Use MAKEDEF.EXE to create a definition file listing all exported symbols from a DLL. The definition file is used by LIB.EXE to create an import library. MAKEDEF accepts a single DLL file including the .dll extension as a command line argument, and creates a file with the same name having the .def extension. If a definition file with this name already exists, it is overwritten. MAKEDEF ignores all exported symbols that contain three or more sequential underscore characters. The MAKEDEF utility requires that DUMPBIN.EXE be available in a directory on the path. See Creating import libraries for instructions on generating an import library.