ABS develops and verifies conformance with standards for design, construction and operational maintenance of marine-related facilities. These standards are known as Rules and Guides. They are derived from principles of naval architecture, marine engineering and related disciplines. Currently, ABS has close to 100 Rules and Guides available. Rule Development Process With the exception of the principal Rules for Building and Classing Steel Vessels, ABS Rules and Guides are updated as deemed necessary to incorporate new requirements The principal Steel Vessel Rules are updated annually and are available to the industry in the first quarter of each calendar year. Rule Change Notices (RCN) may be issued from time to time, identifying changes in the technical content of the existing printed Rule. RCNs may be downloaded free of charge from the ABS website. Corrigenda to any published Rule or Guide may be issued at any time to address errors in the printed version. Corrigenda are posted to the ABS website for download periodically.