What do [i]you[/i] use the 18+ tag for?

When seeing that tag, what do you think it means?

Personally, when I mention 18+, I don't mean a smut-fest of an RP. I mean that there is potential for darker themes, adult situations*, and [i]potential[/i] (not guaranteed) 'romance' scenes. I also use it to filterer out under-18 individuals, because I'm not comfortable playing in a 1x1 RP with someone under the age of 18.

Others, however, do use the 18+ tag for plots that are more explicitly 'romantic' in nature.

Should there be two separate tags? Or should both uses fall under the same tag? 

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*damn taxes.