WordPress at a glance
filter is not described

login_form_top filter-hook . WP 3.0.0

Filters content to display at the top of the login form.

The filter evaluates just following the opening form tag element.

Usage

add_filter( 'login_form_top', 'filter_function_name_3420', 10, 2 );
function filter_function_name_3420( $content, $args ){
	// filter...

	return $content;
}
$content(string)
Content to display.
Default: ''
$args(array)
Array of login form arguments.

Where the hook is called

wp_login_form()
wp-includes/general-template.php 431
$login_form_top = apply_filters( 'login_form_top', '', $args );

Where the hook is used (in WP core)

Does not used.