Toyota 1998 Sienna Owner's Manual page 56

Two buckles and tabs for second right
side seat belt
The 2 tabs have different shape for its
end so that the belt is not buckled in the
wrong place.
Buckle 1—Properly matches with con-
cave end tab
Buckle 2—Properly matches with round
end tab
56
CAUTION
Make sure the both buckles are cor-
rectly located and securely latched.
Failure to properly match the buckle
and tab may cause serious injury in
case of an accident or a collision.
name. SIENNA (U)
To release the concave end tab (1), press
the buckle−release button with the round
end tab (2).