Since MediaWiki 1.16, the software has supported — as an option — RDFa and Microdata HTML semantic attributes.
This commit, integrated to the next release on MediaWiki, 1.27, will embrace more the semantic Web making these attributes always available.
If you wish to use it today, this is already available in our Git repository.
This also simplify slightly the cyclomatic complexity of our parser sanitizer code.
Microdata support will so be available on Wikipedia Thursday, 24 March 2016 and on other projects Thursday, 23 March 2016.
If you already use RDFa today on MediaWiki
First, we would be happy to get feedback, as we’re currently considering an update to RDFa 1.1 and we would like to know who is still in favour to keep RDFa 1.0.
Secondly, there is a small effort of configuration to do: open the source code of your wiki and look the <html> tag.
Copy the content of the version attribute: you should see something like like <html version=HTML+RDFa 1.0">.
Now, edit InitialiseSettings.php (or your wiki farm configuration) and set the $wgHtml5Version setting. For example here, this would be:
$wgHtml5Version="=HTML+RDFa 1.0";
For the microdata, there is nothing special to do.