D: stands for 'Divided'. A dimensional mix of the two colors listed (ie: D16/22)
R: stands for 'Rooted. The rooted portion comes down about 2 inches (ie: R8-8/613)
OM: stands for 'Ombre. The ombre portion comes down about 4 inches (ie: OM2/8)
#60, #613, and #22 are all solid blondes
#60 is the lightest platinum
#613 is light golden
#22 is medium golden.
As for our divided blondes, the lightest is: #D16/22 then #D18/22, then #D14/22
D16/22 is a highlight/ lowlight best suited for light golden blondes - definitely a warmer tone!