. . . "n example of a combined switch and service processor module for mounting in the shelf of FIG. 2; [0017]FIG. 7 is a schematic perspective view of an example of a power supply module for mounting in the shelf of FIG. 2; [0018]FIGS. 8A, 8B and 8C are a schematic plan view and schematic perspective views, respectively, of an example of the chassis and midplane of the shelf of FIG. 2; [0019]FIG. 8D is" . .