Last updated February 7, 2011. Created by NonProfit on April 22, 2010.
Edited by arianek, Tor Arne Thune, scor, laura s. Log in to edit this page.

RDFa (or Resource Description Framework – in – attributes) is a W3C Recommendation which allows embedding metadata within Web documents. Drupal 7 outputs RDFa data in core. The following changes are required to your theme to be valid RDFa:

  • The DOCTYPE must be changed to XHTML+RDFa 1.0.
  • The old lang attribute should be removed for compatibility with XHTML 1.1, only xml:lang should remain.
  • The RDF namespace prefixes used throughout the HTML document need to be serialized in the html tag and are contained in the $rdf_namespaces variable.
  • The GRDDL profile should be specified in the <head> tag.

Drupal 6.x (page.tpl.php)

In Drupal 6, you need to edit page.tpl.php and use this snippet:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN"
  "http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="<?php print $language->language; ?>" version="XHTML+RDFa 1.0" dir="<?php print $language->dir; ?>"
  xmlns:content="http://purl.org/rss/1.0/modules/content/"
  xmlns:dc="http://purl.org/dc/terms/"
  xmlns:foaf="http://xmlns.com/foaf/0.1/"
  xmlns:og="http://ogp.me/ns#"
  xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
  xmlns:sioc="http://rdfs.org/sioc/ns#"
  xmlns:sioct="http://rdfs.org/sioc/types#"
  xmlns:skos="http://www.w3.org/2004/02/skos/core#"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
>
  <head profile="http://www.w3.org/1999/xhtml/vocab">

You can add more namespace definitions depending on what vocabularies your site uses.

Drupal 7.x (html.tpl.php)

Drupal 7 is RDFa aware and will populate the $rdf_namespace and $grddl_profile variables which you can insert in html.tpl.php. Note that in most cases, you probably won't need to override the default html.tpl.php provided by the system module. In case you do, use this snippet:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN"
  "http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="<?php print $language->language ?>" dir="<?php print $language->dir ?>"
  <?php print $rdf_namespaces ?>>
  <head profile="<?php print $grddl_profile ?>">

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