What are methods of signalling as per INTERCO or International Code of Signal ?

The methods of signaling which may be used are:

1. Flag signaling, the flags used being those shown inside the front cover.
2. Flashing light signaling, using the Morse symbols shown in Chapter 1.
3. Sound signaling, using the Morse symbols shown in Chapter 1.
4. Voice over a loud hailer.
5. Radiotelegraphy.
6. Radiotelephony.
7. Morse signaling by hand flags or arms.

Note :

Flag signaling

A set of signal flags consists of twenty-six alphabetical flags, ten numeral pennants, three substitutes, and the answering pennant. Detailed instructions for signaling by flags are given in Chapter 1,

The international flagbag consist of 40 flags: 26 alphabetical flags, 10 numeral pennants, 3 substitutes, and the ANSWER pennant.         

Flashing light and sound signaling.

The Morse symbols representing letters, numerals, etc., are expressed by dots and dashes which are signaled either singly or in combination. The dots and dashes and spaces between them should be made to bear the following ratio, one to another, as regards their duration: