This site contains brief examples of an approach to evaluating usability of devices in context. The approach is ontological, because it is based on the relationship between the user's concepts and the concepts embodied in the device; and it is sketchy, because no more detail is included than is absolutely necessary. Hence the name, abbreviated to OSM. The authors are Ann Blandford and Thomas Green.
The site contains:
Historical note: the material on this site uses version 2 of OSM.