Name Tags on Doors Requirements?

I’m looking into this and cannot figure out of this is a CFR requirement or what the deal is. Can anybody suggest where to look, I’m not finding anything online about it.

Always had to have name tags on crew doors on the cruise ships I worked on. Maybe it’s an IMO thing.

Actually on the doors, or on the door frame above, i.e. “Stateroom, Two (2) Seamen”? I believe that it is a tonnage admeasurement requirement. Not sure under which scheme. I have carried out IMO (and class) Passenger Ship Surveys and don’t recall having to verify any name tags on doors.

And then there is the equally important question, particularly on passenger ships: where is that person actually sleeping?