SEMSYN [ParkerParker1999] is a Graphplan-based planner, with extensions to handle metric and ADL features. In general, Graphplan-based approaches have, with the exception of LPG, proven unequal to the challenge of scaling to meet the latest sets of benchmark problems. This suggests that the search strategy of Graphplan must be abandoned if large problems are to be solved, but that the underlying plan graph structure need not be a source of scaling problems (in fact FF, VHPOP, SAPA and LPG all use plan graph structures in the planning process).