WordPress at a glance
action is not described

custom_header_options action-hook . WP 3.1.0

Fires just before the submit button in the custom header options form.

Usage

add_action( 'custom_header_options', 'action_function_name_5075' );
function action_function_name_5075(){
	// action...
}

Where the hook is called

Custom_Image_Header::step_1()
custom_header_options
wp-admin/custom-header.php 703
do_action( 'custom_header_options' );

Where the hook is used (in WP core)

Does not used.