Mill a 50x30 pocket 5 mm deep. G00 X0 Y0 moves rapid to start. M03 S2000 starts spindle at 2000 RPM. G01 Z-5 F100 feeds down. G01 X50 F300 cuts the edge. Continue around, then G00 Z10 retracts and M05 stops. CAM software generates thousands of such lines from the CAD model.