Editing Era (section)

===Regnal eras===
{{main|Regnal year}}
The word era also denotes the units used under a different, more arbitrary system where time is not represented as an endless continuum with a single reference year, but each unit starts counting from one again as if time starts again.<ref>{{Cite web |title=Regnal Years - The University of Nottingham |url=https://www.nottingham.ac.uk/manuscriptsandspecialcollections/researchguidance/datingdocuments/regnalyears.aspx |access-date=2023-12-11 |website=www.nottingham.ac.uk}}</ref> The use of [[regnal year]]s is a rather impractical system, and a challenge for historians if a single piece of the historical chronology is missing, and often reflects the preponderance in public life of an absolute ruler in many ancient cultures.  Such traditions sometimes outlive the political power of the throne, and may even be based on mythological events or rulers who may not have existed (for example Rome numbering from the rule of [[Romulus]] and [[Remus]]).<ref name=":2" /> In a manner of speaking the use of the supposed date of the birth of Christ as a base year is a form of an era.

In [[East Asia]], each emperor's reign may be subdivided into several reign periods, each being treated as a new era.<ref>{{Cite web |title=Calendar systems and their role in patent documentation {{!}} Epo.org |url=https://www.epo.org/en/searching-for-patents/helpful-resources/patent-knowledge-news/calendar-systems-and-their-role |access-date=2023-12-11 |website=www.epo.org}}</ref> The name of each was a motto or slogan chosen by the emperor. Different East Asian countries utilized slightly different systems, notably:

*[[Chinese era name|Chinese eras]]
*[[Japanese era name|Japanese era]]
*[[Korean era name|Korean eras]]
*[[Vietnamese era name|Vietnamese eras]]

A similar practice survived in the United Kingdom until quite recently, but only for formal official writings: in daily life the ordinary year A.D. has been used for a long time, but [[Acts of Parliament]] were dated according to the years of the reign of the current [[Monarch of the United Kingdom|monarch]], so that "61 & 62 Vict c. 37" refers to the [[Local Government (Ireland) Act 1898]]<ref name="beckett">{{cite book |last=Beckett |first=J C |title=The Making of Modern Ireland 1603 – 1923 |publisher=Faber & Faber |year=1966 |isbn=0-571-09267-5 |location=London |page=406}}</ref> passed in the session of [[Parliament of the United Kingdom|Parliament]] in the 61st/62nd year of the reign of [[Victoria of the United Kingdom|Queen Victoria]].<ref>{{cite book |title=Sweet & Maxwell's Guide to Law Reports and Statutes |publisher=Sweet & Maxwell's Guide |year=1962 |edition=Fourth |location=London |pages=20–33 |chapter=Chapter Five: Table of regnal year of English Sovereigns |ref={{harvid|Sweet & Maxwell's Guide|1962}} |chapter-url=https://guides.library.harvard.edu/ld.php?content_id=12548485}}</ref>