yearranges

A yearrange is a representation of a period defined by a starting year and an ending year. It is used to denote spans of time in historical records, bibliographic data, and event timelines. In many data contexts a yearrange succinctly conveys when something occurred or was applicable.

Notation commonly uses an en dash to connect the years, for example 1999–2005. In some contexts a hyphen is used or phrases such as from 1999 to 2005. By default, year ranges are treated as inclusive, meaning both the start and end years are part of the range. Some representations indicate ongoing status with a term such as present or with a placeholder to indicate an open-ended range.

In data modeling, a yearrange is usually stored as two integers: start_year and end_year. For open-ended ranges end_year may be null or marked as present. When calculating duration, inclusive counting is used; duration equals end_year minus start_year plus one. When BCE/BCE and CE/CE designations are involved, additional metadata or astronomical year numbering may be required.

Common challenges include inconsistent notations, ambiguous inclusivity, and handling partial overlaps or gaps between ranges. Best practices include standardizing the notation within a project, explicitly stating whether endpoints are inclusive, and documenting any calendar system or era used. Yearranges provide a compact way to represent periods across various domains such as history, publishing, and version control.

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