How is an ISIC reference cited?

An ISIC reference is cited by naming five things: the classification, the revision, the category, the document consulted, and the check date. A citation that names only the code, such as a four digit string, cannot be repeated, because the same string can appear in more than one revision with a different meaning, and in more than one classification with a different meaning. A citation that names the five items can be opened by another reader, in the same document, and checked.

The discipline is the same as for a NACE citation, and it matters more for ISIC, because ISIC is the reference for international comparison, and a comparison built on an uncited code cannot be audited.

What is named first: the classification or the revision?

The classification is named first, and the revision second, because the revision only has meaning inside the classification. A citation should read, in effect: ISIC, Revision 5, category, in the document consulted. The United Nations Statistics Division classification detail for ISIC Rev. 5 lists the full name, International Standard Industrial Classification of All Economic Activities, Revision 5, its status as operational, its year adopted as 2024 (FIXED, as listed by the Division), and its custodian as the United Nations Statistics Division. A citation to Rev. 4 should name Rev. 4 in the same place, and should cite the Rev. 4 publication, not the Rev. 5 publication. A citation to a national classification derived from ISIC should name the national classification and its version first, and ISIC and its revision second, as the derivation, so that the reader can tell which classification the code belongs to and which it is derived from.

What document is cited?

The document cited is the publication consulted for the category: the structure file, the structure and explanatory notes file, or the introduction, as listed by the Division. The Division classification detail for ISIC Rev. 5 lists the available formats as PDF, Excel and CSV, and the available elements as the introduction, the structure, and the explanatory notes. The Division states on its ISIC page that the Rev. 5 publication is currently undergoing copyediting and preparation for publication, and that the final version will be provided when available. A citation made while the final publication is in preparation should therefore name the file consulted, whether that is the structure only file or the structure and explanatory notes file, and should give the date of the check, so that a later reader who opens the final publication can tell whether the category note has changed. A citation that names only the classification, without the document, leaves the reader to guess which file was used, and a guess is not a check.

How is the category named?

The category is named by its code and its title, at the level cited, with the note summarised where the note matters to the argument. A section is named by its letter and title. A division is named by its two digits and title. A group is named by its three digits and title. A class is named by its four digits and title. The note for the class, where it is cited, should be quoted or paraphrased with attribution to the Division publication, and the inclusions and exclusions that matter should be stated, not assumed. A category cited at class level should not be summarised by its section title, because the section title is a broader statement, and a reader who follows the citation to the section will not find the class note. The level of the citation should match the level of the argument, and where the argument is about a class, the citation should be at class level.

Citation item	Example form, with no category asserted
Classification	ISIC
Revision	Rev. 5, structure endorsed March 2023 (FIXED), notes endorsed March 2024 (FIXED)
Category	Code and title, at the level cited
Document	Structure file, or structure and explanatory notes file, as consulted
Check date	Date the document was consulted

The table is a citation template, and the category row is deliberately left without a named category, so that no category is asserted in this guide without a document consulted for it. The template should be filled from the document consulted, for the category in question, and the filled citation should be checked by opening the document again.

How is a comparison cited?

A comparison is cited by naming the correspondence used, the revisions on both sides, and the mapping type for the pair compared. Eurostat describes correspondence tables between two different classifications as tables that show the relationship between all positions of the two classifications involved, and the same discipline applies to an ISIC comparison. A comparison that states that two categories correspond, without naming the table, the revisions, and the mapping type, cannot be checked, and it should not be relied on. Where the mapping is one to many or a split, the comparison should be made at the aggregate, or the split should be described, with the note for each category cited. Where the mapping is one to one, the revisions should still be named, because a one to one mapping in one pair of revisions may not hold in the next pair.

What does a citation not decide?

A citation does not decide the code for any unit, and it does not decide tax, licensing, funding, collective agreement or social security questions. A citation is a record of a check, and its value is that another reader can repeat the check. The holder of the record, the national statistical institute or the business register, is where a specific business entry is confirmed. The meaning of an ISIC category is confirmed in the Division publication for the revision cited. A well formed citation makes both confirmations possible. A poorly formed citation makes neither possible.

Cite the classification, revision, category, document and check date together, and confirm a business entry with the institute or register that holds it. ”