This object is the on/off switch for NBAR Protocol Discovery on a specific interface, controlling whether the device actively inspects and classifies the application-layer traffic crossing that interface. It matters because Protocol Discovery consumes CPU cycles to inspect packets, so an admin typically enables it only on interfaces where visibility into application mix is actually needed rather than everywhere by default. Setting this to true on a WAN uplink interface would start populating the statistics table with per-protocol traffic breakdowns for that link; leaving it false means that interface reports no protocol statistics at all.