A useful thing for programmers and other users of mathematical symbols is searching for special characters on search engines. E.g. searching for the meaning of
$~ in Perl, or named mathematical sets like the positive reals
R+, or formatting
# in LaTeX.
It's useful enough that people have asked about it. A programmer asked on Stack Overflow: How can I use a search engine to search for special characters?
... someone else asked as a superuser / power user question: How to Google a question mark?
It has also been asked in Web Applications (closed as off-topic): How to search the internet for terms with special characters
And earlier (Google-specific, still open): How can I search for a keyword with special characters in Google Search?
Three of the four were closed as off-topic, in ways that were non-obvious to me. Google and other search engines don't have a clear FAQ in many cases; a single up to date explanation on what's possible seems useful. I've been using Google for nearly two decades now and I don't know a reliable way.
This is in meta as I would like to understand the shared community conventions that are resulting in what seems like a precise question falling between communities.