International code flags are used to signal between two ships or between ship and shore. Also called signaling flags, they are a set of flags of different colors, shapes and markings which used singly or in combination have different meanings. The flags include 26 square flags which depict the letters of the alphabet, ten numeral pendants, one answering pendant, and three substituters or repeaters

A Diver down, keep well clear		B Discharging or carrying heavy goods		C Yes (Affirmative)		D Keep clear, manoeuvering with difficulty		E Altering my course to starboard
F I am disabled, communicate		G I require a pilot/I am hauling nets		H Pilot on board		I Altering my course to port		J On fire, dangerous cargo keep well clear
K Communicate with me		L Stop your vessel instantly		M My vessel is stopped, no way on		N No (negative)		O Man overboard
P (at sea)nets fast on obstruction/ (in port) crew return to vessel		Q I request free practique		R No single letter meaning		S My engines going astern		T Keep clear, pair trawling
U You are running into danger		V I require assistance		W I require medical assistance		X Stop and await my signals		Y I am dragging my anchor
Z I require a tug

Numeric pennants

1		2		3		4
5		6		7		8
9		0		CODE Answering Pennant or Decimal Point
1st Substitute		2nd Substitute		3rd Substitute