\nofiles
\documentstyle[doc]{article}

^^A              !!!! Warning !!!!
^^A  Comment character in this file is ^^A not %
^^A  after doc.sty was read in.

     \DisableCrossrefs
^^A  \EnableCrossrefs               ^^A Uncomment this line if you want
                                    ^^A full crossreferences
     \OnlyDescription               ^^A Outcomment this line if you want
                                    ^^A the full article

\begin{document}
  \input{underlin.sty}
\end{document}