This read-write bitmap, using bit values 1, 2, 4, and 8 for classes 1 through 4 respectively, selects which QoS classes on this port draw their bandwidth dynamically from the port's overall lportDataRate pool on demand, rather than having a fixed percentage permanently carved out up-front like the other classes. An admin sets specific bits here for QoS classes whose traffic is bursty or unpredictable enough that a static up-front reservation would waste capacity when that class is idle, letting the switch instead allocate bandwidth to it dynamically as needed. For example, setting lportDynamicQoSbw to include qos-class-4(8) means best-effort class-4 traffic draws bandwidth on demand from the shared pool rather than always having a fixed slice reserved for it even when class-4 traffic is momentarily idle.