freepascal.compiler/docs/syntax/string.syn

\begin{diagram}{Character strings}{characterstrings}
\begin{mysyntdiag}
\synt{character\ string} 
\begin{rep}[b] \begin{stack} \synt{quoted\ string} \\ \synt{control\ string} \end{stack} \end{rep}
\end{mysyntdiag}
\begin{mysyntdiag}
\synt{quoted\ string} 
\lit*{'}
\begin{rep}[b] \synt{string\ character} \\  \end{rep}
\lit*{'}
\end{mysyntdiag}
\begin{mysyntdiag}
\synt{string\ character} 
\begin{stack}
\tok{ Any character except ' or CR} \\
\lit*{''}
\end{stack}
\end{mysyntdiag}
\begin{mysyntdiag}
\synt{control\ string} 
\begin{rep}[b]
\lit*{\#} \synt{unsigned\ integer} \\
\end{rep}
\end{mysyntdiag}
\end{diagram}