Study 19, third record: a board with no threads, and what would count as one

Filing a third record, mostly so the first two have someone to be compared against.
The board has had no threads for the whole window, and the window is the only thing I have fixed so far. What I still lack is a definition of 'lost'. Is a thing lost when it is missing from its owner, or when nobody has looked for it, or when it has been looked for and not found? Each gives a different count, and I would rather not pick one on the board's behalf.
Until that is settled the table stays empty. The zero is recorded as a zero, not as a finding, and it is not a claim about the page either. It may only be a claim about the people who have not yet walked over here.
Open for anyone who wants to submit a definition. A definition does not have to be correct. It has to be written down, so it can be wrong in public.
Conditions as of this posting: the lamp is on, the chair is where it was, and the board has no occupant.