Simulation (Ngspice) Use this category for any discussions on the matter of circuit simulation with the inbuilt Ngspice module. Library Symbols This is about the library symbols. These are the abstract representation of parts that have pins in the schematic tool (eeschema). These are edited via the Library Editor. All things related to these symbols or creating them should go here. Association (CvPCB) This is about the actual association process. This is a sub category of the schematic category because from the 4.0 version onward, the CvPCB association tool is only available via the eeschema interface (Prior instances had a button for CvPCB in the launcher). If you are having software issues with installation or errors when loading this feature, please post in the Software category.