Final answer:
When wearing full-size medals on military dress uniforms, service and training ribbons are generally not worn together. Ribbon bars may be worn on less formal occasions where full medals would be impractical. Consult branch-specific regulations for precise guidelines.
Step-by-step explanation:
In military dress protocol, you generally do not wear service and training ribbons when wearing full-size medals. Full-size medals are typically worn on formal occasions and are displayed on the outer garment of a dress uniform. Ribbons may be worn on less formal occasions or when the wearing of full-size medals would be impractical. There can be exceptions to this based on specific branch regulations or for certain ceremonial occasions, so it is essential to consult the uniform regulations for the specific military branch in question.