its like a 2nd pin system.
the game will ask you for 3 random fields (a4, g7, etc) and you have to input correct numbers on a rotary disc.
the number you can scratch directly above the matrix field, is the random seed used to generate the 100 fields and must be input into your account profile on the9 website.
this measure is to prevent trojans and keyloggers to catch your login information.
the pin1 code with random positioning for numbers was easily logged by click and key loggers and / or trojans. this one goes one step further.
Come and join on Starcraft 2 as well =]