NEC EXPRESS 320Lb-R - Manual (Page 275)

System Upgrade 8-37
7. Align the terminal segment of the board with the connection of the slot and insert the
board slowly into the slot.
TIPS: Check to see if the edge of the bracket (taper) is inserted into a slot of the
chassis. In the case of a long board, check also to see if its other edge is inserted into
the bracket guide.
Slots for inserting
bracket edges
Guide