Hi, I wonder if http://austingroupbugs.net/main_page.php would be a better place to discuss this because it could involve more people that have worked on POSIX's wording that just Jörg, and thus may either have a different opinion, or be able to phrase it in a more persuasive manner. It doesn't seem tar specific? Get the semantics hammered out, any clarifications to the `spec' agreed, and then GNU tar can either follow, or wilfully deviate, and document that.
-- Cheers, Ralph. https://plus.google.com/+RalphCorderoy