(a) Two red lights one above the other:
No entry, lock out of service;
(b) A single red light or two red lights side-by-side:
No entry, lock closed;
(c) Extinction of one of the two red lights side-by-side or one red light and one green light side-by-side or a red light above a green light:
No entry, lock being prepared for opening;
(d) A single green light or two green lights side-by-side:
2. Exit from a lock shall be regulated both by day and by night by the following signal lights:
(a) One or two red lights: No exit;
(b) One or two green lights: Exit permitted.
3. The red light or lights referred to in paragraphs 1 and 2 above may be replaced by a board bearing the sign A.1 (annex 7).
The green light or lights referred to in the same paragraphs may be replaced by a board bearing the sign E.1 (annex 7).
4. In the absence of lights and boards, it is prohibited to enter or leave locks except by express order of the lock staff.
5. The provisions of this article also apply to any other types of crossings such as ship lifts and inclined planes.