Overview
ISO 2145:1978 - Documentation: Numbering of divisions and subdivisions in written documents - defines a simple, language-independent system for numbering sections, subsections and lower-level divisions in manuscripts, printed works, books, journal articles, instructions for use and standards. The standard promotes the use of Arabic numerals and dot-separated numbering to clarify sequence, hierarchy and interrelations of parts, to simplify search and retrieval, to enable precise citation of parts, and to facilitate internal cross-references.
Key Topics
- Scope and purpose
- Applies to all kinds of written documents (manuscripts, printed works, books, journal articles, instructions, standards).
- Numbering is advised when it clarifies order, importance and relations of parts, and when it simplifies retrieval and citation.
- Numbering format
- Use Arabic numerals for all division numbers.
- Main (first-level) divisions are numbered continuously starting at 1.
- Subdivisions at any subsequent level are numbered continuously within their parent division.
- Separate level numbers with a point (dot) (e.g., 1.1, 2.1.2, 1.3.1.21).
- Do not add a trailing point after the final number.
- Special cases
- A digit 0 (zero) may be assigned to an introductory part (preface, introduction) at any level.
- The system can be extended to many levels, but ISO 2145 recommends limiting the number of levels so numbers remain easy to read, find and cite.
- Citations and in-text use
- Division numbers are cited in text using the numeric form (e.g., “see 9.2” or “3rd paragraph of 1.1.2.2”).
- When spoken or enunciated, the dots are not pronounced (examples in the standard: 2.11 pronounced “two eleven”; 2.27 pronounced “two twenty-seven”).
Applications
- Authors, editors and publishers preparing structured documents, technical reports, academic books and standards.
- Technical writers, documentation managers and information architects seeking consistent document structure, easier navigation and reliable internal referencing.
- Libraries, archives and content management systems that index, cross-reference and automate retrieval of document sections.
- Useful for legal, regulatory and standards documents where precise citation of text fragments is required.
Related Standards
- ISO 2145 was developed by ISO/TC 46 (Documentation) and complements presentation guides such as the ISO guide for the presentation of international standards and technical reports. Use ISO 2145 together with organizational style guides and editorial rules to ensure consistent numbering and citation across publications.
Keywords: ISO 2145, numbering of divisions, document numbering, sections and subsections, document structure, table of contents, citation, documentation standards.