Dormer height

Hello,

in the development plan I read the following:
"Dormers may not be higher than 1.60 m above the roof surface when measured vertically."

I don't quite understand what that means, I hope someone can help.
Based on sketch a or b? Or something completely different?

Clear and likely is a), especially because b) would allow a higher dormer according to the [B-Plan]. Do not guess and call the citizen service of your building authority.