18.  The International Morse Code is the General Service Code and is prescribed for use by the Army of the United States and between the Army and the Navy of the United States.  It will be used on radio systems, submarine cables using siphon recorders, and with the heliograph, flash-lantern, and all visual signaling apparatus using the wigwag.

         Alphabet.

A  . —         N  — . 
B  — . . .      O  — — —
C  — . — .      P  . — — . 
D  — . .        Q  — — . —
E  .            R  . — . 
F  . . — .      S  . . . 
G  — — .        T  —
H  . . . .      U  . . —
I  . .          V  . . . —
J  . — — —     W  . — —
K  — . —       X  — . . —
L  . — . .      Y  — . — —
M  — —         Z  — — . .

         Numerals.

1 . — — — — 6 — . . . . 2 . . — — — 7 — — . . . 3 . . . — — 8 — — — . . 4 . . . . — 9 — — — — . 5 . . . . . 0 - - - - -

Punctuation.

Period                                        . .   . .  . . 
Comma                                          . — . — . —
Interrogation                                  . . — — . . 
Hyphen or dash                                 — . . . . —
Parentheses (before and after the words)       — . — — . —
Quotation mark (beginning and ending)          . — . . — . 
Exclamation                                    — — . . — —
Apostrophe                                     . — — — — . 
Semicolon                                      — . — . — . 
Colon                                          — — — . . . 
Bar indicating fraction                        — . . — . 
Underline (before and after the word or
words it is wished to underline)             . . — — . —
Double dash (between preamble and address,
between address and body of message,
between body of message and signature,
and immediately before a fraction)           — . . . —
Cross                                          . — . — .

Visual Signaling in General.

21.  Methods of visual signaling are divided as follows: 

(a) By flag, torch, hand lantern, or beam of searchlight (without shutter). (General Service Code).

(b) By heliograph, flash lantern, or searchlight (with shutter).  (General Service Code).

(c) By Ardois. (General Service Code).

(d) By hand flags or by stationary semaphore. (Two-arm semaphore Code.)

(e) By preconcerted signals with Coston lights, rockets, bombs, Very pistols, small arms, guns, etc.

(f) By flag signals by permanent hoists. (International Code.)

22.  The following conventional signals, with exceptions noted, will be used in the first four classes.

Exceptions
Ardois and semaphore. 
End of word.  Interval. 
End of sentence.  Double interval. 
End of message.  Triple interval. 
Signal separating
preamble from
address; address
from text; text