PTA: Fourth Order Administrative Unit

PTA (Alpine Technology Platform) project: Administrative units where jurisdictional rights are exercised for local, regional and national government.
(From INSPIRE D2.8.I.4 - Data Specification on Administrative units)
Each administrative unit is characterised by the territory within its competence; that territory consists of main areas and particular areas representing either administrative islands or areas of territorial waters or portions of inland waters (parts of lakes).