Manual:$wgXhtmlNamespaces

Output: $wgXhtmlNamespaces
Permit other XHTML namespaces in addition to the w3.org default.
Introduced in version:1.9.0 (r18943)
Removed in version:still in use
Allowed values:(array)
Default value:[]

DetailsEdit

Permit other namespaces in addition to the w3.org default.

Use the prefix for the key and the namespace for the value. For example:

$wgXhtmlNamespaces['svg'] = 'http://www.w3.org/2000/svg';

Normally we wouldn't have to define this in the root ‎<html> element, but IE needs it there in some circumstances.