Dell PowerEdge 6850 Hardware Installation Manual page 14

2 Place a mark approximately 7 inches above the original mark you made
(or count up 12 holes in a rack that meets EIA-310 standards) and mark
the rack's front vertical rails with a felt-tipped pen or masking tape (if you
counted holes, place a mark just above the top hole). This mark or piece of
tape indicates where the system's upper edge will be located on the vertical
rails (see Figure 1-4).
Figure 1-4. Marking the Vertical Rails
1
1 tape on vertical rail
12
Dell™ Rack Installation Guide