用来描述一个特定的嵌入式项目中的某一软件模块。应用软件不象可重用的交叉嵌入式平台，只是因为每一个嵌入式系统有不同的应用软件。

• Describes software modules specific to a particular embedded project. The application software is unlikely to be reusable across embedded platforms, simply because each embedded system has a different application.