It was very, very difficult to come up with the "Standard" label.
What do you call stuff that's not entirely worksafe or ok to show to your grandmother (or not ok to show her in public), but isn't as mature or complex as Harlequin romance novels or Steven King books? What do you call the rating for shows like ER?
Most sites label it "Teen" or "PG." But... that implies it wants teenage readers. Teen-suitable isn't the same as teen-oriented, and I had a really hard time trying to figure out how to label the difference.