The PDFsets.index file is a flat file, distributed with the tarball, containing a one line description of each available PDF set. In particular it gives the LHAPDF numeric code to use for each member in the set. The filename is given and the member number to use from that PDF set. In addition the old PDFLIB type, group and set numbers are given. For the newer sets which were not in PDFLIB the latter two numbers are set to zero.
It unpacks into the base level directory