I believe there is an addon file for Cythera (Points to User Data essential). It is a blank file,save for its formatting as a Cythera document. Numerous programs can open it partway--but it usually can't define it...Except for Photoshop. If you open it as raw data in Photoshop it becomes a black-and-white binary bitmap.I suppose you could use photoshop as an editor if you knew what code to change and how to convert it back to a cythera file.