function _processCollectedTags($source)
        {
            $to_replace = array();
            $ordered = array();
            foreach(self::$tag_collections as $tag_name=>$tags)
            {
//              if this block has a collection order use it
                if(isset(self::$_tag_order[$tag_name]) === true)
                {
                    $pos = self::$_tag_order[$tag_name];
                    $ordered[$pos] = $tags;
                    continue;
                }
//              the source should be modified by the collection script
                $tag_func_name = ucwords(str_replace(array('_', '-'), ' ', $tag_name));
                $tag_func_name = strtolower(substr($tag_func_name, 0, 1)).substr($tag_func_name, 1);
                $tag_func_name = str_replace(' ', '', $this->_options['tag_callback_prefix'].$tag_func_name);
                if($this->_options['tag_global_callback'] !== false)
                {
                    $tags = call_user_func($this->_options['tag_global_callback'], 'collection', $tag_func_name, $tags, $source);
                }
                else
                {
                    $tags = call_user_func($tag_func_name, $tags, $source);
                }
                
                if($tags === -1)
                {
                    $source = self::throwError($tag_name, 'tag collection parsed however callback "'.$tag_func_name.'" returned -1.');
                }
                else if(is_array($tags) === false)
                {
                    $source = self::throwError($tag_name, 'tag collection parsed however callback "'.$tag_func_name.'" did not return the array of process tags.');
                }
                else if(count($tags) > 0)
                {
//                  input the parsed tags back into the source or store for re-intergration
                    foreach ($tags as $key => $tag)
                    {
                        if(strpos($source, $tag['tag']) !== false)
                        {
                            $source = str_replace($tag['tag'], $tag['parsed'], $source);
                        }
                        else
                        {
//                          do a reverse tag lookup here as the tag was not found in the source, thus it must be buried and un processed
                            array_push($to_replace, $tag);
                        }
                    }
                }
            }
            foreach($ordered as $key=>$tags)
            {
//              the source should be modified by the collection script
                $tag_func_name = ucwords(str_replace(array('_', '-'), ' ', $tag_name));
                $tag_func_name = strtolower(substr($tag_func_name, 0, 1)).substr($tag_func_name, 1);
                $tag_func_name = str_replace(' ', '', $this->_options['tag_callback_prefix'].$tag_func_name);
                $tags = call_user_func($tag_func_name, $tags);
                if($tags === -1)
                {
                    $source = self::throwError($tag['name'], 'tag collection parsed however callback "'.$tag_func_name.'" returned -1.');
                }
            }
            return $this->_doBuriedReplacements($to_replace, $source);
        }