Buick 2001 Regal Owner's Manual page 18

Split Folding Rear Seat
To return the seatback to its original position, push it
back up and make sure it latches.
1-6
This feature enables you to
access your trunk. Pull
forward on the seat tab,
located on the front of the
rear seatback, to fold the
seatback down.
A lock out feature is located on the rear of the seatback
when folded down. This will disengage the inside seat
tab when the release is locked. The seat will then only
open from the tab on the rear of the seatback, located
inside the trunk.