USer Interface eXtensible Markup Language (UsiXML) consists of a User Interface

Description Language (UIDL) allowing designers to specify a user interface at multiple levels of abstraction depending on the development path they are following: task and concepts, abstract user interface, concrete user interface, and final user interface. These levels support to some extent independence with respect to device, computing platform, modality of interaction, channel of information, and context of use. A single user interface can be specified and produced at and from different, possibly multiple, levels of abstraction while maintaining the mappings between these levels if required. Thus, the development process can be initiated from any level of abstraction and proceed towards obtaining one or many final user interfaces for various contexts of use (forward engineering), by recovering the final user interface into any upper level (reverse engineering), or by adapting at any level of abstraction (reengineering).