Allied Telesis AT-S63 - Manual (Page 128)

Chapter 11: Classifiers
128 Section II: Advanced Operations
is dictated by the QoS policy, as explained in Chapter 14, “Quality of
Service” on page 155.
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.