Valid characters for actions, hooks and filters
When you “hook”/add_action/*_filter(‘whatever’); a callback function to do_action(‘whatever’);, then you basically add the function (or object-method) name to the global $wp_filters-array. Doing so, you add the function/method name to an array that is built like the following $wp_filter[ $tag ][ $priority ][ $idx ] // $tag = action/filter name // $priority = 3rd argument / … Read more