This read-create value identifies which traffic profile, by its pdnDot1dTrafficProfileIndex, is mapped to this bridge port and subport combination. An admin sets it to bind a specific subscriber port/subport to a previously defined traffic profile, determining what rate limit and traffic class apply to that subport's traffic. Writing the index for the "VoiceGold" profile onto subport 2 of a given bridge port applies that profile's voice classification and rate limit to all traffic on that subport.