Final answer:
A service star or similar device is worn in lieu of receiving a sixth campaign or service medal, symbolizing multiple awards represented by a single ribbon.
Step-by-step explanation:
When a person is awarded a sixth campaign or service medal, traditionally a service star or similar device is worn on the ribbon of the campaign or service medal's ribbon in lieu of receiving another medal. This practice allows for the recognition of multiple awards or campaigns represented by a single ribbon. For example, Colonel Elizabeth Smellie's medal set includes significant awards like the Royal Red Cross Class 2 and the Canadian Centennial Medal, each symbolizing her numerous achievements without the need for a separate ribbon for each recognition.