Final answer:
The Combat Distinguishing Device is a "V" device signifying valorous actions or heroism in combat and is worn when authorized in the award citation.
Step-by-step explanation:
The Combat Distinguishing Device is an emblem that is affixed to certain United States military decorations to denote that the achievement or service was performed under combat conditions. It is typically recognized by a "V" device that may be attached to service medals and ribbons. This device may only be worn if it is specifically authorized in the award citation. The presence of this device indicates that the service member engaged in acts of heroism or valor during combat operations.