Just some VCDIFF files for upgrading/downgrading between various IWAD releases without having to use DOS patchers (which are both slow and somewhat difficult to run). VCDIFF is a binary patch standard, probably most common with xdelta3, but any program that supports them would work.
An example for upgrading plutonia.wad to the id Anthology version:
$ cd plutonia.wad $ xdelta3 -d -s plutonia.wad 1.9-to-anthology.vcdiff plutonia-anth.wad