 Warrant Officers in the United States forces are a special case as they are single track career specialists between the enlisted and officer ranks in terms of seniority, and have no NATO rank code.The system should not be confused with the pay grades used in the US military.While countries outside the NATO command structure do not strictly fall into this classification structure and there may be incidences of overlap (particularly in OR ranks between countries), the codes still provide a useful gauge in determining what ranks are broadly equivalent.