Most user interfaces and ubiquitous systems are built around event-based paradigms. Previous work has argued that interfaces, especially those heavily depending on context or continuous data from sensors, should also give attention to status phenomena – that is continuously available signals and state. Focusing on both status and event phenomena has advantages in terms of adequacy of description and efficiency of execution. This paper describes a collection of XML-based specification notations (called XSED) for describing, implementing and optimising systems that take account of this dual status–event nature of the real world. These notations cover individual components, system configuration, and separated temporal annotations. Our work also presents a implementation to generate Status-Event Components that can run in a stand-alone test environment. They can also be wrapped into a Java Bean to interoperate with other software infrastructure, particularly the ECT platform.