The Black ribbon This Shinobi Represents, are used as general symbols for mourning, and you may see magnetic versions raising awareness for POW/MIA as an alternative to yellow. This color is used as a sign of mourning, but also represents melanoma awareness, sleep disorders, and gang prevention. Other neutral colors are discussed below: Black: Amish Support, Primary Biliary Cirrhosis, Gang Prevention, Accidents, Gun Control, Anti-Terrorism, Narcolepsy, Mourning, POW/MIA, Sleep Apnea, Sleep Disorders, Students for Gun Control, Melanoma, Trauma