[b3lha]

The JDM key has an infra-red led that transmits a code to a sensor in the driver's door handle. You need to hold it about 6 inches away and aim really carefully.

In the picture, the key on the left is a broken one from a friend's SVX (the transmitter is missing). On the right is a working one from my version L.
http://www.vicorp.com/~skusep/ron/NEW36.jpg

I've also seen a UK car with the sensor handle, so maybe this were an option on European models. If you look at the door handle pull flap, there is a hole about 3 mm high x 10 mm long (estimate) above the key hole. The sensor is behind that hole. The control unit for the infra red locking is located next to the driver's seat belt reel.