Hilmer-
>>
>>>How serious is the (relatively unlikely) possibility that a certain combination does repeat? 'Cause you could just use the rand() function to create them codes.
>>>
>>
>>As unlikely as it is, it's far easier in this case to program so that I don't have to rely on unlikeliness, but I'm inclined to paranoia. ;-)
>
>You are probably aware of the GUID function. The result is longer, (16 bytes), but it is quite safe to assume - without much programming effort - that the result is, indeed, unique.

I mentioned a couple of times conditions that make GUIDs unusable, but thanks anyway for the suggestion.