f the above levels, the
    // corresponding archives cannot be read if the implementation level
    // for the archive object is changed.  
    ///////////////////////////////////////////////////////////////////
    // Add class information to the archive.  Class information includes
    // implementation level, class version and class name if available.
    object_class_info = 3,
};
</code></pre>
Using a macro defined in <code style="white-space: normal">level.hpp</code> we can specify
that <code style="w