hmm.. i have these while i was in the states... back in 1996.
basically, it's an accessory that lets u open your door via a remote, regardless you have door handle or not. Most people installed this in anticipation of shaving off the door handle.
The thing is pretty basic. just like auto lock and unlocking, there's an additional solenoid which trigger a motor that opens the door. There's a stopper installed with it, so that the door won't swing open all the way, rather just popped out a bit, like popping up your front hood.
I had it on my Civic EF before and shaved the door handle. Definitely makes the car look nicer and cleaner.
oh, the on-board release button just releases one door. so, it's either the driver side or passenger side. I had it wired to the boot of the car and disguised the button as one of the controls on my preamp. :D hehehe.