All empty board slots in Enterprise systems must have either a filler panel or a load board installed. (A load board is distinguished by the presence of centerplane connectors. A filler panel has no centerplane connectors.)
Empty slots in Enterprise 5500 and 4500 systems must have a filler panel installed (Figure 3-1).
Empty slots in Enterprise 6500 systems must have a load board installed (Figure 3-2).
Load boards and filler panels are inserted into a board slot with the springfingers facing down if inserted in the front of the system; the springfingers face up if inserted in the rear of the system.