Closes #2279

Clarify ModelicaAllocateString

chapters/functions.tex

@@ -2435,10 +2435,8 @@ \subsection{Utility Functions}\doublelabel{utility-functions}
 \lstinline!ModelicaAllocateString! & 
 \begin{tabular}{@{}p{8.cm}@{}}
 \emph{char* ModelicaAllocateString(size\_t len)} \\
-Allocate memory for a Modelica string which is used as return argument
-of an external Modelica function. Note, that the storage for string
-arrays (= pointer to string array) is still provided by the calling
-program, as for any other array. If an error occurs, this function does
+Allocate memory for a non-literal string which is used as a return argument of an external Modelica function.
+If an error occurs, this function does
 not return, but calls "\lstinline!ModelicaError!".
 \end{tabular}\\ \hline
 \lstinline!ModelicaAllocateStringWithErrorReturn! & 
@@ -2453,6 +2451,13 @@ \subsection{Utility Functions}\doublelabel{utility-functions}
 \end{tabular}\\ \hline
 \end{longtable}
 
+The valid return values for an external function returning a string are:
+\begin{itemize}
+\item A literal string.
+\item A string given as String input to the external function
+\item A string pointer returned by \lstinline!ModelicaAllocateString! or \lstinline!ModelicaAllocateStringWithErrorReturn!.
+\end{itemize}
+
 \subsection{External Objects}\doublelabel{external-objects}
 
 External functions may have internal memory reported between function