anchor.diff:  </div>
   
   <script type="text/javascript">
  -    var active = undefined;
  +    var active = undefined; // the 'active' group/schema being viewed and edited
       var profile = JSON.parse('<%= profile_modifying.to_json.html_safe %>')
   
  +    /**
  +     * Set the usage info for the construct named @constrName in @grpName.
  +     */
       function setConstructUse(grpName, constrName, use) {
           profile['groups'][grpName]['constructs'][constrName]['use'] = use;
       }
   
  +    /**
  +     * Set the usage info for an attribute named @attrName of @constrName in group @grpName.
  +     * @idx is the index of the attribute in the list of attributes on the construct.
  +     */
       function setAttributeUse(grpName, constrName, attrName, idx, use) {
           var attr = profile['groups'][grpName]['constructs'][constrName]['attributes'][idx];
           if (attr['name'] === attrName) {
  
positive.code:         $(".group-accessor").find('option:first').attr('selected', 'selected');
      });
  
      $(".field-usage-selector, .attr-usage-selector").change(function(e) { // when a field/attr usage level is changed, update the row highlighting
          var thisEl = $(this);
          var groupDiv = thisEl.closest("div[data-group-safe-name]"); // group root div with groupname info
  
negative.code:         }
      }
  
      /**
       * Get the current usage setting of the construct named @constrName in group @grpName.
       */
      function getConstructUse(grpName, constrName) {
          return profile['groups'][grpName]['constructs'][constrName]['use'];
      }
  
      /**
       * jQuery handler for when the usage setting of a particular construct is changed.
       */
      $(".construct-usage-changer").click(function(evt) {
          evt.preventDefault(); // don't act like a link; we're handling this click
          var thisEl = $(this); // get this object as jQuery reference
  