IBM Power System 9040-MR9 Manual page 31

Figure 15. Pulling the blue rail latch
b) Each side of each clip is stamped with an L and an R. For the right side of the rail, ensure that the
side stamped R is facing outward.
Figure 16. Right system-to-rail locking clip
c) While holding the blue latch (A), rotate the clip (B) into the rail until it clicks into place.
System backplane for the 9040-MR9 17