Light is NOT basic. They are restrictive, yes, but they are not basic economy. However, DL does not sell light fares. Light fares are sold by other airlines. If you ticket a "light fare" on DL ticket stock somehow, then yes, you can treat it like Main Cabin. However, light fares ticketed on other airline stock will have some level of restriction and most foreign carriers do NOT have the same penalty-free change policies as the US carriers do.