Some colours were originally not put in the standard due to the uncertainty of the colours being from other breeds and not traditionally corso colours. There are those who argue the changes to the standard as the AKC is a newer standard than the original one, and standards undergo changes several times and they can be influenced by those in power and what they have in their kennel. Morsani with the help of a few of the pioneers in the breed wrote a great standard, that gives a good idea of what a corso should look like. It can be found on a lot of corso sites but you can also purchase Il Cane Corso and I believe it is still in there. As it is a recovered breed, boxers being only one of the breeds speculated at being used in the recovery (as well as DDB, Dane, Bullies, etc.) there are more than a few things that pop up unexpectedly. I prefer the original standard and a correct corso, too many incorrect ones being bred for less than responsible reasons and rescues are being saturated with these dogs