This read-create integer (1-256) selects the upstream CAR (Committed Access Rate/rate-limit) index applied to traffic on this GEM port, policing that port's upstream flow independently of the T-CONT's overall bandwidth allocation. Admins use a restrictive CAR index on lower-priority GEM ports to keep them from crowding out a subscriber's primary data GEM port. For example, applying a low-rate UpCar index to a management-traffic GEM port prevents it from consuming upstream capacity that should be reserved for the subscriber's main data GEM port.