“Cancellation” is the term used when an ENC producer removes its own ENC from service(because of huge amount of updates) and issues a replacement cell as a new edition whereas “withdrawal” is the term used when UKHO decides to remove an ENC of a certain producer nation from service because of safety or technical issues. Information on withdrawn ENCs is published via weekly AVCS readme file. The withdrawn ENC numbers are kept published in the readme file until the producer nation has cancelled it. Vessels should delete these ENCS and record in NP133C.
About “cancelled” ENCs, there is no information in readme file or weekly Notice to mariners. Users should check on a weekly basis if they have any cancelled ENCs on the ECDIS.
They should download the list of “Replacement for cancelled ENCs” from UKHO website. This list contains ENCs that have been cancelled and their replacements. If cancelled cells are present on the ECDIS, user should ensure the ECDIS has replacement cells (to check from the list) and delete the cancelled ones. Users to check how the their ECDIS indicates/represents the cancelled ENCs.