The first time, we have found a stamp in such a perforated style – doubtlessly very beautiful! What was part of a painful process with a library book perforating device some decades ago, can be done with an electric document perforater in a much more automatic and easier way today. The Openbare Bibliotheek Amsterdam used such a perforater to indicate when a book was part of the reading room (Open. Leeszaal) of their library.
To be sure, on the backside of the page, a rectangular stamp with the address of the reading room is added. The well visible lines make it nearly impossible to overlook the address. Probably, the library has more than one reading room and didn’t want to lose its books. To be mentioned is here also the book signature on a sticker in the right upper corner and the other codes in the middle of the page, which could mean that the book was part of different classifications.