Thanks for the question! This is loosely equivalent to exchanges with a smut minimum. It would apply to artworks as well, in which case a visual depiction of sex would be required in the image. Given posing and differences of opinion about nudity, I wouldn't necessarily require an Explicit vs. Mature rating or like, visible genitals, but sex will be required in the image. Thank you for drawing my attention to this - I'll make there are explicit instructions in the sign up post to refer to, for both fic and art.