Cadillac 2011 DTS Owner's Manual page 117

There is a glow-in-the-dark emergency trunk release
handle located inside the trunk near the latch. This
handle will glow following exposure to light. Pull the
release handle to open the trunk from the inside.
The vehicle has a small door in the rear seat. This door
allows access to the trunk from inside the vehicle.
The rear seat armrest must be down for the
pass-through door to open. To release the pass-through
door, move the release up. To close the door, raise it
and push it until it latches.
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