Final answer:
A 'DUI' stands for Distinctive Unit Insignia, which is a metal heraldic device worn on military uniforms by soldiers in the United States Army to symbolize their unit's identity.
Step-by-step explanation:
When speaking of uniforms and insignia, a "DUI" refers to a Distinctive Unit Insignia. This is a metal heraldic device worn by soldiers in the United States Army. The DUI is unique to each unit and serves as a visual symbol representing the unit's history, mission, and values. These insignias are worn on a soldier's uniform and are designed to foster unit pride and esprit de corps. The design of a DUI often includes elements such as mottoes, colors, symbols, and shapes that are significant to the unit's identity. They are typically approved by the Institute of Heraldry and can be found on a soldier's beret, service cap, or over the right breast pocket on the dress uniform.