While software developers for desktop applications can rely on mouse and keyboard as standard input devices, developers of virtual reality (VR) and augmented reality (AR) applications usually have to deal with a large variety of individual interaction devices. Existing device abstraction layers provide a solution to this problem, but are usually limited to a specific set or type of input devices. In this paper we introduce DEVAL – an approach to a device abstraction layer for VR and AR applications. DEVAL is based on a device hierarchy that is not limited to input devices, but naturally extends to output devices.