Unknown (report status)
No report state could be established. This is 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.