[TUHS] UNIX v4 Source Code Commentary - complete book now available

[Phil Budne via TUHS]

General question: Is "v4" really the right thing to call the tape?

Page 1 footnote 1 reads

  UNIX Fourth Edition was released in November 1973. The source code
  in this book comes from a tape sent to the University of Utah in
  June 1974, containing the V4 distribution with minor updates. See
  Ken Thompson’s letter to Martin Newell dated May 31, 1974

While https://gunkies.org/wiki/UNIX_Fifth_Edition says v5 was dated June 1974.

I understand the temptation to be the "John Lions of v5" and to be the
first to plant a flag on heretofore unknown ground, but I'm more
interested in understanding the tape in full context (what differences
are seen between tape contents fall in relation to the extant v4 man
pages, and the known "v5" sources?).

I'd probably be more interested in short summaries of how the new tape
differs from the Fourth Edition documentation, the "v5" sources, and
finally v6, as documented by Lions.

phil

P.S.
I'm probably just as, or more guilty of misnomering, since I may have
helped propogate the term "version zero" for the recovered PDP-7 UNIX
code when I was helping to bring it up and annotate it.

P.P.S.
Then there is the worm can of whether "Version" anything exists
(the manual was published in editions, and tapes were made at various
time) especially in earlier times...