Best way, to get the fare base from ticket or UA reservations desk and look it up online, like on ita or EF.
While EF is a subscription service, on ita rebook the same itinerary and it should allow you to pull up the fare rules. I do not think you can look up the routing rules on ita though, but you can pull those on EF as well.

I still think, that UA (and all airlines) should be required to afford easy access to the fare rules for any ticketed itinerary.