Subject matter is a controlled vocabulary that shows the concepts used for the indexation of notices published on EUR-Lex. It has been extended to show the concepts that provide the legal framework of the European Central Bank and the Protocol on Ireland/Northern Ireland. The newest extension is Themes in focus. Subject matter is part of the Core Metadata used in the exchange between the institutions involved in the legal decision making process and the Publications Office of the European Union. It is under governance of the Interinstitutional Metadata and Formats Committee (IMFC), maintained by the Publications Office of the European Union and disseminated on the EU Vocabularies website. The subject matter classification exists in parallel with two other classifications: the Directory of European Union Legislation and EuroVoc. Differently from these, the subject matter classification is strictly aligned with the evolution of the European Union policies cited in the different treaties of the European Union that can be consulted at: http://eur-lex.europa.eu/collection/eu-law/treaties.html?locale=en