WordPress at a glance
action is not described

update_option action-hook . WP 2.9.0

Fires immediately before an option value is updated.

Usage

add_action( 'update_option', 'action_function_name_6185', 10, 3 );
function action_function_name_6185( $option, $old_value, $value ){
	// action...
}
$option(string)
Name of the option to update.
$old_value(mixed)
The old option value.
$value(mixed)
The new option value.

Where the hook is called

update_option()
wp-includes/option.php 359
do_action( 'update_option', $option, $old_value, $value );

Where the hook is used (in WP core)

Does not used.