Trust is the most valuable currency in machining. A programmer must trust that their code will not crash the machine. Powermill Pro 10 featured a highly accurate stock model simulation engine. This allowed users to visualize the material being removed block by block. It provided a "ViewMill" interface where users could see exactly what the finished part would look like, identifying any "rest material" (unmachined areas) or gouges before a single line of G-code was sent to the machine.