Admiralty Nautical Charts and Publications should be maintained so that they are fully up-to-date for the latest safety-critical navigational information. The Admiralty Notices to Mariners (NMs) service provides all of the data you need to maintain Admiralty nautical products.
Admiralty NMs contain all the corrections, alterations and amendments for the UKHO's worldwide series of Admiralty Charts and Publications. They are published weekly in several formats but best known as the weekly booklets.