public function addBlankElement($element)
    {
        if (!isset($this->info[$element])) {
            $this->elements[] = $element;
            $this->info[$element] = new HTMLPurifier_ElementDef();
            $this->info[$element]->standalone = false;
        } else {
            trigger_error("Definition for $element already exists in module, cannot redefine");
        }
        return $this->info[$element];
    }