IBM Power System 9040-MR9 Manual page 30

Figure 14. Fully removing the disk drive backplane
g) Place the disk drive backplane on an ESD surface.
4. Install the system-to-rail locking clips onto each rail. The system-to-rail locking clips keep the front
end of the system from dislodging from the rails when you move the system into the service position.
a) On the right side of the rail, pull the blue latch marked R (A).
16 Power Systems: System backplane