Hi Tim,

Good hearing from you, when did you leave Sandia?

It's been about a year.

On the observer question, entities that are not intersected will persist, including the RefEntity's, though whether something isn't modified depends on what the engine does (it's keyed off whether the underlying engine changes its topological entity). With Cubit, we've had mostly expected results that way, so no big worries.

Any idea about the OCC backend? I ask because the attached program calls webcut on one of the example models (62_shaver1.brep) and faces to both sides of the cut sheet (as well as one that intersects the sheet) all report GEOMETRY_TOPOLOGY_MODIFIED. The notify_observer() method called on observers doesn't appear to provide information about the entity(-ies) replacing those being modified. Is there a way to obtain the resulting split or merged entities? If I create an attribute to hold an ID on faces or edges of interest, how fast will lookup be? Thanks, David