Well, but the issue is, I haven't got the foggiest idea what to google for in order to get it to cough up information on self-locking doors. (No permutation of "self-locking" seems to do it.) Because, yeah, there are a bunch of different mechanisms, and the closest I've been able to get to actually any sort of solid information is to look up push-button locks. Come to think of it, the "push in and turn to lock" type doorknobs that I remember are mostly from older houses I've lived in, and mostly on bathrooms.