Don't have the info infront of me now, but if I recall correctly it's an array of twelve bytes that I think (...) come straight after the extra arrows you find in section 8. They're in the same order as the gateways, 1 to 12; 0 means off, 1 means red (you can't enable green arrows on a gateway, you need extra arrows positioned over the gateway to do this). Btw I'll get to that opcode question tonight as I finally have 'net access restored @home.