TS 3139

TS 3139 is a standard concerned with how weeks are numbered, including how the first day of the week is defined and how week 1 of the year is established. It provides a basic framework for interpreting calendar dates consistently when week-based records, schedules, or database entries need to be aligned across systems.

What week numbering means in practice

In general technical use, week numbering expresses time within a year in calendar weeks rather than by individual dates. This is especially useful in planning, reporting, archiving, and software systems that organise information by week. Defining the first day of the week and the rule for week 1 is essential because the same date can otherwise fall into different week numbers depending on the convention used.

The common technical domain covered by this standard

The scope of this standard focuses on establishing the first day of the week and the identification of week 1. That makes it relevant to date display, software output, business records, and statistical documentation where week numbers must be used consistently. Such a definition helps normalise how week counts are handled around calendar-year boundaries.

This TS was published as equivalent to ISO 2015:1976 and was later withdrawn. Even so, the subject remains technically useful as a reference point for consistent week-based interpretation when date data move between systems.