It's basically same as the Gregorian, but add ten thousand to every positive year. 1 A.D. is year 10.000 in this calendar. We are now in year 12.015. Founding of Rome is 9.248. What good it does? Gets rid of the A.D.-B.C. confusion, for the most part of human history. Cons? Big years. IMO, I like it, it can be adopted as an international calendar (just like Esperanto is being widely spoken by the international community, eh).