. "f FIG. 2; [0032]FIG. 6 is a schematic perspective view of an example of a combined switch and service processor module for mounting in the shelf of FIG. 2; [0033]FIG. 7 is a schematic perspective view of an example of a power supply module for mounting in the shelf of FIG. 2; [0034]FIGS. 8A, 8B and 8C are a schematic plan view and schematic perspective views, respectively, of an example of the cha" . . .