This read-write integer gives the minimum guaranteed throughput percentage for this tentative service class's queue on each output port, with zero meaning no guarantee, and the field is locked out under specific priority/DiffServ combinations noted in its own description. It lets an admin reserve bandwidth for an important traffic class so it isn't starved when the port is congested. For example, setting this to 20 guarantees the class at least 20% of a port's throughput even during heavy contention from other queues.