@parameters are the parameters for each command. You can think of each command as a method which must be passed a certain set of parameters. For example, the parameters for something like Add Item would be [int, int], the first number for the ID of the item, the second number for the amount. What is in the parameters changes for each command according to its function. I doubt there's a good tutorial anywhere on this, but you can always look at the code for each command (Interpreter 3-7) and figure out what each element in parameters does.