What do section, division, group and class mean?

Section, division, group and class are the four levels of the NACE hierarchy, from the broadest to the most detailed. A section is identified by one letter. A division is identified by two digits, inside a section. A group is identified by three digits, inside a division. A class is identified by four digits, inside a group, and it is the most detailed level. Each lower category belongs to exactly one category above it, as the sample guide for this site states, and each level narrows the level above.

The four levels are the grammar of every NACE code, and a code cannot be read without naming the level it sits at.

What is a section?

A section is the broadest grouping in NACE, identified by one letter, such as J or K in NACE Rev. 2.1. The EUR-Lex summary lists the 22 sections of NACE Rev. 2.1, from agriculture, forestry and fishing through to activities of extraterritorial organisations and bodies. A section groups a broad area of activity, and it is used for broad comparisons and for publication at the highest level of aggregation. A section title is a general statement, and it should never be used as the meaning of a class inside it, because the class note narrows the section title considerably. A reader who cites a section should cite it as a section, with its letter and title, and should state that the citation is at section level, so that a later reader does not mistake it for a class citation.

What is a division?

A division is a narrower field inside a section, identified by two digits. NACE Rev. 2.1 has 87 divisions, as adopted. A division groups activities that share a broad field, such as a set of manufacturing activities inside the manufacturing section, or a set of service activities inside a service section. Divisions are coded consecutively, with gaps provided to allow additional divisions to be introduced without a complete change of coding, as Eurostat states in its NACE background article, for sections where a future need for additional divisions is deemed most likely. A division code on its own is a two digit statement, and it should be cited with its section letter where the section matters, and with its title, so that the division is placed in its section. A division total in a dataset is the sum of the groups and classes inside it, and it hides the movement inside it, where a class split or moved.

What is a group?

A group is a narrower field inside a division, identified by three digits. NACE Rev. 2.1 has 287 groups, as adopted. A group narrows the division further, and it is the level at which many datasets publish, where class level detail is not required or is not reliable. A group code is the first three digits of the class codes inside it, and every class in the group shares those three digits. A reader who cites a group should cite it at group level, with its three digits and title, and should not present it as a class, because the group contains more than one class, and the classes inside it can differ in their notes. A group is a useful level for comparison where the class detail differs between versions, because the group can stay comparable while its classes split, and the correspondence table should be checked to confirm that the group itself did not change.

What is a class?

A class is the most detailed level in NACE, identified by four digits, inside a group. NACE Rev. 2.1 has 651 classes, as adopted, which is 36 more than in NACE Rev. 2. A class is the level at which the explanatory note gives the detailed inclusions, exclusions and borderline cases, and it is the level at which a unit is coded in a business register, in the European classification. A class code should be cited with its four digits and its title, and with the note consulted, because the title alone does not give the boundary of the class. A class that split in the revision is shown in the correspondence table as a one to many mapping, which does not by itself pick the new class for a specific unit. A class that merged is shown in the reverse pattern. The class is the level where the checking discipline in this site is strictest, because it is the level where a wrong reading has the most direct effect on a comparison.

Level	Identifier	Count in NACE Rev. 2.1, as adopted	Use
Section	One letter	22	Broadest grouping, broad comparison
Division	Two digits	87	Narrower field inside a section
Group	Three digits	287	Narrower field inside a division
Class	Four digits	651	Most detailed level, register coding level

The table is a glossary in tabular form. It gives the identifier, the count, and the use for each level, in one place, so that a reader can place any code at its level without opening another guide. The counts are for NACE Rev. 2.1, as adopted, and they should not be used for another version, where the counts differ.

What does the hierarchy not decide?

The hierarchy does not decide the code for any unit, and it does not decide tax, licensing, funding, collective agreement or social security questions. It is a structure for grouping activities for statistics. The entry for a specific business is confirmed with the national statistical institute or the business register that holds the record, at the level the register uses. The meaning of a category at any level is confirmed in the Eurostat explanatory notes for that level, and the move between versions in the correspondence tables. The hierarchy is the frame. The note is the meaning. The register is the entry.

Name the level with every code, read the note for the class, and confirm a business entry with the institute or register that holds it.