33 CFR 62.52: Automatic Identification System Aids to Navigation (AIS AtoN).

(a) Aids to Navigation (AtoN) may be enhanced by the use of an automatic identification system (AIS). AIS is a maritime navigation safety communications protocol standardized by the International Telecommunication Union and adopted by the International Maritime Organization for the broadcast or exchange of navigation information between vessels, aircraft, and shore stations. AIS AtoN can autonomously and at fixed intervals broadcast the name, position, dimensions, type, characteristics and status from or concerning an aid to navigation.

(b) AIS AtoN can be either physical (fitted to the AtoN), synthetic (physically fitted somewhere other than to the AtoN) or virtual (physically nonexistent, but capable of being portrayed on AIS-capable displays).

(c) AIS AtoN can also be used to broadcast both laterally (e.g., Port Hand Mark) and non-laterally significant marine safety information (e.g., environmental data, tidal information, and navigation warnings).