+ Small fix so it compiles

docs/ref.tex

@@ -1723,7 +1723,7 @@ an object. To get the size of the class instance data, use the
 \var{TObject.InstanceSize} method.
 \end{itemize}
 \section{Methods}
-\seubsection{invocation}
+\subsection{invocation}
 Method invocaticn for classes is no different than for objects. The
 following is a valid method invocation:
 \begin{verbatim}