os.Path.rename() is used to change a file or a directory name:
CALL os.Path.rename(old_name, new_name) RETURNING result
where
All the file names you use in your 4gl development must be platform-independent.
If you use platform-dependent names (e.g., combine upper and lower case, use colons, finish names with a full stop, etc.), please remember that they might cause different problems when you move your project to another platform.