A new user asked a question about what a mechanism in a picture was. I'm sure we have had such questions before, and I think we have generally allowed them, but a recent one attracted several "unclear what you are asking" down votes.
Many other sites have an identification tag †, so I have created one for this kind of question, even though it would probably be considered a meta tag, which are now explicitly discouraged.
I think it would be useful to agree whether, as a community, we want identification questions, or whether we consider them off-topic.
† Feel free to tag (or suggest a tag on) any questions you find, it might help us understand how common this kind of question is.