-valued variables on the left-hand side, the form \eqref{eq:dae-discrete-valued} relies upon the conceptual rewriting of equations described in \cref{defining-when-equations-by-if-expressions-in-equality-equations}.
+  \end{nonnormative}
+
 \item
   $c(t_{\mathrm{e}})$:
   The conditions of all \lstinline!if!-expressions generated including \lstinline!when!-clauses after conversion, see \cref{when-equations}).