Association Class - the example being Supplies here. Supplier and Product are both classes that can have 0..N of each other: A Supplier class can have 0...N of Product class, and vice versa. Assocation Class can be translated into code, and how it differs from a normal class?0..N requirement between Supplier class and Product class into code? What does it mean in code? Normally I just have two files each with their own class, and then I can create them in the main file. But it seems that they must somehow depend on each other?