To update the cOptionData symbol settings most of the time you can use SMART for the index exchange and SMART for the option exchange. In some cases SMART will not work and you will have to lookup the correct exchanges. The easiest way to do this is to use Interactive Brokers Symbol Database.
Just press search (do not enter a value)
Enter “Alfen” here and press search
Press “Stock(2)” to find the exchange for the stock -> in this case “AEB” (under Exchange)
Press “Option(274)” to find the exchange for the option -> in this case “DTB” (under Exchanges)
To update the symbol in cOptionData, please use: