Hydraulic Circuit Reservoirs

This part you won't miss once the bonnet is opened.
It makes part of the pressure generating circuit along with the hydraulic pump and the accumulator assembly.

Level marks are displayed on the lower side of the tank (on this picture they are shaded). The left one (facing front side of the car) goes with the front reservoir and the right (facing rear side) goes with the rear.
To check proper level you must run the engine at least 4 minutes. If necessary you can refill both reservoirs by opening the filling caps (left = front, right=rear).
Service asks for these two reservoirs to be cleaned every two year. User's handbook mentions using only Castrol-Girling Amber Brake Fluid 1738 and no way mineral oil for serial numbers prior to 50000 (Bobbitt). But that Castrol 1738 has became extinct. Read here for required Hydraulic Fluid today. Not pretty new on the picture here.