private function record_tag($tag)
    {
        if (isset($this->tags[$tag . 'count'])) { //check for the existence of this tag type
            $this->tags[$tag . 'count']++;
            $this->tags[$tag . $this->tags[$tag . 'count']] = $this->indent_level; //and record the present indent level
        } else { //otherwise initialize this tag type
            $this->tags[$tag . 'count'] = 1;
            $this->tags[$tag . $this->tags[$tag . 'count']] = $this->indent_level; //and record the present indent level
        }
        $this->tags[$tag . $this->tags[$tag . 'count'] . 'parent'] = $this->tags['parent']; //set the parent (i.e. in the case of a div this.tags.div1parent)
        $this->tags['parent'] = $tag . $this->tags[$tag . 'count']; //and make this the current parent (i.e. in the case of a div 'div1')
    }