Well, my local (FCC) machine is hardly clear about restrictions. Here's a description. And bear in mind that the ticket office is open very limited hours.
You can buy a ticket for the next morning, but that's peak only during the week. It doesn't warn you when you've selected a ticket for tomorrow, meaning that if somebody's selected it before you arrive without cancelling, you're inadvertently buying a ticket for tomorrow, not today as you'd expect (as has happened before).
If, however, you select a ticket for today, the front screen will display a selection appropriate to the time of day. If you drill down to the "search by destination" screen, however, it will offer all tickets valid on that day (so it will offer an off-peak ticket in the peak, but it won't offer a super off-peak ticket at the weekend).
If you select an off-peak ticket, it will give the following explanation (roughly):
"Outbound: Valid at and after 0930, with exceptions.
Return: Valid at and after 0930, some evening restrictions."
Nowhere outside the (locked most of the day) ticket office are these exceptions or restrictions displayed. You could be forgiven for thinking that, if they're being offered, they're valid right now.
If you want to buy a child ticket, you can't. Not without an adult ticket, anyway. Nowhere does it explain this, or tell children what they're supposed to do to avoid a penalty fare.
At weekends, Super Off-Peak fares are offered, but only underneath the Off-Peak fares (why would you buy these?) if you drill down. On the non-weekend days where Super Off-Peak fares are valid (usually during the summer), the ticket machines do not offer them, so you have to buy the more expensive fare.
Oh, and if you select a railcard with a minimum fare, it'll show you the minimum fare, rather than the non-railcard fare, even if the latter is cheaper.
Not particularly impressive. I regularly have to help out people who are utterly confused by them (often when I'm just walking past!)