public function renderGroup($assets) {
		$out = array();
		if ($this->f3->get('ASSETS.trim_public_root')) {
			$basePath=$this->f3->fixslashes(realpath($this->f3->fixslashes(
				$_SERVER['DOCUMENT_ROOT'].$this->f3->get('BASE'))));
			$cDir=$this->f3->fixslashes(getcwd());
			$trimPublicDir=str_replace($cDir,'',$basePath);
		}
		foreach($assets as $asset_type=>$collection) {
			if ($this->f3->exists('ASSETS.filter.'.$asset_type,$filters)) {
				if (is_string($filters))
					$filters = $this->f3->split($filters);
				$flist=array_flip($filters);
				$filters = array_values(array_intersect_key(array_replace($flist, $this->filter), $flist));
				$collection = $this->f3->relay($filters,array($collection));
			}
			foreach($collection as $asset) {
				if (isset($asset['path'])) {
					$path = $asset['path'];
					$mtime = ($this->f3->get('ASSETS.timestamps') && $asset['origin']!='external'
						&& is_file($path)) ? '?'.filemtime($path) : '';
					$base = ($this->f3->get('ASSETS.prepend_base') && $asset['origin']!='external'
						&& is_file($path)) ? $this->f3->get('BASE').'/': '';
					if (isset($trimPublicDir) && $asset['origin']!='external')
						$path = substr($path,strlen($trimPublicDir));
					$asset['path'] = $base.$path.$mtime;
				}
				$out[]=$this->f3->call($this->formatter[$asset_type],array($asset));
			}
		}
		return "\n\t".implode("\n\t",$out)."\n";
	}