How is a many to one row read?

A many to one row is read from the old side to the new side first, and then back again. From Rev. 2 to Rev. 2.1, several old classes point to one new class. From Rev. 2.1 back to Rev. 2, one new class draws on several old classes. Both directions are needed. The forward direction shows consolidation. The reverse direction shows the mixed origin of the new heading. A reader who reads only one direction will miss half of what the row says, and may treat a combined heading as if it had a single origin.

The row is a statement about categories. It is not a statement about any individual business, and it never picks a new class for a specific entry.

What does the forward reading show?

The forward reading answers a narrow question: where do the activities in each old heading go? In a many to one pattern, the answer is the same new heading for each old heading in the group. That sameness is the whole point of the pattern. It tells a dataset user that series compiled under the old headings must be combined to compare with series compiled under the new heading. It also tells a dataset user that the new heading is broader than any one of its sources. The breadth matters for interpretation. A rise in the new heading can come from any of its sources, and the table alone cannot say which source drove the change. The explanatory note for the new class, with its inclusions and exclusions, states the combined scope.

Reading direction	Question answered	Limit
Rev. 2 to Rev. 2.1	Where do old activities go?	Shows the destination, not the share from each source
Rev. 2.1 to Rev. 2	Where did new activities come from?	Shows the origins, not the share each origin contributes
Either direction alone	One half of the link	Misses the mixed origin or the consolidation

The table above is a reading guide for row shapes. It lists no specific codes, because the method is the same for every many to one row, and the specific rows must be read in the published correspondence table for the headings concerned.

What does the reverse reading add?

The reverse reading prevents a common error: treating the new heading as the continuation of one favourite old heading. Where several old headings feed a new one, none of them continues alone. Each contributes part of the new scope. A time series that follows only one old heading into the new heading will understate the new scope and overstate continuity. Eurostat and its partners prepare backcasting plans so that historical series can be presented under the new version, and the correspondence table is the starting point for that work. Backcasting uses methods and source data beyond the table itself. The table shows which headings combine. It does not show the proportions in which they combine, and it does not replace the backcast series when one is published.

How is the combined scope checked?

The combined scope is checked in the explanatory note for the new class. The note lists what the class includes and what it excludes, and it cross refers to neighbouring classes where an activity sits close to a boundary. A reader should read the note for the new class in full, then read the notes for the old classes that feed into it, and note what was added, what was dropped, and what was already shared. If an activity appears in the inclusions of the new note but in the exclusions of one old note, the correspondence row and the notes together explain the movement. If an activity appears in neither note, the reader has not yet found the right heading, and should widen the search to neighbouring groups and divisions before concluding anything.

What must never be read into a many to one row?

A many to one row must never be read as a guarantee that every unit in an old heading belongs in the new heading, and it must never be read as a decision about a specific business. Where a table says many to one, the mapping is a category link, not a 1:1 guarantee. Confirmation for a specific business comes from the national statistical institute or the business register holding its record. A code does not decide tax, social security, licensing, funding or collective agreement matters. The row shows the structure of the classification. The institute or register shows the entry. Keeping those two apart is what makes the row useful rather than misleading.

Read the row forward to find the destination, read it back to see the mixed origin, and let the explanatory note state the combined scope before any entry is confirmed.