1. The terms “white light”, “red light”, “green light”, “yellow light” and “blue light” mean lights of colours according to the provisions referred to in Annex 4 to these regulations;
2. The terms “strong light”, “bright light” and “ordinary light” mean lights of intensities according to the provisions referred to in Annex 5 to these regulations;
3. The terms “scintillating light” and “quick scintillating light” mean rhythmic lights flashing 40-60 times per minute and 100-120 times per minute;
4. The term “short blast” means a blast lasting approximately one second, and the term “long blast” means a blast lasting approximately four seconds, the interval between two consecutive blasts being about one second;
5. The term “series of very short blasts” means a series of at least six blasts lasting approximately ¼ second each, separated by intervals of approximately ¼ second;
6. The term “three-tone signal” means a signal repeated three times, of three blasts of different pitch with no interval between them lasting about two seconds in all. The frequency of the blasts shall be within the range 165 to 297 Hertz and the difference between the highest and the lowest blasts shall be at least two full notes. Each series of three blasts shall begin with the lowest and end with the highest note.
7. The term “peal of a bell” means two strokes of a bell.