United Nation$.

So long as they remain plural, you're good to go!

While I'm inclined to agree the episodic format should be in the More Details, you do get this exact message when you try to buy it:

The above should be an adequate warning for the potential buyer to go do some homework before committing to the purchase -- the add-on details are described in the manual, with a diagram. And the Shopping Guide tells you that the manual is freely available to read, also with a diagram.

In either case, it helps if you blow!