Allied Telesis AT-S63 - Manual (Page 138)

Chapter 12: Classifiers
138 Section II: Advanced Operations
is dictated by the QoS policy, as explained in Chapter 15, “Quality of
Service” on page 165.
In summary, a classifier is a list of variables that define a traffic flow. You
apply a classifier to an ACL or a QoS policy to define the traffic flow you
want the ACL or QoS policy to affect or control.