What is the term for those cylindrical metal or plastic protrusions that are inserted into mounting holes to mount a thing onto another thing? At first I thought of tab, but to me that makes it sound like it's flat, not cylindrical. Is there a proper term, or is it tab after all?
So far I've tried
protrusion, projection, lug, tab, knob, and nub
but none of these seem to be right.
This picture is not exactly what I had in mind, but it is close. Instead of a "rotated T" shape, picture a regular cylinder used to mount or align things to be mounted. I knew about dowels, but I thought that word could only be used when the pieces were separate like in Andrew's first two pictures. Are they still called dowels when they are one with the object being mounted?