Chevrolet 2011 Aveo Owner's Manual page 104

3-54 Seats and Restraints
If the position you are using
does not have a headrest
or head restraint and you
are using a dual tether,
route the tether over the
seatback.
If the position you are using
has a headrest or head
restraint and you are using
a dual tether, route the
tether under the headrest
or head restraint and in
between the headrest or
head restraint posts.
If the position you are using
has an adjustable headrest
or head restraint and you
are using a single tether,
route the tether under the
headrest or head restraint
and in between the
headrest or head restraint
posts.