Two-letter signals for General Signal Code examples are listed below as they relate to miscellaneous codes. 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 V 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
SU
What is your cargo?
SU 5
My cargo is livestock.
SZ
Total number of persons on board is…
GZ
All persons saved
GZ1
All persons lost
TO
I have a mine in my sweep (or net).
TV
Fishing in this area is prohibited.
TF4
I am shooting long lines.
TD
I am a fish catch carrier boat.
UL
All vessels should proceed to sea as soon as possible owing to danger in port.
Code
Meaning
UM
The harbor (or port indicated) is closed to traffic.
UO
You must not enter harbor.
UT
Where are you bound for?
UU
I am bound for…
UV 4
You are violating the conditions of innocent passage through the territorial sea (as indicated
in the table of complements below). Request you comply with the conditions of
innocent passage through the territorial sea.
UW
I wish you a pleasant voyage.
UX
No information available.
UY
I am carrying out exercises. Please keep clear of me.