DatumFlag is a comprehensive reference and training tool for the International Code of Signals (ICS). It covers all 40 signal flags — 26 letter flags, 10 numeral pennants, 3 substitutes, and the answering pennant — plus two-flag signal codes, semaphore positions, and Morse code. All data is bundled — no internet connection required.
Browse all 40 ICS flags organised by type: letter flags, numeral pennants, and special pennants. Each entry shows the flag, letter, phonetic name, Morse code, and single-flag meaning. Tap any flag for a detail view including an animated semaphore figure showing the correct arm positions.
Browse two-flag signal codes used in ship-to-ship and ship-to-shore communication. Filter by category: distress, navigation, manoeuvring, medical, meteorological, communications, and cargo. Search by code, meaning, or category.
Type a message and watch it transmitted letter by letter in flag semaphore. An animated signaller raises and lowers flags through the correct positions for each character. Transmitted letters appear as ICS flags beneath the figure. Adjust signalling speed from Cadet to Yeoman.
Eight quiz modes to test your knowledge: Flag to Meaning, Meaning to Flag, Flag to Letter, Letter to Flag, Phonetic to Flag, Morse to Letter, Signal to Meaning, and Semaphore to Letter. Choose session length (10, 20, or 40 questions, or Endless) and difficulty (Easy, Standard, or Hard). High scores are saved per mode.
Choose between green and amber display themes. Configure quiz question count and difficulty. Your preferences are saved between sessions.
For support queries, please open an issue on GitHub.