A common type of split seat is the 60/40. We often need to know whether the 60 section is on the driver or passenger side. (Some retailers use the term 40/60 for one of those options.) A few vehicles have a seat which splits in the center, called a 50/50.
Note that 60/40 is approximate; in some seats the ratio varies, but one side is wider than the other. (Some manufacturers may call it a 70/30.)
60/40 seats may have a large center armrest, small armrests,