XSL Extensible Style Language, CSS Cascading Style Sheets
RDF Resource Description Framework; language for writing metadata
Example:
<RDF xmlns:DC="http://purl.org/DC">
<Description about="http://www.w3.org/folio.html">
<DC:Title>The W3C Folio 1999</DC:Title>
<DC:Creator>W3C Communications Team</DC:Creator>
<DC:Date>1999-03-10</DC:Date>
<DC:Subject>Web development, World Wide Web
Consortium, Interoperability of the Web</DC:Subject>
</Description>
</RDF>
PICS Platform for Internet Content Selection; standard for annotating (rating) webpages according to their content; based on RDF
Example:
<META http-equiv="PICS-Label" content='
(PICS-1.1 "http://www.w3c.org/PICS/vocab.html"
labels for "http://w3.org/PICS/vocab.html"
exp "2000.09.04T08:15-0500"
ratings (q2 v3))'>