This function adds encoded copyright information to the MIDI file. In cases that somebody illegally removes or changes the standard visible copyright field, the secret copyright information remains in the file hidden. The secret copyright can prove your copyright when somebody else tries to steal it.
If a secret copyright (done with GNMIDI) already exists then it displays the secret copyright information.
If no secret copyright found, but standard copyright is available then this copyright information is added as secret copyright into the file.
If no standard and no secret copyright found then program asks for a copyright line. Use only ASCII characters (characters blank - ~), other characters (like international characters e.g. ü) are not stored.