All it takes is a few of the biggest LLs/TGPs announcing a new rule requiring ICRA/meta tags -- the rest will follow suit.
After skimming a few PICS docs, I'm not sure which part is so complicated.
((PICS-version 1.1)
(rating-system "http://www.link-o-rama.com/child-idiot-safe/")
(rating-service "http://adultrating.link-o-rama.com/")
(name "Greenguy's Rating Service")
(description "Running a professional business means we go the distance to protect kids from being accidentally exposed to porn. Copyright 2006. All Rights Reserved.")
(category (transmit-as "h") (name "Hardcore Rating")
(label
(name "Gentle kissing and caressing")
(value 0))
(label
(name "french kissing, nipple sucking, rubbing pussy")
(value 1))
(label
(name "Face slapping, choking, ass fingering")
(value 2))
(label
(name "repeated facial cumshots while fucking a roomful of strangers")
(value 3))
(label
(name "Cleo's avatar")
(value 10))
What am I missing?