Being a little pedantic on this, but... I believe character total includes the "." and the ext to = 67 char. Therefore in the case of .com, .net, and other 3 char exts, the correct number preceding the "." = 63. However w/ .us and other cc 2 letter ext the correct # = 64 and conversely, w/ .info, it would = 62.
Fairly sure this is correct, but double check me.