Anyway, if anyone wants to contribute a few comments based on the diagram it would be more than welcome.
UPDATE: I just realized that I will probably need to have different kinds of arguments :) I replaced argument list with Variable
UPDATE2: Silly me. I just realized that I don't need to keep the argument data in the instruction itself. easier this way.
UPDATE3: I reconsidered. Since the commands will be added to a vector in the Script class, it would be a lot easier for them to carry their data with them.