Kilo Flag
F5. The Reference Layer: Glossary, Units, Signals and Information SourcesDefinition
International Code of Signals letter K, meaning "I wish to communicate with you."
Kilo is letter K of the International Code of Signals and means “I wish to communicate with you.” The flag is split vertically, yellow at the hoist and blue at the fly. Hoisted singly it invites another vessel or a shore station to open communication, by light, flag, radio, or other means. As Morse code, the letter K is also the recognized signal inviting a station to transmit.
Source: International Code of Signals (IMO, 1965 edition as amended), single-letter signal K.