So the other day I was trying to return a book to one of the many closet-sized University libraries scattered around Vienna. The library had closed before I got there at 2:00 or something equivalently ridiculously early and I was trying to determine whether the slot in the door was just for mail, or also a book drop. I deliberated for a long time and even called one of my Austrian friends, who from my description was also unsure. Fortunately I was talking long enough and loud enough (it is great being American isn't it?) while holding open slot flap (I have no idea what the right word for that thing is) that one of the employees came from the back and let me give back my book. Tangentially, if it wasn't her somebody had definitely been smoking pot there. Anyway, she was very nice and it turned out the slot really was just for mail. She called the slot a Babyklappe, which sounded innocent enough at the time, you know baby slot whatever, the things are low, you know like babies built them for babies or something. Then I spoke to my friend Eva. She told me a Babyklappe is a hatch/box that mothers can put their babies in after birth if they want to give it up. Apparently these things are pretty common and started Middle Ages. Just thought you should know, though I don't think they should use the same word for any kind of slot, that could end badly.