WordPress generating invalid markup, How to remove it?
These two rel values are not invalid. The validator is not up to date.
tagis defined in the HTML5 spec.categoryis registered officially.
So it's no problem to use these values. The validator will probably catch up in the future.
Just paste the following code in your functions.php file inside your theme folder
function remove_category_rel($output){ $output = str_replace(' rel="category tag"', '', $output); return $output;}add_filter('the_category', 'remove_category_rel');