Fog signal port
Alternative terms: Port, Slot
In some types of compressed air fog signal apparatus e.g. siren or diaphone, an aperture, generally narrow and elongated, on both the fixed and moving parts of the modulator of the compressed air.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
acceleration due to gravity (m/s2)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM