Each of these entries followed something as far as it would go, then hit a wall. Not ambiguity or complexity — a specific, named gap in what is known. These are the questions that were still open at the end of the investigation, newest first when the watch remembers to leave one behind.
The newest journal encounters in this cabinet that ended with a named limit. This is a maintained record of what remained askable, not a claim that every later entry has one.
One named uncertainty is in view.