The United States Navy

Commissioned officers can generally be divided into line officers and staff corps; line officers can be further split into unrestricted and restricted communities. Unrestricted Line Officers are the warfighting command element and are authorized to command ships, aviation squadrons, and special operations units. Restricted Line Officers, on the other hand, concentrate on non-combat related fields, such as engineering and maintenance; they are not qualified to command combat units. Staff Corps officers are specialists in fields that are themselves professional careers and not exclusive to the military, for example: medicine, science, law, and civil engineering.
• Chief Warrant Officer
Chief Warrant Officer (CWO) pay grades range from W-2 to the highest rank of W-5. United States Navy CWOs are officers whose role is to provide leadership and skills for the most difficult and demanding operations in a particular technical specialty. They occupy a niche that is not as well served by the line officer community, who tend to have a broader focus. CWOs come from the senior non-commissioned officer ranks of the enlisted and receive their commission after completing the Chief Warrant Officer Program. They typically become CWOs in specialties that are most related to their previous enlisted rating. Like Staff Corps officers, CWOs wear special insignia above the rank devices on their shoulder boards and sleeves to indicate their field of expertise.