I tried to find a capable and simple converter to help you solve this problem and could not find any, instead I realized that you mentioned that the software was used to create text files and then I tried to open a sample MSS file into a known and powerful text editor and it worked. Of course there is code formatting used by the original software but it is easily removable because it does not interfere with the original text and you can remove it with a few clicks. You use Notepad++ (which is free) to open and save your files to a standard text file format such as .txt, .rtf, etc.
