WordPress at a glance
filter is not described

respond_link filter-hook . WP 4.4.0

Filters the respond link when a post has no comments.

Usage

add_filter( 'respond_link', 'filter_function_name_6346', 10, 2 );
function filter_function_name_6346( $respond_link, $id ){
	// filter...

	return $respond_link;
}
$respond_link(string)
The default response link.
$id(int)
The post ID.

Where the hook is called

comments_popup_link()
respond_link
wp-includes/comment-template.php 1548
echo apply_filters( 'respond_link', $respond_link, $id );

Where the hook is used (in WP core)

Does not used.