code: function(evt) {
          this.modifiers = {
              multiple: this.multiple || (this.multipleKey && evt[this.multipleKey]),
              toggle: this.toggle || (this.toggleKey && evt[this.toggleKey])
          };        
      }
docs: Method: setModifiers
  Sets the multiple and toggle modifiers according to the current event
  
  Parameters:
  evt - {<OpenLayers.Event>}