Constrain array assignments with implicit iterators.

Closes modelica#3250

chapters/statements.tex

@@ -232,7 +232,8 @@ \subsubsection{Implicit Iteration Ranges}\label{implicit-iteration-ranges}
 \end{lstlisting}
 \end{example}
 
-The size of an array -- the iteration range -- is evaluated on entry to the \lstinline!for!-loop and the array size shall not change during the execution of the \lstinline!for!-loop.
+There may not be assignment to the entire array inside the loop, but there may be assignment to individual elements or ranges of elements.
+The size of an array -- the iteration range -- is evaluated on entry to the \lstinline!for!-loop and the array size will thus not change during the execution of the \lstinline!for!-loop.
 
 \subsubsection{Types as Iteration Ranges}\label{types-as-iteration-ranges}