public function setCanonicalMethod($method)
	{
		if (array_key_exists($method, $this->c14nOptionMapping))
		{
			$this->canonicalMethod = $method;
		}
		else
		{
			trigger_error(sprintf('The chosen canonical method (%s) is not supported', $method), E_USER_WARNING);
		}
		
		return $this;
	}