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\title{Why \emph{eos}? \ }
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\author{William F. Hammond}
\begin{document}
\begin{center}\LARGE\bfseries{}
Why \emph{eos}? \ 
\end{center}
\begin{center}\Large\bfseries{}
\textsl{William F. Hammond}
\end{center}

\medskip
\par{The \textsc{GELLMU} \emph{article} document type has an end-of-sentence
mark \emph{eos}, which is a defined-empty \textsc{XML} element,
corresponding to the concept of sentence in languages such as English
and French. \   But there is no provision for regarding a western
sentence itself as an \textsc{XML} element. \   Why? \ 
}
\par{There are two reasons. \ 
}
\par{Sometimes one wants to begin a \emph{display} in the middle of a
sentence. \   Then it can happen that the display is the last part of
the sentence. \   It is a formal rule of \textsc{XML} that if an element
begins inside another element, then the second element must be closed
before the first element is closed. \   Following this rule, when a
display is the last part of a sentence, the display must be ended
before the sentence is ended. \   As a consequence an \textsc{XML} processor
must usually work very hard to place the sentence-ending punctuation
mark correctly. \ 
}
\par{Is this just a technical \textsc{XML} issue? \   Not really. \ 
}
\par{The second reason for modeling an end-of-sentence mark but not a
sentence is that some literary use of a language such as English
does not actually resolve into clean sentence units even though
end-of-sentence punctuation is used. \ 
}
\par{One could argue that when a sentence is used, it could be marked up
with a \emph{sentence} element\footnote{The model would then likely
permit each of \emph{sentence} and \emph{display} to contain the
other}. \   In that event it is unlikely that authors would want to be
required to insert end-of-sentence marks explicitly. \   Moreover, there
would be something of a dilemma for the \textsc{XML} processor if it
happens to notice an item of \textsc{CDATA} at the end of a sentence
that appears to be an end-of-sentence mark. \   There would still be
the vexation caused by a display that ends a sentence. \   And would
authors use the \emph{sentence} element? \ 
}
\par{Will authors want to use the explicit \emph{eos} rather than the
simple \textsc{CDATA} punctuation mark \texttt{`.'}? \   If so, how is the
sequence \texttt{".\string<eos/\string>"} to be handled by a processor? \ 
}
\par{Authors are the end users, and authors need convenience. \   Reasonable
convenience lies in the convention that began with the dawn of the
mechanical typewriter:
\begin{quote}

A sentence is ended with a period followed either by a
newline or by two or more blank spaces. \ 

\end{quote}
}
\par{Handling this convention is not a reasonably efficient task for
an \textsc{XML} processor. \   But it works very well with a \LaTeX{}-like
markup interface for \textsc{XML}, i.e., when there is pre-processing
from \LaTeX{}-like markup to \textsc{XML} markup. \ 

}
\end{document}