function is_available() {
		if ($this->_is_available === null) {
			$this->_is_available = true;
 
			$el = $this->element();
			if ($el['ACTIVE'] == 'N')
				$this->_is_available = false;
			if ($this->quantity() == 0)
				$this->_is_available = false;
		}
 
		return $this->_is_available;
	}