Make relevant part normative

chapters/equations.tex

@@ -818,6 +818,8 @@ \section{Initialization, initial equation, and initial algorithm}\label{initiali
 \lstinline!fixed = false!) in order to compute a solution numerically.
 
 It may be difficult for a user to figure out how many initial equations have to be added, especially if the system has a higher index.
+\end{nonnormative}
+Based on these non-normative considerations we have the following rules:
 A tool may add or remove initial equations automatically such that the resulting system is structurally nonsingular.
 In these cases diagnostics are appropriate since the result is not unique and not necessarily what the user expects.
 \begin{itemize}
@@ -827,7 +829,6 @@ \section{Initialization, initial equation, and initial algorithm}\label{initiali
 \item A consistent \lstinline!start!-value or initial equation may be removed with a message/warning.
 \item Tools must not change the initialization in a way that does not satisfy the initial equations and fixed start-values.
 \end{itemize}
-\end{nonnormative}
 
 \begin{example}
 Continuous time controller initialized in steady-state: