diff --git a/chapters/classes.tex b/chapters/classes.tex
index 3029798cf..499e92ef1 100644
--- a/chapters/classes.tex
+++ b/chapters/classes.tex
@@ -601,6 +601,11 @@ \subsection{Discrete-Time Variables}\label{discrete-time-variables}
 A \lstinline!Real! variable assigned in a \lstinline!when!-clause is a discrete-time variable, even though it was not declared with the prefix \lstinline!discrete!.
 A \lstinline!Real! variable not assigned in any \lstinline!when!-clause and without any type prefix is a continuous-time variable.
 
+The determination of whether a variable is assigned in \lstinline!when!-clause requires evaluating the controlling conditions of any enclosing \lstinline!if!-equations and \lstinline!for!-equations, \cref{where-a-when-equation-may-occur}.
+\begin{nonnormative}
+Checking whether a \lstinline!Real! variable declared as \lstinline!discrete! is assigned in a \lstinline!when!-clause for other valid values of controlling conditions is a quality of implementation issue for tools.
+\end{nonnormative}
+
 The default variability for \lstinline!Integer!, \lstinline!String!, \lstinline!Boolean!, or \lstinline!enumeration! variables is discrete-time, and it is not possible to declare continuous-time \lstinline!Integer!, \lstinline!String!, \lstinline!Boolean!, or \lstinline!enumeration! variables.
 
 \begin{nonnormative}
diff --git a/chapters/equations.tex b/chapters/equations.tex
index d85574de4..7ec6cec86 100644
--- a/chapters/equations.tex
+++ b/chapters/equations.tex
@@ -182,6 +182,7 @@ \subsection{If-Equations}\label{if-equations}
 The bodies that are not selected have no effect on that model evaluation.
 
 The \lstinline!if!-equations in equation sections which do not have exclusively parameter expressions as switching conditions shall have the same number of equations in each branch (a missing else is counted as zero equations and the number of equations is defined after expanding the equations to scalar equations).
+Additional restrictions apply in combination with \lstinline!when!-equations, see \cref{where-a-when-equation-may-occur} and \cref{equations-within-when-equations}.
 
 \begin{nonnormative}
 If this condition is violated, the single assignment rule would not hold, because the number of equations may change during simulation although the number of unknowns remains the same.