orting
    this concept. It may be used more than once to specify multiple
    permissions.</td></tr>
    
  <!-- ========== Formal Conditions ========== -->
  <tr><th colspan="2" align="left">Formal Conditions</th></tr>
  <tr><td width="10%" align="left" valign="top">
  <code>@<b>requires</b>:</code>&nbsp;... </td><td> 
    A requirement for using an object.  Multiple <code>requires</code>
    fields may be used if an object has multiple
    requirements.</td></tr>
    
  <tr><td width="10%" align="left" v