Elevator

We have recently moved into a new building, The Susquehanna Commerce Center. We are on the 3rd floor of the building and I usually take the elevator. Well yesterday I wanted to see how far I could open the elevator door while it was moving. Well apparently the answer is as far as you want. However, the elevator comes to a complete stop once you open the door I would say 18 inches. I know this because I opened the dorr pretty far yesterdya and the elevator stopped. I let go of the doors, they shut and the elevator started moving again. I must admit I was worried that either the elevator wouldn't start back up, or an alarm would go off, luckily neither of those things happened. Just an FYI......