/// \brief Read a map graph into \p root from \p outputStream, using \p entityTable to create entities.
virtual void readGraph( scene::Node& root, TextInputStream& inputStream, EntityCreator& entityTable ) const = 0;
/// \brief Write the map graph obtained by applying \p traverse to \p root into \p outputStream.
-virtual void writeGraph( scene::Node& root, GraphTraversalFunc traverse, TextOutputStream& outputStream ) const = 0;
+virtual void writeGraph( scene::Node& root, GraphTraversalFunc traverse, TextOutputStream& outputStream, bool writeComments ) const = 0;
};