Grades. You need to add those to the numbers on each rod big end. For example if the crank says 1 1 2 1 2 1 and every rod says 0g0 your final grades would be 1 1 2 1 2 1.
The front of the crank referees to the main bearings. You need to add those numbers to the numbers etched into the block next to the girdle.