GMC Cadillac CTS 2004 Owner's Manual page 59

The side impact airbag for the right front passenger and
the person seated directly behind that passenger is in
the ceiling above the side windows.
CAUTION:
{
If something is between an occupant and an
airbag, the bag might not inflate properly or it
might force the object into that person causing
severe injury or even death. The path of an
inflating airbag must be kept clear. Do not put
anything between an occupant and an airbag,
and do not attach or put anything on the
steering wheel hub or on or near any other
airbag covering. And, because your vehicle
has side impact airbags, never secure anything
to the roof of your vehicle by routing the rope
or tiedown through any door or window
opening. If you do, the path of an inflating side
impact airbag will be blocked. The path of an
inflating airbag must be kept clear.
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