International Territorial Level

International Territorial Level (ITL) is a geocode standard for referencing the subdivisions of the United Kingdom for statistical purposes, used by the Office for National Statistics (ONS). From 2003 and until 2020 it functioned as part of the European Union and European Statistical System's geocode standard Nomenclature of Territorial Units for Statistics or NUTS. Following Brexit, the ONS set to develop a domestic statistical classification framework separate from NUTS. Currently, the ITLs are a mirror to the pre-existing NUTS system, they retain the same three level hierarchy and boundaries used for NUTS in the United Kingdom since 2018, with the next review scheduled for 2024.

Source: Wikipedia — International Territorial Level (CC BY-SA 4.0)