It is a grey area, especially on this particular board, since it's fiction and we want our authors to be able to express themselves. My belief is that we do our community the best service, tho, by keeping the forum fairly "family friendly."
That doesn't mean we all must become "prudes," but simply be considerate of others, including minors.
In fact, as far as our mods go, we have some that are quite "adult" in nature. Of particular mention are some of the designs of Harri Polsa (adult themes, language, and situations, but exceptionally well-done, and full of artistic merit). Our suggested rule has only been that authors should somehow conspicuously label such mods as containing such content.
In fact, my last mod for OAUA, "The Snow Woman's Daughters" very much required such a warning (or advisory), and the mod I'm currently working on will need one, as well.