In IALA Region A, what do red and green lateral marks depend on?

Lateral marks name the port and starboard sides of a channel in its conventional direction of buoyage. That direction is charted or set by the competent authority; it is not created by the boat's heading and cannot safely be assumed from a harbour or river mnemonic. Apply this before deciding how Region A red and green marks should appear, and revise Region A Lateral Marks and Direction.