Here it comes, I hope it makes just a little sense:
[
www.fanfiction.net]
replace_metadata:
rating=>M=>Adults Only
rating=>T=>Teen
rating=>K\+=>Older Kids
rating=>K=>Kids
[
www.bloodshedverse.com]
replace_metadata:
rating=>R=>Mature
rating=>NC-17=>Adults Only
rating=>PG13=>Teen
rating=>PG=>Older Kids
[archiveofourown.org]
replace_metadata:
rating=>Explicit=>Adults Only
rating=>Mature=>Mature
rating=>Teen and Up Audience=>Teen
rating=>General Audiences=>Kids
[dark-solace.org]
replace_metadata:
rating=>Adults Only=>Adults Only
rating=>NC\17=>Adults Only
rating=>R=>Mature
rating=>PG13=>Teen
rating=>PG=>Older Kids
rating=>G=>Kids
[
www.nocturnal-light.net]
replace_metadata:
rating=>R=>Mature
rating=>NC-17=>Adults Only
rating=>PG13=>Teen
rating=>PG=>Older Kids
rating=>G=>Kids
[
www.spikeluver.com]
replace_metadata:
rating=>AO-AdultsOnly=>Adults Only
rating=>NC-17=>Mature
rating=>15=>Teen
rating=>PG=>Older Kids
rating=>18=>Mature
rating=>U=>Not Rated