<link rel="meta" type="application/rdf+xml" href="/labels.rdf#label1" title="Label for this page" />
A link tag to a specific label would look like this.
But does this move us on from PICS? We can do this now - "just ask production staff to include the right label."
It works in some situations and is a method of working we need to support but it doesn't solve the logistical problems of many large organisations.