3Com HiPer DSP Getting Started Manual page 10

Install the NAC with or without power applied to the chassis.
3 Select a slot at the front of the Total Control chassis for installing the
NAC.
Install this NAC in slot(s): 1–17
For managed chassis, slot 17 is reserved for the Network Management
Card (NMC) NAC.
4 Use a #2 Phillips screwdriver to remove the safety panel covering this slot.
Installation Procedure 2-3