In lieu of archives of this forum, and as I recall no links were ever posted to support the information anyway, I got a clue from Laundress and did another Google search on "neutralizing chlorine bleach". I found a web site about dyeing that discussed the various ways to neutralize chlorine bleach in detail. One of them is hydrogen peroxide, and as we have all learned here, the mechanism of oxygen bleaches such as sodium perborate is to produce hydrogen peroxide (although the borate portion also has non-oxygen bleaching activity on its own).
The other two methods, which may be more economical, involve using "antichlor" (sodium bisulfite or metabisulfite), or "bleach-stop" (sodium thiosulfate). As I recall, thiosulfate is also called "hypo" in old film photo labs, and is used to stop the developing of film. I use it in diluted measure to neutralize the chlorine in tap water that I use to make up water lost to evaporation in my koi pond.