	public static function IsTransactionValid($id, $bRemoveTransaction = true)
	{
		// Constraint the transaction file within APPROOT.'data/transactions'
		$sTransactionDir = realpath(APPROOT.'data/transactions');
		$sFilepath = utils::RealPath($sTransactionDir.'/'.$id, $sTransactionDir);
		if (($sFilepath === false) || (strlen($sTransactionDir) == strlen($sFilepath)))
		{
			return false;
		}

		clearstatcache(true, $sFilepath);
		$bResult = file_exists($sFilepath);
		if ($bResult)
		{
			if ($bRemoveTransaction)
			{
				$bResult = @unlink($sFilepath);
				if (!$bResult)
				{
					self::Error('IsTransactionValid: FAILED to remove transaction '.$id);
				}
				else
				{
					self::Info('IsTransactionValid: OK. Removed transaction: '.$id);
				}
			}
		}
		else
		{
			self::Info("IsTransactionValid: Transaction '$id' not found. Pending transactions for this user:\n".implode("\n", self::GetPendingTransactions()));
		}
		return $bResult;
	}
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.