Provides a data model for system-related information.
rpcs: +---x get-system-uptime +--ro output +--ro show-system-uptime | +--ro days? common-def:time-interval-day | +--ro hours? common-def:time-interval-hour | +--ro minutes? common-def:time-interval-minute | +--ro seconds? common-def:time-interval-sec +--ro cmd-error? string