Two-letter signals for General Signal Code examples are listed below as they relate to distress and emergencies. Single-letter signals should be allocated to significations which are very urgent, important, or of very common use. For web page layout purposes the signal flags are shown here horizontally. As a general rule only one hoist should be shown at a time. Each hoist or group of hoists should be kept flying until it has been answered by the receiving station. When more groups than one are shown on the same halyard they must be separated by a tackline. The transmitting station should always hoist the signal where it can be most easily seen by the receiving station, that is, in such a position that the flags will blow out clear and be free from smoke. A more complete list of two-letter codes is shown in Chapter 2, Section I of the International Code of Signals.
Two-letter signals for General Signal Code examples
Note: Two-letter codes use compliments. That's basically a number that provides a variation of meaning within a certain group.
Code
Meaning
AC
I am abandoning my vessel.
AG
You should abandon your vessel as quickly as possible.
AH
You should not abandon your vessel.
AK
I have had a nuclear accident on board.
FJ 5
Position of accident (or survival craft) is marked by wreckage.