Buick 2007 Rendezvous Owner's Manual page 150

If you do not know if your garage door opener is a
fixed code or rolling code device, open your
garage door opener's remote control battery cover.
Your garage door opener is a fixed code device
if there is a panel of switches. If not, your
garage door opener is a rolling code device.
150
Programming Universal Home
Remote — Fixed Code
Fixed Code garage door openers are used for
garage doors produced prior to 1996. Fixed code
uses the same coded signal every time, which
is manually programmed by setting DIP switches
for a unique personal code.