NoteWorthy Composer supports the following file formats:
*.nwc - NoteWorthy Composer Native Format
The program saves files natively to files that use the *.nwc file extension. This is a proprietary file format used exclusively by NoteWorthy Composer and its support programs.
*.mid - MIDI Performance Files
The program can import *.mid files and convert the MIDI performance into standard NWC notation. MIDI files are imported using the File, Open command (in NWC2, you should use File, Import), or by simply dragging and dropping the files onto the NWC application window. You can create a MIDI file using File, Save As (in NWC2, you should use File, Export).
*.kar - Karaoke MIDI Files
These are just MIDI files with a different extension, and a slightly different format for embedding lyric text. NWC can import these files, but cannot save in this format.