WordPress at a glance
filter is not described

pre_comment_author_url filter-hook . WP 1.5.0

Filters the comment author's URL cookie before it is set.

When this filter hook is evaluated in wp_filter_comment(), the comment author's URL string is passed.

Usage

add_filter( 'pre_comment_author_url', 'filter_function_name_163' );
function filter_function_name_163( $author_url_cookie ){
	// filter...

	return $author_url_cookie;
}
$author_url_cookie(string)
The comment author URL cookie.

Where the hook is called

sanitize_comment_cookies()
wp_filter_comment()
wp-includes/comment.php 604
$comment_author_url = apply_filters( 'pre_comment_author_url', $_COOKIE['comment_author_url_' . COOKIEHASH] );
wp-includes/comment.php 1861
$commentdata['comment_author_url'] = apply_filters( 'pre_comment_author_url', $commentdata['comment_author_url'] );

Where the hook is used (in WP core)

Does not used.