One or both of these files may be requested by manufacturers to save them having to generate the files themselves.
The IPC-D-356 Netlist file is an ASCII text file that includes instructions for the CAM software such as net names, pin, and XY locations of start and end points for each net or node. The manufacturer uses this file to create test fixtures to verify the produced PCBs, this is especially important in high-volume applications.
The Pick and Place file, also called a centroid file, records the spatial position of all surface-mounted devices (SMDs) on the circuit board. The position data includes layer, XY location, and rotation.
As an alternative to the Pick and Place tool, the user language program (ULP) mountsmd generates files for SMD locations on both top and bottom layers (if applicable).