Yes, I have noticed that, however can only guess its meaning.
If this is an attempt of limitting "concentricity" error of dia. 8 to an axis, it is a poor try, because the print says nothing about which feature serves as a datum feature.
I thing I would go back to the customer. This looks like a special - designed for their use only. On SW 4 - Schluesselweite 4mm Hex size 4mm - Ask for more info on that. Could be Torx or any other socket. Din 267 T2 and T13 give you a lot of gen. info. If not otherwise specified tol. are as per DIN 7168 as listed in box. Material is Stainless Steel. No Grade is specified.