This read-write TruthValue specifies whether a given priority level's traffic is treated as lossy or lossless in the module's flow-control scheme. An admin sets this to false for priorities carrying traffic (like storage or certain data center protocols) that cannot tolerate drops, enabling lossless (PFC-style) handling instead. For example, marking a storage-traffic priority as lossless (not lossy) ensures pause frames are used to prevent drops rather than allowing the switch to discard frames under congestion.