Containers on the iPad

Hello, As part of a summer internship project, I am trying to make a web app of sorts for the iPad. I want to of course take advantage of everything VO has to offer, but one thing that I've not come across before is containers. I believe they are iPad specific? For our purposes right now, that is fine. Is there a certain bit of code used to invoke them and have VO make the sound like you are going to the dock? Google is for once not being helpful, so I don't know if the word "container" is a VO term. This explanation would help a lot. Thanks!