Hi Ima ;-) Currently the ActiveX interface for building systems is not documented. If you are interested in the ActiveX interface there are a couple of places that you can look to try to get you started. You can simply launch the VABIDE and add references to the Aecb items then use the object browser to get a general "idea" of the object model and where everything fits together. You can also take a look at the Panel Schedule application (both the AutoCAD and Excel versions) for some additional information. - jason
