I had a tread dedicated to the "malicious bug". The thread has been zapped by unknown, if not by myself then by PTC. This thread explained for the XXXX times the "malicious bug" c/w the diagram, it does upset PTC : fine ! Since my flaming report and the removal of same report, the bug is still there and worse ... I had no problem opening and working on the Newton [today] because it had transited. The LL "RowEchelon Example_Handwork.mcd" has been saved 11 but didn't transit, therefore does not open . I was specifically recomforted to the effect that PTC is working hard to make sure that 14, 15 would be made available saved as lower versions, but today it does not at this very moment. So, I was told a lie ... my proof has been destroyed, but the bug not removed.
jmG