Arosa: Ge 4/4 Head And Taillight Controls

Can anyone explain to me what each position of the three switches actually does? I can't seem to figure it out, and the manual is no help.

 

Here is some information:
Signals on vehicles (styria-mobile.at)

 

Well, that helps with what lights are used when, but not how to turn them on.

it would be simple if one switch mapped to one set of lights, but the three seem to be interactive