your Main/Key light is always expessed as 1
your Highlighs are always expressed to the left of the of the Main/Key
which gives you an expression of 4:1 3:1 2:1 etc.
and your shadows are expressed to the right of the Main/Key
1:2 1:3 etc
So if you have a Main ,Fill and Hightlight/Accents
you might see this
2:1:2 which is F16,F11,F8