ISO 2015 is a standard superseded by ISO 8601.1 The ISO week numbering system was introduced in ISO 2015. It was issued as an international standard in 1976, technically identical to ISO Recommendation R 2015 from 1971.
^Technical Committee ISO/TC 154, Processes, data elements and documents in commerce, industry and administration. (2004-12-01). "ISO 8601:2004(E)". ISO. Retrieved 2006-11-15. Annex A … Identification of a particular date by means of ordinal dates (ISO 2711) and by means of the week numbering system (ISO 2015) were alternative methods that the basic concept of this International Standard could also encompass; thus, ISO 2015 and ISO 2711 have now been superseded.