The generic comparison
    and hashing functions are based on this integer. When an object
    is obtained by unmarshaling, the id is refreshed, and thus
    different from the original object. As a consequence, the internal
    invariants of data structures such as hash table or sets containing
    objects are broken after unmarshaling the data structures.<br>
</div>
<div class="copyright">The present documentation is copyright Institut National de Recherche en Informatique et en Automatique (INRIA). A com