WordPress at a glance
filter is not described

login_headertitle filter-hook . WP 2.1.0

Filters the title attribute of the header logo above login form.

Usage

add_filter( 'login_headertitle', 'filter_function_name_9782' );
function filter_function_name_9782( $login_header_title ){
	// filter...

	return $login_header_title;
}
$login_header_title(string)
Login header logo title attribute.

Where the hook is called

login_header()
login_headertitle
wp-login.php 137
$login_header_title = apply_filters( 'login_headertitle', $login_header_title );

Where the hook is used (in WP core)

Does not used.