I thank Sture Hägglund, Mark Musen, and Kristian Sandahl for valuable discussions about DOTS, and I am grateful to Lyn Dupré for editorial assistance. The examples based on the Sisyphus VT task benefited from discussions with John Gennari and Thomas Rothenfluh.
The preparation of this manuscript has been supported in part by grants LM05157 and LM05305 from the National Library of Medicine, by gifts from Digital Equipment Corporation, and by scholarships from the Swedish Institute, from the Fulbright Commission, and from Stanford University. The development of DOTS has been supported by the Swedish National Board for Industrial and Technical Development (NUTEK).