​AT&T Unix naming get's weird as they hire marketing people that don't quite get it.

V6 -> PWB [1.0 ~77] ---|

   |                           |

   +  UNIX/TS[~79] --      +​ PWB 2.0 [~79]  ----- PWB 3.0[~80]  <-- internal name of release

The "UNIX Support Group" - aka Summit - is supposed to be creating UNIX flavors for the different labs and operating companies and Research is to go back to doing research.  Thus PWB 3.0 is supposed to start to be a "superset" of the features added by the different labs, Columbus, IH, etc...   But it took a few spins before all the different hacks, additions were agreed too and added.   There was much fighting inside of BTL as we see outside.

IIRC an unreleased version of PWB 4.0 had the Columbus features in it as Horton points out.

Note that AT&T Marketing renames PWB 3.0 -- System III thinking that "Programmer's Workbench" would be a bad name to sell against IBM, and this it the first non-research system for License outside of the the labs.  If you look at the documentation set, et al - it all says PWB 3.0 on the cover and throughout   Also, the BSD vs AT&T wars basically start around this time....

Roll the clock forward and here is an new problem the PWB 4.0 moniker was used internally,  but AT&T marketing want to get rid of the PWB term - so the decree comes down the next release is to be called System V.

Certainly by this point, the Columbus changes had been folded into the main line kernel in Summit by then.   But as I said, my memory is what made it into SystemV and what was in CB-UNIX were similar but a little different.

Clem