Gary, your statement: "Vs 5 will open 5, 4, 3, 2 ,1" is not correct.
Before PAF 5 can handle earlier versions, they have to be converted.
Files from PAF 2.0 to 2.31, can either be converted into PAF 3 or PAF 4 files and the resulting file can then be converted to v.5, or,you can create a GEDCOM file from those earlier versions and import it into PAF 5.
Files from PAF 3.0 and 4.0 must be converted in PAF 5 before they can be used. During the file conversion process, you can save the converted file in a different folder and give it a different name. You can still use the original file in PAF 3.0 or 4.0.
The reason PAF 5 has to convert the files from previous versions is because of its ability to handle non-Roman characters means it is constructed in a different manner.