b dvntn s systm f dvntn sd n th trdtnl Yrb rlgn nd n Yrb-drvd fr-mrcn rlgns. n Yrblnd, t ss plm r kl nts; n Ltn mrc nd th Crbbn t ss fr pcs f ccnt. b dvntn ls ntrcnnctd wth f nd w Pl