Diver down flag. A diver down flag, or scuba flag, is a flag used on the water to indicate that there is a diver below. Two styles of flag are in use. Internationally, the code flag alfa/alpha, which is white and blue, is used to signal that the vessel has a diver down and other vessels should keep well clear at slow speed.
Familiarize yourself with some friendly network cables and take a closer look at common types of network media, including twisted-pair cable, coaxial cable, fiber-optic cable, and wireless.
I've played around with those, blue cables for data network, yellow for trunks between switches, firewalls and routers, green for media gateways and VoIP stuff. Cable color codes are eye candy, the're pretty but not worth the trouble : You now need to stock cables in different length and colors everywhere.