Traditionally for large apps or games, Android users had to download the main app/game from Android and then open the app and complete the rest of download. This would often result in the expiry of Market refund time and if you didn’t want that specific game or app, you were struck with it. But now, refund period won’t start until all the app files are downloaded.
On most newer devices, when users download your app from Android Market, the expansion files will be downloaded automatically, while on older devices, your app will download the expansion files the first time it runs, via a downloader library which we’ve provided below.
Developers can learn more about expansion files and other details at the Android Developers Blog.
