A PSN or GCN Service that the PSNA asserts shall be provided once - by a limited number of providers at any point in time - in order to improve the efficiency of the PSN. Examples of PSN Central Services include root DNS and root PKI services
Public Services Network (PSN), PSN Glossary, version 1.2 PSN Document Management and Change Control - version 1.3, Prepared by PSN Core Team, London, UK 2011. https://www.gov.uk/government/uploads/system/uploa ds/attachment_data/file/136008/PSN-Glossary-v1-6.p df, (Public Srvc Network - Brit) {552}