add extens point object handl posit object extens point handl us handl extend illeg argument except extens point extens point illeg argument except runnabl run runnabl run handl us us handl extens point add posit extens point extens point handl extend extend handl extens locat add posit extens point extens point model impl edit domain command stack execut chang command model impl run add extens point extens point handl 