 STEP-NC was designed to replace ISO 6983/RS274D G-codes with a modern, associative communications protocol that connects computer numerical controlled (CNC) process data to a product description of the part being machined.A STEP-NC program can use the full range of geometric constructs from the STEP standard to communicate device-independent toolpaths to the CNC.It can provide CAM operational descriptions and STEP CAD geometry to the CNC so workpieces, stock, fixtures and cutting tool shapes can be visualized and analyzed in the context of the toolpaths.