Nitrox is a mixture of oxygen and nitrogen, in fact you are breathing a mixture of nitrox right now. Enriched air nitrox (EANx) is an air mixture that contains greater than 21% oxygen. Diving with EANx allows divers to have more time underwater without the need for decompression.
The course will teach you the rules and limitations of diving with EANx. There is no set schedule for this course.