Most of the time, the parameter files are specific to each program, and highly dependent on the features of that program. Theoretically, any fractal program with both a formula parser and the ability to control color values directly can render the same fractals as any other program, as long as the necessary formulas are available. In practice, this turns out to be very complex. Ultra Fractal, for example, can import many FractInt fractals--but not all of them, because it doesn't do everything that FractInt does. Going the other way, I've managed to render an Ultra Fractal image in FractInt, but to do so I had to write a true color simulator into the FractInt formula, and the formula was specific to the multi-layered image I was rendering. Chaos Pro can open many UF parameter and formula files, too, but this required careful programming on the part of its author. So while it is possible, it's not often done, because it's very complicated and far from perfect. For the fractal artist working with their own images, wanting to import them into new software and tweak them further, these are useful tools. For people wishing to share images, they're less useful, because unless you send an image too, you can never be sure the parameters are being interpreted correctly!