ign: right">The OID of the immediate parent of the class. <br/>Structural classes may only have other structural or abstract classes as their parent. <br/>Abstract classes may only have other abstract classes as a parent. <br/>For auxiliary classes, <code>subclassOf</code> may be either an auxiliary or an abstract class.</td></tr>
<tr><td style="text-align: left"><code>auxiliaryClass</code>, <code>systemAuxiliaryClass</code></td><td style="text-align: center"></td><td style="text-align: right">This pair of 