The first thing that happens within the script format.linux.refresh.4.pl (or an equivalent script for other partitions) is that the fourth partition on the hard drive is checked to see if it is an already existing Linux partition. If it is then the nothing is done to it at this stage. Otherwise a Linux partition is created on the fourth partition. Then the third partition is activated as a swap partition. This is all assuming that the third and fourth partition have already been created.