public function add($field, $direction)
	{
		$this->orderRules[] = array(
				self::FIELD_POS => $field,
				self::DIRECTION_POS => $direction
		);
	}
public function add($field, $direction)
	{
		$this->orderRules[] = array(
				self::FIELD_POS => $field,
				self::DIRECTION_POS => $direction
		);
	}
public function add ( $ field , $ direction ) { $ this -> orderRules [ ] = array ( self :: FIELD_POS => $ field , self :: DIRECTION_POS => $ direction ) ; }
Add sorting rule
@param string $field
@param integer $direction
Add sorting rule