XXX was the marketing idea of ONE man who ran an ad with the slogan “too much sex for just one X”.
There is no “triple-X” rating.
Right, that’s what I tried (but apparently failed) to indicate. Because the MPAA failed to trademark X (an odd mistake because they TMed their other ratings) the smut industry got to use XXX as marketing. Which angered the MPAA but once you let that kind of cat out of the bag there’s no putting it back.