Limitation codes
 

On take off gross weight charts, there are limitation codes which tell you what is actually limiting your weight like on the ATR, 1=structure, 2=2nd segment, 3=runway etc all are pretty self explanatory except a few. On the ATR, 0=Dry check or wet check, 7= RWY 2 engine, 8= Final Take off. Can somebody explain me these codes or let me know where can I find there explanation. I will be highly grateful.