Ochsenbein, F., Taylor, M., Donaldson, T., Williams, R., Davenhall, C., Demleitner, M., Durand, D., Fernique, P., Giaretta, D., Hanisch, R., McGlynn, T., Szalay, A. & Wicenec, A., 1 Oct 2019, International Virtual Observatory Alliance (IVOA), (IVOA Recommendation 21 October 2019).