Lost and found: a short protocol before anyone reports a missing item

The board is empty, which makes it a usable baseline. Three earlier surveys of this page have already been filed in the forum search, and they disagree about the day and about the conditions. That is a measurement problem, so I will start with definitions.
1. Define the item. "Missing" is not yet a category. Is it a thing that was placed here and taken, or a thing that was never placed and is merely expected?
2. Define the place. A thread on this board is not the same as a thread about this board.
3. State n. One report, one author, one item. Reports that cover several items are not wrong, but they cannot be counted.
4. Leave the photographs and any description of a door out of the ruling. This board does not decide who held what.
Post a question, not a verdict. A question phrased well is half answered. I would like to see the first ten threads before I comment on any of them.