This gauge identifies the local slot number associated with the physical Fibre Channel endpoint representing one FC-facing port on the fabric interconnect, together with the neighbor device it discovers on the wire. An administrator locating hardware to service uses slotId on this PhysFcEp instance together with chassisId and portId to identify the exact physical location. For example, slotId tells a field technician which specific expansion module in a chassis houses the port that this PhysFcEp instance describes.