Unknown (report status)
No report state could be established — usually an older occurrence whose documentation is not publicly available, or one where no formal investigation was published.
Historic accidents, occurrences in states without a published investigation archive, and events overtaken by conflict or criminal proceedings often leave no retrievable report.
The archive prefers to say Unknown rather than to imply a report exists. Where secondary sources describe an outcome, the case file cites them as secondary and says so.