The page glues the hotel label to the guest trunks to create a communication system with the next hotel page.
Indeed, depending on the position of the label, it means, e.g. at the top left, "low or generous or demanding customer care..."
It was very clever to invent this secret method !
Find the trunks and their history: https://www.la-malle-en-coin.com/en/general-history1/general-history.html