Oh also, here's a situation to watch for. Last trip we were on about our 52nd revision to the trip. We ended up flying from the overnight to Atlanta, doing a mx verification flight, a day layover, then flying to the next overnight. On the last leg I was showing the math behind the LATT times to the other guy when I noticed they were way off. The LATT said our latest TO time was five minutes before our dropdead time (essentially showing us we had 3 hours more than we actually did). Long story short, I assumed it was my public math, but it was still bugging me. So I ran the calculations a couple of times. It still didn't compute. I ended up calling the duty pilot because I was sure it was wrong. He came up with the same result as me. I asked if he would look into it and get back to me. What they found is there's a glitch in the LATT times if you gate return. Since we had a MX verification flight (ATL-ATL) it was wrong too. It was no big deal since we had plenty of time. But if you were close it could be an issue.