H3 stands for "hybrid hereditary hysteretic". This is a term introduced by the owner of this web site, S. A. Belbas, to describe systems that contain at least one of the 3 ingredients: hybrid dynamics and/or control actions, hereditary properties (various forms of plain memory), and hysteresis (memory with selectivity and remanence).
Link to researchgate : https://www.researchgate.net/profile/S_Belbas