public function mergeIdentity($identity, $allow)
	{
		$identity = (int) $identity;
		$allow = (int) ((boolean) $allow);

		// Check that the identity exists.
		if (isset($this->data[$identity]))
		{
			// Explicit deny always wins a merge.
			if ($this->data[$identity] !== 0)
			{
				$this->data[$identity] = $allow;
			}
		}
		else
		{
			$this->data[$identity] = $allow;
		}
	}