The International Code of Signals is the alphabet of the sea — twenty-six letter flags plus numeral pennants, each a geometric arrangement of blocks, stripes, saltires and borders built from exactly five colors: red, yellow, blue, black and white. Those five were not chosen for beauty but for legibility: they hold their difference against open water, glare and grey sky at distance. Printed as a reference grid on a navy chart card, the flags become a study in functional contrast — flat color fields, crisp edges, no decoration that does not carry meaning.