It is good to know that there is some question about parking in DC. My daughter called the traffic department this afternoon and they confirmed that a car with a disabled tag can park for free. It appears as if more than one person is poorly informed.
We have parked without paying five times since August and have never received a ticket. We left the car in the parking place a minimum of five hours on each occasion. I will likely be more careful when we return next week, as I would not like to receive a parking ticket, and I do not have anything in writing about their policy.