Significato freccia in php/oscommerce

[ratlook]

guarda, visto che sei così gentile, ne approfitto per chiederti se puoi spiegarmi questo codice che davvero non riesco a capire... grazie!

$products_image = new upload('products_image');
$products_image->set_destination(DIR_FS_CATALOG_IMAGES);
if ($products_image->parse() && $products_image->save()) {
$products_image_name = $products_image->filename;
} else {
$products_image_name = (isset($HTTP_POST_VARS['products_previous_image']) ? $HTTP_POST_VARS['products_previous_image'] : '');
}