Hey, this came up a while ago and I cannot for my life find the answer. I feel a bit slow, but when I search for it I get a description but not the term.
There is an engineering method that prevents things from being plugged in wrong. One example is the old 3 1/2 floppy disk, it had a cutout so the disk wouldn't seat any way except the right way. They used to use a term for that kind of engineering, it was not quite jargon but more "jargon slang". Does anyone know what that term was?