Gap 10: a file counts the library instances it places, creates, pastes or duplicates and reports them like its detaches. The server counts what a file's totals grow past their highest in the current week and keeps a year of weeks (actions.json). library.usage {days} and Show usage give insertions and detachments over the past 30 days, 90 days or year. New variants are appended; an older server refuses them and Show usage says so.