public function setDocType( $doctype )
	{
		$doctypes	= array_keys( $this->doctypes );
		$key		= str_replace( array( ' ', '-' ), '_', trim( $doctype ) );
		$key		= preg_replace( "/[^A-Z0-9_]/", '', strtoupper( $key ) );
		if( !strlen( trim( $key ) ) )
			throw new InvalidArgumentException( 'No doctype given' );
		if( !array_key_exists( $key, $this->doctypes ) )
			throw new OutOfRangeException( 'Doctype "'.$doctype.'" (understood as '.$key.') is invalid' );
		$this->doctype	= $key;
	}