Manual:$wgEnforceHtmlIds

Parser: $wgEnforceHtmlIds
Allow id's that don't conform to HTML4 backward compatibility requirements.
Introduced in version:1.14.0 (r45171)
Removed in version:1.16.0
Allowed values:(boolean)
Default value:true

Details edit

Allow id's that don't conform to HTML4 backward compatibility requirements.

This is currently for testing. If all goes well, this option will be removed and the functionality will be enabled universally.

This was renamed to $wgExperimentalHtmlIds in r61691 (1.16) and converted to use laxer HTML 5 syntax.