QOS - Multilayer Switch QoS (MLS)
Multilayer Switch QoS or MLS is a framework of QoS mechanisms that can be employed on a multilayer switch. Such mechanisms are employed using the mls qos command.
MLS has largely been superseded by Modular QoS CLI or MQC.
Links:
https://networklessons.com/quality-of-service/how-to-configure-qos-trust-boundary-on-cisco-switches