\chapter{Changes Since First Printing}
There have been several changes to the \exo{} API in the years since
the original \exo{} report was published.  The main changes are:
\begin{itemize}
\item Addition of Coordinate Frames.
\item Addition of node set and side set results variables.
\item Addition of element block, node set, side set, element map, and
node map names.
\item Support for very large model.
\item Efficient replication of the model definition ``genesis''
portion of the database.
\item Multiple, optional named node and element maps which can be used
for any purpose.
\item Support for ``meshes'' with no node or elements; or nodes, but
no elements.
\end{itemize}

There have also been some functions added to make it easier to write
an \exo{} database efficiently.  These include:
\begin{itemize}
\item API function to write concatenated element block information,
and
\item API function to defined all results data with one function call.
\end{itemize}