maybe...

as far as i know, the 'p' is for preset, you cannot overwrite it. 'u' for user you can write over it.
it means you can set up your fx sequences and settings, using the original settings as a starting point. once you get things where it all sounds good you can save it in the 'u' section and give it a name using the pads as a keyboard.
you've got the original os, vers2 has abc & d banks.
lots of extra fx and a vocoder.