e()</code>.
 <p>
 If <code>susbtitutionHeadName()</code> is "", then this
 value can only be "##default". But the value is ignored since
 since this element is not part of susbtitution group when the
 value of <code>susbstitutionHeadName()</code> is "".
 <p>
 If <code>susbtitutionHeadName()</code> is not "" and the value is
 "##default", then the namespace name is the namespace name to
 which the package of the containing class, marked with <a href="XmlRegistry.html" title="annotation in jakarta.xml.bind.an