code: function(containerID, options) {
          OpenLayers.Renderer.prototype.initialize.apply(this, arguments);
  
          this.rendererRoot = this.createRenderRoot();
          this.root = this.createRoot("_root");
          this.vectorRoot = this.createRoot("_vroot");
          this.textRoot = this.createRoot("_troot");
          
          this.root.appendChild(this.vectorRoot);
          this.root.appendChild(this.textRoot);
          
          this.rendererRoot.appendChild(this.root);
          this.container.appendChild(this.rendererRoot);
          
          if(options && (options.zIndexing || options.yOrdering)) {
              this.indexer = new OpenLayers.ElementsIndexer(options.yOrdering);
          }
      }
docs: Constructor: OpenLayers.Renderer.Elements
  
  Parameters:
  containerID - {String}
  options - {Object} options for this renderer.
  
  Supported options are:
  yOrdering - {Boolean} Whether to use y-ordering
  zIndexing - {Boolean} Whether to use z-indexing. Will be ignored
  if yOrdering is set to true.