It wouldn't be impossible or even difficult to reverse engineer the format. All you would have to do would be generate the output for each input. Since there are a small number (relatively) of inputs, it would be tedious but not difficult. Why would anyone want to keep the file format of a user interface secret? The more people or programs which use the interface, the more useful the interface becomes. If I create a program which can take logical input and generate an xml file which in turn can generate a brains file more people can use Mach3 easily. If I have a 12 key input device and don't want to delineate every possible sequence in the brains editor, I can create an xml file which in turn can create a brains file.