This read-write boolean flags this traffic group's queue for lossless behavior under Priority Flow Control (PFC), causing ingress thresholds to be set that trigger PFC frames on crossing, and making the queue respond to PFC frames from a neighbor; it cannot be set if any queue in the template uses a 'medium' or 'low' discard threshold, and the source DESCRIPTION notes it is not supported on all devices. An admin enables it for traffic classes, such as storage traffic, that cannot tolerate packet loss, ensuring the switch uses flow control rather than dropping packets when that queue nears capacity. For example, an admin running FCoE over Ethernet would mark the storage traffic group as lossless so PFC pauses that specific priority instead of allowing storage frames to be dropped under congestion.