These directories contain sources in Ratfor from the Kernighan and Plaugher book Software Tools as I implemented it on two platforms more years ago that I care to remember: Perkin-Elmer and VAX VMS. Ratfor is history as C is victorious as THE systems implementation language and weird machines with 28 bit words and that sort of thing are a thing of the past. I think even the Perkin-Elmer machines are history. So these sources are here for historical interest. If you are still using Ratfor, there is a nice diff (that doesn't come from K+P) that I translated from the Unix implementation.