How many push buttons for the Ardustation

How many push buttons should the ArduStation have 5 or six, I have ordered two ArduStation and both have come with just 5 push buttons but there are places for 6 push buttons on the board and all photos of the ArduStation show 6 push buttons being used. Can some one advice please. I have not assembled them yet, just going of the picture attached and some of the other pictures on the site.

I can source the push button locally, so I not to worried about the missing ones.

Thanks