Classification levels

A statistical classification has a structure which is composed of one or several classification levels. A classification level is often characterised by a generic name for the classification items that it regroups. For instance, the NACE uses the terms "sections", "divisions", "groups" and "classes"; the Combined Nomenclature (CN) has sections, chapters, headings, HS subheadings and CN subheadings; the NUTS includes 4 levels: Level 0 (Country), level 1 (NUTS 1), level 2 (NUTS 2) and level 3 (NUTS 3). The bottom level is always the most detailed level i.e., has the most precise information (detailed values) for the variable classifying the statistical unit. Classification levels is maintained by Eurostat and published by the Publications Office of the European Union on the EU Vocabularies website.统计分类具有由一个或多个分类层级构成的结构。每个分类层级通常以其所归集的分类项的通用名称来标识。例如，欧洲行业分类（NACE）采用了"部门"、"分部"、"组别"与"类目"四类术语；联合命名法（Combined Nomenclature，CN）则包含部门、章、目、协调制度子目（HS subheadings）以及联合命名法子目；区域统计单元命名系统（NUTS）设有四级层级：0级（国家层级）、1级（NUTS 1）、2级（NUTS 2）与3级（NUTS 3）。最底层层级始终为最详细的层级，即可为统计单元的分类变量提供最为精准的信息（细化数值）。该分类层级体系由欧盟统计局（Eurostat）维护，并由欧盟出版物办公室（Publications Office of the European Union）在欧盟词汇表（EU Vocabularies）网站发布。