Leave room in between slot numbers. If you use every number (1 through 10) and then you get a new item in slot 3, you have to change all of the numbers 2 and up. Instead, Oracle recommends creating slot numbers with spaces; for example, 10, 20, 30, 40, and so on. Then, when you need to add a new item, it can be designated slot 15 or slot 22.