\documenttype[boot.dtd]{dtd}
\doctype{test}
\dtdref{prexdt.dtd}
\cmt{A Test DTD}
\cmt{Does the recommended usage match this?
  <!DOCTYPE test SYSTEM "prexdt.dtd">
}
\begin{document}
\elt{test}{oo}{(preamble,body)}
\elt{preamble}{rr}{(a)}
\elt{body}{rr}{((p|t)*)}{    BETTER}
\enp{ts}{a|p}
\elt{(\%ts)}{rr}{(#PCDATA)*}
\elt{t}{rr}{((r)+)}
\elt{r}{oo}{((c)+)}
\elt{s}{oo}{(i,(c)*)}
\elt{c}{oo}{(#PCDATA)*}
\elt{i}{oo}{(#PCDATA)+}
\end{document}