How many categories are there at each level?

NACE Rev. 2.1, as adopted, has 22 sections, 87 divisions, 287 groups and 651 classes. The counts come from Table 5 in the Eurostat manual, which presents the changes in numerical terms between NACE Rev. 2 and NACE Rev. 2.1. The table gives 21 sections, 88 divisions, 272 groups and 615 classes for NACE Rev. 2, and 22 sections, 87 divisions, 287 groups and 651 classes for NACE Rev. 2.1, with differences of plus 1, minus 1, plus 15, and plus 36. The counts describe categories in the classification. They do not count businesses, activities, or statistical units.

How are the counts derived?

The manual explains the derivation in the passage beside Table 5. The increase in the number of sections is caused by the split of the former Section J into two sections, and is presented in the first row of the table. The smaller number of divisions results from the suppression of the former division 45, and is shown in the second row. The differences in the numbers of groups and classes result from the net difference between the number of new categories created in NACE Rev. 2.1 and the number of categories from NACE Rev. 2 that have been removed. The counts are therefore net counts: new categories minus removed categories, at each level, after splits, mergers, restructurings and renamings have been accounted for.

That net character matters for reading the counts. An increase of 36 classes does not mean that 36 new classes were created and none were removed. It means that the number created, minus the number removed, is 36. The manual section on major changes lists creations, splits, mergers and restructurings at class level, and the correspondence table gives the detailed relationship for each class. A reader who needs the gross numbers, meaning how many classes were created and how many were removed, must derive them from the correspondence table and the list of major changes, rather than from Table 5 alone. Table 5 gives the net result, not the gross movements.

Level	NACE Rev. 2	NACE Rev. 2.1	Difference
Sections	21	22	Plus 1
Divisions	88	87	Minus 1
Groups	272	287	Plus 15
Classes	615	651	Plus 36

Why do the counts differ between sources that round or summarise?

Counts differ between summaries when a summary counts a different thing, or counts at a different date. The manual table is the source for the adopted counts in this guide, because it is the table in the introductory guidelines that presents the numerical changes between the two versions. The EUR-Lex summary states the four level structure without giving the counts, and the Eurostat overview page states that new concepts were introduced at all levels without giving a count. A source that gives a different count must therefore be checked for what it counted: whether it counted the European structure or a national version with a fifth digit, whether it counted the structure as adopted or as published in a draft, and whether it counted residual categories separately or together with specific categories.

National versions illustrate the first difference. A national version usually adds a fifth digit, according to the manual, and the count of national categories below class level will be larger than the European class count. That larger count is a count of national detail, not a different European count. A reader who compares a national count with the European count without stating the level counted will appear to find a discrepancy where there is only a difference in level. The level and the version must be stated beside every count, and the source for the count must be named.

What do the counts not show?

The counts do not show how detailed the classification is for a particular field. A section with many classes is more finely divided than a section with few classes, but the number of classes in a section is not stated in Table 5, which gives totals only. A reader who needs the count for one section must count the classes listed for that section in the detailed structure in the manual, and must state that the count was derived by counting the structure table. The counts also do not show how many classes changed, because a class can be renamed, recoded, or partly changed without changing the total count. The correspondence table types give that detail: 354 classes with a one to one correspondence, 25 classes merged, 11 classes split, and 225 classes in a many to many correspondence, according to the manual passage on correspondence types. Those figures, which sum to the 615 classes of NACE Rev. 2, show the scale of change far better than the net count alone.

The counts also do not show the number of activities in the economy. A class can cover many activities, and the explanatory notes for a class can list many included activities. The count of classes is a count of headings in a classification, designed to balance disaggregation against workload in statistical offices, as the manual states. It is not a census of economic life, and it must not be presented as one.

Where are the counts confirmed?

The counts are confirmed in Table 5 of the Eurostat manual, in the introductory guidelines, in the passage that explains each row of the table. The section split that explains the first row is confirmed in Table 4 of the same manual, which compares the sections of the two versions. The correspondence type figures that explain the scale of change behind the net counts are confirmed in the passage on correspondence tables in the manual. For the meaning of any single category counted in those totals, the explanatory note for that category is the source, and for an entry, the institute or register that holds the record is the source.

Check Table 5 for the totals, check the correspondence passage for the scale of change, and confirm any entry with the national statistical institute or the business register that holds the record.