\documentclass{scrartcl}

\setcounter{secnumdepth}{2}

\begin{document}
This test document is created to test advanced TOC functionality.

\frontmatter

\section{Test section 1}

\subsection{Test sub section 1}

\section{$\alpha$}

\input{sec2.tex}

\appendix

\input{sec3}

\backmatter

\end{document}
