Class 1 is usually the private cars, e.g. sedan, wagon....
A = automatic tranmission. So no manuals
According to your question, 白牌 must not mean private cars, which is not = class 1.
白牌 is actually the Light GoodsVehicles, which is in class 2.
Even though now we have auto 白牌, e.g. Hiace, Benz.....they can only take 6 passengers, and their truck needs to be separated with a metal partition. Also they use diesel (according to law, diesel vehicles can only be approved for a licence if they are class 2 or above, so now we dont have diesel private cars except those old cars e.g. Benx 230D)
So, if you have 1A, youcan ONLY drive class 1 with an automatic transmission. Any other cars not with that catagory is not allowed.