Cadillac 1999 Seville Owner's Manual page 55

Master Key
There is a master key that works in all of the lock
cylinders (driver's door, trunk, ignition and glove box).
There is also a valet key which only operates the
driver's door and the ignition.
Both the master and valet keys have a transponder
embedded into the key for security and theft deterrence.
The keys also come with a bar code tag. Keep the bar
code tag in a safe place. If you lose your key you will be
able to have a new one made using the bar code tag.
The replacement key must have a transponder embedded
in it.
Your vehicle has a number of new features that
can help prevent theft. You can have a lot of
Valet Key
trouble getting into your vehicle if you ever lock
your key inside and you may have to damage
your vehicle to get in. Be sure you have an
extra key.
NOTICE:
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