Kansas Nebraska Overprints Of 1929 With Missing Period

So the question is not that broken die created missing periods can be found on other denominations but that missing periods could be found on other denominations created from inking issues as the link discussed. And are these considered by Scott's as true missing periods?

"true missing periods" risks being on fringe of interesting among "error, freak or oddity" (EFO) items. Since overprints like precancels don't have the same rigorous characteristics or security concerns as the stamp design itself. That's why vast majority of variations therein are relegated to specialists' studies. Scott has their hands full as it is with "errors", consistent, persistent and explainable variations that would be considered at least "interesting" by the general collector.
Note an error can 'start' in mid-print run, due to a mechanical change like ink runs out, something nicks print plate, etc... as long as stamps "before" don't show it and "all" (in run) afterwards do show it. Otherwise something that is less persistent or constant is 'only' a freak or oddity. Sometimes if an efo is interesting enough, it will get mention as a catalog footnote.
One will note a few 'constant plate varieties' (CPV) listed without catalog # in the older "classic" stamp series... and these were due to the engraved plates, much more than overprinting. they are sometimes listed (without Scott #) and sometimes have a market value, yet many many more are not listed; they are less dramatic visually and found by "flyspecking" specialists who enjoy that as part of their hobby. Scott does not try to be that level of documenting for all collectors.

I collect and sell these print varieties. The market is very good for these unlisted items. I enjoy the search!

Been away for awhile and just run across this thread. Made me take out my U.S. album and look at my Kansas Nebraska overprints. My 3¢ Lincoln Nebraska overprint sc#672 has no period and no indention. It really makes no different to me but good information here, thank you