Real quick I just opened two versions of a bryce object in hexedit...a default sphere and a default sphere lifted and elongated along the y-axis only. There is a LOT of empty space in the file that seems like it could be cut down...I think this may be why bryce files compress so well. What I found was that there were a LOT of little differences in a lot of places, you'd really have to know hex to really get it I think. ANyhoo the most interesting part is at the end of the code. It has clearly marke hex lines for material properties, origin, position, scale, etc. But then what is the rest of the file used for?