The one I had in my hands a couple of months ago had a standing leaf with shallow vee, and the first flip-up leaf was for the same distance (~100m?) but with the square notch IIRC.
So you could flip up the first leaf for greater perceived accuracy for a precision shot if you had time.
Additional leaves were for greater distances as per traditional leaf sights.
Think I got that right! That particular rifle is owned and shot regularly by one of the posters above, who may care to comment futher...