Exactly what does that pertain to?
Something within Firefox, or a website, or other?

It's FireFox, when I set options for receving posts from the support site (like whether or not I want to receive a digest or individual e-mails). This particular aption is supposedly set be responding to the question "Which topic categories would you like to subscribe to?"

I also see a system-defined answer: "No topics defined". And there is no drop-down list or text box, so so no visible wat to set up some topics.

So - How do I define a topic or list of topics?