These are 5 position alpha-numeric codes comprising the d series. All other level II codes and descriptors are approved and maintained jointly by the alpha-numeric editorial panel (consisting of CMS, the Health Insurance Association of America, and the Blue Cross and Blue Shield Association).
Alaska: Although Alaska enjoys a high volume of aurora activity, its cruises are not often mentioned as northern lights cruises. During the Alaska cruise season, it's rarely dark enough for the lights to be visible.
For the Vikings the haunting appearance of the northern lights was an ethereal reflection of the ghosts of virgins. Many Inuit peoples interpreted the eerie sight as walrus spirits playing with human skulls. The Native American Tlingit of Alaska believed the strange sky visions were dancing spirits of the deceased.