It is assumed that erotic & porn games (that should be tagged with porn) have nudity, so this tag is redundant in those cases. Please note that nudity in and of itself does not automatically equate to porn by many people's definition. Also, note that nudity in and of itself does equate to porn by many people's definition. Most legal definitions say it is porn if "If it is intended for sexual stimulation".
About Nudity
There's really no need (at this point in UVL history) to tag games with this if they already have a properly placed 'standard' rating for it.
Except these standard ratings can't be used to filter results based on this aspect (to include only games with it or to exclude games with it).
note that nudity in and of itself does equate to porn by many people's definition
Not in Europe, AFAIK. And even outside of this place it's probably only seen as indecent, not pornographic.
I think the description needs to be updated, or at least references to other rating systems removed as there's no purpose for them at all.
Edit: Removed a large chunk of the text that pertained only to usage in relation to other rating systems, which is irrelevant for the concept itself.
Edit: Removed a large chunk of the text that pertained only to usage in relation to other rating systems, which is irrelevant for the concept itself.