“…So far, most of the research effort has focused on identifying and specifying PSMs. As a result, several PSM libraries are now available Breuker et al, 1987;Benjamins, 1993;Puppe, 1993;O'Hara, 1995;Breuker and van de Velde, 1994;Motta, 1997) and a number of PSM specification languages have been proposed, ranging from informal notations (Benjamins, 1993;Schreiber at al., 1994) to formal modeling languages (Fensel and van Harmelen, 1994). The latter area of research is now well established, to such an extent that two projects, one in Europe, IBROW 3 (Benjamins et al, 1998), and one in the US, High Performance Knowledge Bases (HPKB, 1997), have been set up with the aim (among other ones) of producing standard formalisms for PSM specification.…”