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\title{The Use of SGML Entities in GELLMU}
\date{21 July 2000}
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\author{William F. Hammond}
\begin{document}
\begin{center}\LARGE\bfseries{}
The Use of SGML Entities in GELLMU
\end{center}
\begin{center}\Large\bfseries{}
\textsl{William F. Hammond}
\end{center}
\begin{center}
\large\bfseries{}
21 July 2000
\end{center}

\medskip

\section*{1\ \ \label{SU-1}Introduction}
\par{\textsc{GELLMU} now has provision for the incorporation of an
internal declaration subset with either \textsc{SGML} or direct \textsc{XML}
output from the syntactic translator \textsl{gellmu.el}. \   (The didatic
\emph{article} document type is first written as \textsc{SGML} and then
re-formatted with some normalization, including ``argument
naming'', as \textsc{XML}.)
}
\par{SGML entities do not correspond in any obvious way to classical
LaTeX markup. \   However, as things unfold, it is expected that
use of SGML entities may accommodate \emph{some} \LaTeX{}-like
macro functionality. \ 
}
\par{As things stand with the didactic document type, all entity expansion
takes place when the SGML created by \textsl{gellmu.el} is first
parsed. \ 
}
\par{With an appropriate \textsc{SGML} document type defintion, one might
provide for an ``internal'' command in the article preamble
that spawns an internal declaration subset in the \textsc{XML} image. \ 
For direct production of \textsc{XML} this is not an issue. \ 
}
\par{These two ways of handling entities could be used in the same
document. \ 

}

\section*{2\ \ \label{SU-2}A Few Simple Examples}
\par{The quoted phrase at the end of this sentence is produced with entity
markup under the name \emph{foo}: ``a \textless{}sample\textgreater{} string''. \   The GELLMU source
used for this phrase is \texttt{"\&foo"}. \ 
}
\par{The \textsc{GELLMU} source for the definition of the entity \emph{foo}
is \begin{center}
\verb+\entity{foo "a &oltc;sample&ogtc; string"}+\ . \ 
\end{center} Note that \emph{sample} is not
markup. \   The expansion of this definition uses another entity
\emph{fooglm}. \   The entity \emph{oltc} is defined in the source with
\begin{center}
\verb+\entity{oltc STARTTAG "ltc"}+\ . \ 
\end{center}
It invokes at parse-time the starttag for the empty element \emph{ltc}
in the didactic \textsc{GELLMU} document type that gives rise in most
formattings to the character \texttt{`\string<'}. \   Note that this layer of
indirection is only required for an \textsc{SGML} (or \textsc{XML}) document
that is going to be subjected to a formatting pipeline that involves
at least one target language under \textsc{SGML} or \textsc{XML} where
an instance of the character \texttt{`\string<'} might not be intended as markup. \ 
}
\par{The \textsc{GELLMU} source for the definition of \emph{foo} translates
under \textsl{gellmu.el} to SGML as \begin{center}
\verb+<!ENTITY foo "a &oltc;sample&ogtc; string">+\ . \ 
\end{center} The
display of this translation is marked up with still another entity
\emph{foosgml}. \ 

}
\end{document}