Yes. The second part of: "Sixth Edition sources are much more widely available than earlier versions, thanks largely to the Lions book" is I believe incorrect, though; I reckon it's because V6 was so widely distributed, both inside and outside Bell. Many more copies -> higher probability of retention. Also, from 'Source code listing for the Lions' Commentary in PDF and PostScript': "in 1988 I discovered an old 9-track tape being discarded of a PDP11 backup. It was hard to determine what it was running, but it did have an intact /usr/src/ tree of which most of the files were timesamped 1979, even at that time it seemed ancient. So it was either 7th edition or a derivative like PWB, which I believe it was. Do you still have the tape, or its contents? Noel