R2 = 2nd Row, R3 = 3rd Row.This tells you how many seating positions you have in the 2nd row and how many in the 3rd row.Here's why you may care about this. Let's take a 7-seater vehicle. You'll always have 2 seats in front (driver & front passenger). However, the 2nd & 3rd rows can vary in a way that might make one unsuitable for your family's needs. Let's say you want to do 3-across in the 2nd row of your new 7-seater vehicle. The picture below shows two possible options for a 7-seater vehicle. If you choose a vehicle with the layout shown on the left (2 captain's chairs in the middle row) you can't do 3-across in the 2nd row as the 2nd row only has 2 seats! To do 3-across in the 2nd row you need a vehicle that looks like the one on the right - with 3 seats in the 2nd row.