Let's say I saw a question about "I am interested in adding in my universe" and I recall "X" being used in some existing universe. I want to answer something along the lines of "In the Space Hike universe X was included in this and that way and it obeyed the following rules" or "In the Ruler of the Bracelets X worked but was based on Y". So, in general describe how the same (or similar) element works in an existing body of fiction.
What would be a good way of making sure the answer is good and on-topic?