When creating and building your application, it is important to choose the correct version of the BlackBerry JDE to make sure that the application is compatible with the target BlackBerry smartphones. Applications built in the BlackBerry JDE are forward-compatible with newer BlackBerry Device Software versions, but they are not backward-compatible with older versions.
For example, an application built in BlackBerry JDE 4.1 runs on a BlackBerry smartphones running BlackBerry® Device Software 4.1 and later. It does not run on a BlackBerry smartphones running BlackBerry Device Software 4.0. Thus, when building applications, you should use a BlackBerry JDE version that matches the lowest version of BlackBerry Device Software you want to support.
Note: To verify the version of BlackBerry Device Software installed on the BlackBerry smartphone, select Options > About.