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class="vector-toc-numb">2</span> <span>Historical reforms</span> </div> </a> <button aria-controls="toc-Historical_reforms-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Historical reforms subsection</span> </button> <ul id="toc-Historical_reforms-sublist" class="vector-toc-list"> <li id="toc-Reform_of_lunar_and_lunisolar_calendars" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Reform_of_lunar_and_lunisolar_calendars"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Reform of lunar and lunisolar calendars</span> </div> </a> <ul id="toc-Reform_of_lunar_and_lunisolar_calendars-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Julian_and_Gregorian_reforms" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Julian_and_Gregorian_reforms"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Julian and Gregorian reforms</span> </div> </a> <ul id="toc-Julian_and_Gregorian_reforms-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Proposals" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Proposals"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Proposals</span> </div> </a> <button aria-controls="toc-Proposals-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Proposals subsection</span> </button> <ul id="toc-Proposals-sublist" class="vector-toc-list"> <li id="toc-Perennial_calendars" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Perennial_calendars"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Perennial calendars</span> </div> </a> <ul id="toc-Perennial_calendars-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-10-month_calendars" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#10-month_calendars"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>10-month calendars</span> </div> </a> <ul id="toc-10-month_calendars-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-12-month_calendars" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#12-month_calendars"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>12-month calendars</span> </div> </a> <ul id="toc-12-month_calendars-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-13-month_calendars" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#13-month_calendars"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>13-month calendars</span> </div> </a> <ul id="toc-13-month_calendars-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Lunisolar_calendars" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Lunisolar_calendars"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Lunisolar calendars</span> </div> </a> <ul id="toc-Lunisolar_calendars-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Naming" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Naming"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>Naming</span> </div> </a> <ul id="toc-Naming-sublist" class="vector-toc-list"> <li id="toc-Examples" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Examples"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6.1</span> <span>Examples</span> </div> </a> <ul id="toc-Examples-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Specific_proposals" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Specific_proposals"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.7</span> <span>Specific proposals</span> </div> </a> <ul id="toc-Specific_proposals-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc 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mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. 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article badge"><a href="https://et.wikipedia.org/wiki/Kalendrireform" title="Kalendrireform – Estonian" lang="et" hreflang="et" data-title="Kalendrireform" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Reformaj_proponoj_de_la_gregoria_kalendaro" title="Reformaj proponoj de la gregoria kalendaro – Esperanto" lang="eo" hreflang="eo" data-title="Reformaj proponoj de la gregoria kalendaro" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%BE%D8%B1%D9%88%DA%98%D9%87%E2%80%8C%D9%87%D8%A7%DB%8C_%D8%AA%D9%82%D9%88%DB%8C%D9%85_%D9%BE%D8%A7%DB%8C%D8%AF%D8%A7%D8%B1_%D8%AC%D9%87%D8%A7%D9%86%DB%8C" title="پروژه‌های تقویم پایدار جهانی – Persian" lang="fa" hreflang="fa" data-title="پروژه‌های تقویم پایدار جهانی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EA%B0%9C%EB%A0%A5" title="개력 – Korean" lang="ko" hreflang="ko" data-title="개력" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Reforma_kalendara" title="Reforma kalendara – Croatian" lang="hr" hreflang="hr" data-title="Reforma kalendara" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E6%94%B9%E6%9A%A6" title="改暦 – Japanese" lang="ja" hreflang="ja" data-title="改暦" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Kalenderreform" title="Kalenderreform – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Kalenderreform" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D1%80%D0%BE%D0%B5%D0%BA%D1%82%D1%8B_%D1%81%D1%82%D0%B0%D0%B1%D0%B8%D0%BB%D1%8C%D0%BD%D0%BE%D0%B3%D0%BE_%D0%BA%D0%B0%D0%BB%D0%B5%D0%BD%D0%B4%D0%B0%D1%80%D1%8F" title="Проекты стабильного календаря – Russian" lang="ru" hreflang="ru" data-title="Проекты стабильного календаря" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Reforma_kalendara" title="Reforma kalendara – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Reforma kalendara" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Kalenderreform" title="Kalenderreform – Swedish" lang="sv" hreflang="sv" data-title="Kalenderreform" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9A%D0%B0%D0%BB%D0%B5%D0%BD%D0%B4%D0%B0%D1%80%D0%BD%D0%B0_%D1%80%D0%B5%D1%84%D0%BE%D1%80%D0%BC%D0%B0" 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.ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Calendar_reform" title="Special:EditPage/Calendar reform">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a>. Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22Calendar+reform%22">"Calendar reform"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Calendar+reform%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Calendar+reform%22&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22Calendar+reform%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Calendar+reform%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Calendar+reform%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">June 2021</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <p> <b>Calendar reform</b> or <b>calendrical reform</b> is any significant revision of a <a href="/wiki/Calendar" title="Calendar">calendar</a> system. The term sometimes is used instead for a proposal to switch to a different calendar design. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Principles">Principles</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Calendar_reform" title="Special:EditPage/Calendar reform">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22Calendar+reform%22">"Calendar reform"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Calendar+reform%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Calendar+reform%22&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22Calendar+reform%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Calendar+reform%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Calendar+reform%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">September 2019</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <p>The prime objective of a calendar is to unambiguously identify any <a href="/wiki/Day" title="Day">day</a> in past, present and future by a specific date in order to record or organize social, religious, commercial or administrative events. Recurring periods that contain multiple days, such as <a href="/wiki/Week" title="Week">weeks</a>, <a href="/wiki/Month" title="Month">months</a>, and <a href="/wiki/Year" title="Year">years</a>, are secondary, convenient features of a calendar. Most cultures adopt a primary dating system, but different cultures have always needed to align multiple calendars with each other, either because they coexisted in the same space (e.g. secular and religious groups with different demands) or had established trading relations. </p><p>Once specified, a <i>calendar design</i> cannot be altered without becoming a new design. If a proposed design is sufficiently close to the legacy one, i.e. compatible with it, a <i>reform</i> of the local <i>calendar system</i> is possible without disruption. Examples of this include the changes to the <a href="/wiki/Chinese_calendar" title="Chinese calendar">Chinese calendar</a> due to problems between regions in China and practical changes in religious calendars such as the <a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic calendar</a>, where the start of the month is now derived from astronomical data rather than sightings by religious leaders.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>Some design changes, however, will yield date identifiers different from the previous design for some days, often in the distant past or future. </p><p>The calendar system must clarify whether dates are changed to the new design retroactively (using a <i>proleptic calendar</i>) or whether the design in use then and there shall be respected. Calendar schisms happen if not all cultures that adopted a common calendar system before perform a calendar reform at the same time. If date identifiers are similar but different, confusion and mistakes are unavoidable. </p><p>Most calendars have several rules which could be altered by reform: </p> <ul><li>Whether and how days are grouped into subdivisions such as months and weeks, and days outside those subdivisions, if any.</li> <li>Which years are <a href="/wiki/Leap_year" title="Leap year">leap years</a> and <a href="/wiki/Common_year" title="Common year">common years</a> and how they differ.</li> <li>Numbering of years, selection of the <a href="/wiki/Epoch_(reference_date)" class="mw-redirect" title="Epoch (reference date)">epoch</a>, and the issue of <a href="/wiki/0_(year)" class="mw-redirect" title="0 (year)">year zero</a>.</li> <li>Start of the year (such as the <a href="/wiki/December_solstice" title="December solstice">December solstice</a>, January 1, March 1, <a href="/wiki/March_equinox" title="March equinox">March equinox</a>, <a href="/wiki/Lady_Day" title="Lady Day">Lady Day</a>).</li> <li>If a week is retained, the start, length, and names of its days.</li> <li>Start of the day (midnight, sunrise, noon, or sunset).</li> <li>If months are retained, number, lengths, and names of months.</li> <li>Special days and periods (such as leap day or intercalary day).</li> <li>Alignment with social cycles.</li> <li>Alignment with astronomical cycles.</li> <li>Alignment with biological cycles.</li> <li>Literal notation of dates.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Historical_reforms">Historical reforms</h2></div> <p>Historically, most calendar reforms have been made in order to synchronize the calendar with the astronomical year (either <a href="/wiki/Solar_year" class="mw-redirect" title="Solar year">solar</a> or <a href="/wiki/Sidereal_year" title="Sidereal year">sidereal</a>) and/or the <a href="/wiki/Synodic_month" class="mw-redirect" title="Synodic month">synodic month</a> in <a href="/wiki/Lunar_calendar" title="Lunar calendar">lunar</a> or <a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">lunisolar calendars</a>. Most reforms for calendars have been to make them more accurate. This has happened to various lunar and lunisolar calendars, and also the <a href="/wiki/Julian_calendar" title="Julian calendar">Julian calendar</a>, when it was altered to the <a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian calendar</a>. </p><p>The fundamental problems of the calendar are that the astronomical year has neither a whole number of days nor a whole number of lunar months; neither does the lunar month have a whole number of days: in each case there are fractions "left over". (In some physical circumstances the rotations and revolutions of a planet and its satellite(s) can be phase-locked – for example the same side of the moon always faces us – but this has not operated to lock together the lengths of the Earth's year, day and month.) Such remainders could accumulate from one period to the next, thereby driving the cycles out of synchronization. </p><p>A typical solution to force synchronization is <a href="/wiki/Intercalation_(timekeeping)" title="Intercalation (timekeeping)">intercalation</a>. This means occasionally adding an extra day, week, or month into the cycle. An alternative approach is to ignore the mismatch and simply let the cycles continue to drift apart. The general approaches include: </p> <ul><li>The lunar calendar, which fits days into the cycle of lunar months, adding an extra day when needed, while ignoring the annual solar cycle of the seasons.</li> <li>The solar calendar, which fits artificial months into the year, adding an extra day into one month when needed, while ignoring the lunar cycle of new/full moons.</li> <li>The lunisolar calendar, which keeps both the lunar and solar cycles, adding an extra month into the year when needed.</li></ul> <p>An obvious disadvantage of the lunisolar method of inserting a whole extra month is the large irregularity of the length of the year from one to the next. The simplicity of a lunar calendar has always been outweighed by its inability to track the seasons, and a solar calendar is used in conjunction to remedy this defect. Identifying the lunar cycle month requires straightforward observation of the Moon on a clear night. However, identifying seasonal cycles requires much more methodical observation of stars or a device to track solar day-to-day progression, such as that established at places like <a href="/wiki/Stonehenge" title="Stonehenge">Stonehenge</a>. After centuries of empirical observations, the theoretical aspects of calendar construction could become more refined, enabling predictions that identified the need for reform. </p> <div class="mw-heading mw-heading3"><h3 id="Reform_of_lunar_and_lunisolar_calendars">Reform of lunar and lunisolar calendars</h3></div> <p>There have been 50 to 100 reforms of the traditional <a href="/wiki/Chinese_calendar" title="Chinese calendar">Chinese calendar</a> over 2500 years, most of which were intended to better fit the calendar months to astronomical lunations and to more accurately add the extra month so that the regular months maintain their proper seasonal positions, even though each seasonal marker can occur anywhere within its month. There have been at least four similar reforms of the lunisolar version of the <a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu calendar</a>, all intended to make the month a better match to the lunation and to make the year a better fit to the <i>sidereal</i> year. There have been reforms of the <i>solar</i> version of the Hindu calendar which changed the distribution of the days in each month to better match the length of time that the Sun spends in each <i>sidereal</i> zodiacal sign. The same applies to the <a href="/wiki/Buddhist_calendar" title="Buddhist calendar">Buddhist calendar</a>. The first millennium reform of the <a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew calendar</a> changed it from an observational calendar into a calculated calendar. The <a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic calendar</a> was a reform of the preceding lunisolar calendar which completely divorced it from the solar year. </p><p>Another reform was performed in <a href="/wiki/Seljuq_Empire" class="mw-redirect" title="Seljuq Empire">Seljuk Persia</a> by <a href="/wiki/Omar_Khayyam" title="Omar Khayyam">Omar Khayyam</a> and others, developing the precisely computed <a href="/wiki/Jalali_calendar" title="Jalali calendar">Jalali calendar</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Julian_and_Gregorian_reforms">Julian and Gregorian reforms</h3></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:William_Hogarth_028.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/William_Hogarth_028.jpg/220px-William_Hogarth_028.jpg" decoding="async" width="220" height="175" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/William_Hogarth_028.jpg/330px-William_Hogarth_028.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/63/William_Hogarth_028.jpg/440px-William_Hogarth_028.jpg 2x" data-file-width="2024" data-file-height="1607" /></a><figcaption><a href="/wiki/William_Hogarth" title="William Hogarth">William Hogarth</a>'s <i><a href="/wiki/Humours_of_an_Election" title="Humours of an Election">An Election Entertainment</a></i> includes a banner with the protest slogan against the Gregorian calendar: "Give us our Eleven days" (on floor at lower right)</figcaption></figure> <p>When <a href="/wiki/Julius_Caesar" title="Julius Caesar">Julius Caesar</a> took power in Rome, the <a href="/wiki/Roman_calendar" title="Roman calendar">Roman calendar</a> had ceased to reflect the year accurately.<sup id="cite_ref-roman_2-0" class="reference"><a href="#cite_note-roman-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>The <a href="/wiki/Julian_calendar" title="Julian calendar">Julian reform</a> made 46 BC 445 days long and replaced the intercalary month with an intercalary day to be inserted within February every four years. This produced a noticeably more accurate calendar, but it had an average year length of 365 days and six hours (365.25 days), which had the effect of adding about three-quarters of an hour every four years. The effect accumulated from inception in 45 BC until by the 16th century the northward equinox was falling on March 10 or 11. </p><p>Under <a href="/wiki/Pope_Gregory_XIII" title="Pope Gregory XIII">Pope Gregory XIII</a>, the <a href="/wiki/Gregorian_calendar" title="Gregorian calendar">leap year rule was altered</a>: only centennial years evenly divisible by 400 are leap years. Thus, the years 1600, 2000, 2400 and 2800 are <a href="/wiki/Leap_year" title="Leap year">leap years</a>, while 1700, 1800, 1900, 2100, 2200, 2300, 2500, 2600, 2700, 2900, and 3000 are <a href="/wiki/Common_year" title="Common year">common years</a> despite being divisible by 4. This rule makes the mean year 365.2425 days <span class="nowrap">(365 d, 5 h, 49 min, 12 s)</span> long. While this does not synchronize the years entirely, it would require a few thousand years to accumulate a day.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p> So that the northward equinox would have the same date in the new Gregorian calendar as it had when the Council of Nicaea made recommendations in AD 325 (<span class="nowrap">March 21</span>), ten days were dropped so that <span class="nowrap">October 5</span> became <span class="nowrap">October 15</span> in 1582. </p><figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Julian_to_Gregorian_Date_Change.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/69/Julian_to_Gregorian_Date_Change.png/220px-Julian_to_Gregorian_Date_Change.png" decoding="async" width="220" height="116" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/69/Julian_to_Gregorian_Date_Change.png/330px-Julian_to_Gregorian_Date_Change.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/69/Julian_to_Gregorian_Date_Change.png/440px-Julian_to_Gregorian_Date_Change.png 2x" data-file-width="887" data-file-height="468" /></a><figcaption>Julian to Gregorian Date Change</figcaption></figure><p> This reform took a few centuries to spread through the nations that used the Julian calendar, although the Russian church year still uses the Julian calendar. Those nations that adopted this calendar on or after 1700, had to drop more than ten days: Great Britain, for instance, dropped eleven.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>In 1923, <a href="/wiki/Milutin_Milankovi%C4%87" title="Milutin Milanković">Milutin Milanković</a> proposed to a <a href="/wiki/Synod" title="Synod">synod</a> of some <a href="/wiki/Eastern_Orthodox_Church" title="Eastern Orthodox Church">Eastern Orthodox Churches</a> at <a href="/wiki/Constantinople" title="Constantinople">Constantinople</a> that only centennial years that leave a remainder of 200 or 600 upon division by 900 would be leap years, decreasing the average year length to 365.24<span style="text-decoration:overline;">2</span> days: these remainders were chosen to delay as much as possible the first year (after the year of 1923) that this calendar would disagree with the Gregorian calendar, which occurs in until 2800. It was adopted by some Eastern Orthodox Churches, under the names <a href="/wiki/Revised_Julian_calendar" title="Revised Julian calendar">Revised Julian calendar</a> or New calendar, but was rejected by others. </p> <div class="mw-heading mw-heading2"><h2 id="Proposals">Proposals</h2></div> <p>The <a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian calendar</a> is currently used by most of the world. There is also an international standard describing the calendar, <a href="/wiki/ISO_8601" title="ISO 8601">ISO 8601</a>, with some differences from traditional conceptions in many cultures. </p><p>Since the papal reform in 1582, several proposals have been offered to make the Gregorian calendar more useful or regular. Very few reforms have gained official acceptance. The rather different <a href="/wiki/Decimal_calendar" title="Decimal calendar">decimal</a> <a href="/wiki/French_Republican_Calendar" class="mw-redirect" title="French Republican Calendar">French Republican Calendar</a> was one such official reform, but was abolished twelve years later by <a href="/wiki/Napoleon" title="Napoleon">Napoleon</a>. After <a href="/wiki/World_War_II" title="World War II">World War II</a>, the newly formed United Nations continued efforts of its predecessor, the <a href="/wiki/League_of_Nations" title="League of Nations">League of Nations</a>, to establish the proposed <a href="/wiki/World_Calendar" title="World Calendar">World Calendar</a> but postponed the issue after a veto from the <a href="/wiki/Federal_government_of_the_United_States" title="Federal government of the United States">government of the United States</a>, which was mainly based upon concerns of religious groups about the proposed days that would be outside the seven-day week cycle ("blank days") and thus disrupt having a sabbath every seven days. Independently the <a href="/wiki/World_Council_of_Churches" title="World Council of Churches">World Council of Churches</a> still tries to find a common rule for the date of Easter,<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> which might be eased by a new common calendar. </p><p>Reformers cite several problems with the Gregorian calendar: </p> <ul><li>It is not <a href="/wiki/Perennial_Calendar" class="mw-redirect" title="Perennial Calendar">perennial</a>. Each year starts on a different day of the week and calendars expire every year.</li> <li>It is difficult to determine the weekday of any given day of the year or month.</li> <li>Months are not equal in length, nor regularly distributed across the year, and so some people rely on <a href="/wiki/Mnemonic" title="Mnemonic">mnemonics</a> (e.g., "<a href="/wiki/Thirty_days_hath_September" class="mw-redirect" title="Thirty days hath September">Thirty days hath September</a>" or <a href="/wiki/Knuckle_mnemonic" title="Knuckle mnemonic">knuckle counting</a>) to remember the lengths of months.</li> <li>The year's four quarters (of three full months each) are not equal (being of 90/91, 91, 92 and 92 days respectively). <a href="/wiki/Business_quarter" class="mw-redirect" title="Business quarter">Business quarters</a> that are equal would make accounting easier.</li> <li>Its epoch, i.e. start of the year count, is religious. The same applies to month and <a href="/wiki/Weekday" class="mw-redirect" title="Weekday">weekday</a> names in many languages.</li> <li>Each month has no connection with the <a href="/wiki/Lunar_phase" title="Lunar phase">lunar phases</a>.</li> <li>Solstices and equinoxes do not coincide with either the beginning of the Gregorian months or the midpoint of the months.</li> <li>The calendar does not have a <a href="/wiki/Year_Zero" class="mw-redirect" title="Year Zero">year zero</a>: the year after <a href="/wiki/1_BC" title="1 BC">1 BC</a> was <a href="/wiki/1_AD" class="mw-redirect" title="1 AD">1 AD</a>, with nothing in between them.</li></ul> <p>It is hard or even impossible to solve all these issues in just one calendar. </p><p>Most plans evolve around the solar year of a little more than 365 days. This number does not divide well by seven or twelve, which are the traditional numbers of days per week and months per year respectively. The nearby numbers 360, 364 and 366 are divisible in better ways. There are also lunar-centric proposals. </p> <div class="mw-heading mw-heading3"><h3 id="Perennial_calendars">Perennial calendars</h3></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Perennial_calendar" title="Perennial calendar">Perennial calendar</a></div> <p>Many calendar reforms have offered solutions to make the Gregorian calendar perennial. These reforms would make it easy to work out the day of the week of a particular <a href="/wiki/Calendar_date" title="Calendar date">date</a>, and would make changing calendars each year unnecessary. There are, roughly speaking, two options to achieve this goal: <a href="/wiki/Leap_week_calendar" title="Leap week calendar">leap week calendars</a> and <a href="/wiki/Intercalation_(timekeeping)" title="Intercalation (timekeeping)">intercalary days</a>. Leap week calendars add a leap week of seven days to the calendar every five or six years to keep the calendar roughly in step with the tropical year. They have years of either 364 days (52 weeks) or 371 days (53 weeks), thus preserving the 7-day week. </p><p>Proposals mainly differ in their selection of a leap rule, placing of the leap item (usually middle or end of the year), in the start day of the week and year, in the number (12 or 13) and size of months and in connected naming; some are compatible to the <a href="/wiki/Week_date" class="mw-redirect" title="Week date">week date</a> of ISO 8601. </p><p>The <a href="/wiki/World_Calendar" title="World Calendar">World Calendar</a>, favored by the UN in the 1950s, and the <a href="/wiki/International_Fixed_Calendar" title="International Fixed Calendar">International Fixed Calendar</a>, quite popular among economists between the World Wars, are proposals that start each year on a Sunday. The 364 days within the week system form 52 weeks of 7 days. The World Calendar has every quarter beginning on the same day of the week. In the World Calendar, the 365th and 366th day are considered holidays and named Worlds Day and Leap Year Day. These "off-calendar" days stand outside the seven-day week and caused some religious groups to strongly oppose adoption of the World Calendar. Such concerns helped prevent the World Calendar from being adopted. Supporters of the World Calendar, however, argue that the religious groups' opposition overlooked every individual's right to celebrate these holidays as extra days of worship, or <a href="/wiki/Sabbath" title="Sabbath">Sabbaths</a>. This option, they reason, maintained the seven-day worship cycle for those who share that concern, while allowing benefits of a perennial calendar to be shared by all. </p><p>Some calendar reform ideas, such as the <a href="/wiki/Pax_Calendar" title="Pax Calendar">Pax Calendar</a>, <a href="/wiki/Symmetry454" title="Symmetry454">Symmetry454</a> calendar and the <a href="/wiki/Hanke%E2%80%93Henry_Permanent_Calendar" title="Hanke–Henry Permanent Calendar">Hanke–Henry Permanent Calendar</a>, were created to solve this problem by having years of either 364 days (52 weeks) or 371 days (53 weeks), thus preserving the 7-day week. The 53-week calendar, used in government and in business for <a href="/wiki/Fiscal_year" title="Fiscal year">fiscal years</a>, is a variant of this concept. Each year of this calendar can be up to 371 days long. </p><p>Some calendars have quarters of regularly patterned uneven months e.g., a 35-day (five-week) month and a pair of 28-day (four-week) months, with a leap week appended to the final month when needed. The Common Civil Calendar and Time calendar has months of 30 and 31 days, but inserts a leap week in the middle of the year, when needed, whereas its successor, the Hanke–Henry Permanent Calendar, moves the extra week to the end of the year. </p><p>In the <a href="/wiki/World_Season_Calendar" class="mw-redirect" title="World Season Calendar">World Season Calendar</a>, months are discarded altogether; instead, the year is divided into four seasons of 13 weeks each. An extra day (two days during leap year) is added to the calendar that is not assigned a day of the week in order to perennialize the calendar. The same calendar of 91 days is used for each season of every year. </p> <div class="mw-heading mw-heading3"><h3 id="10-month_calendars">10-month calendars</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Decimal_calendar" title="Decimal calendar">Decimal calendar</a></div> <p>A decimal calendar is a calendar which includes <a href="/wiki/Unit_of_time" title="Unit of time">units of time</a> based on the <a href="/wiki/Decimal" title="Decimal">decimal system</a>. </p><p>The <a href="/wiki/French_Republican_Calendar" class="mw-redirect" title="French Republican Calendar">French Republican Calendar</a> was introduced (along with <a href="/wiki/Decimal_time" title="Decimal time">decimal time</a>) in 1793.<sup id="cite_ref-French_6-0" class="reference"><a href="#cite_note-French-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> It consisted of twelve months, each divided into three <i>décades</i> of ten days, with five or six intercalary days called <i><a href="/wiki/Sansculottides" title="Sansculottides">sansculottides</a></i>.<sup id="cite_ref-French_6-1" class="reference"><a href="#cite_note-French-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The calendar was abolished by <a href="/wiki/Napoleon" title="Napoleon">Napoleon</a> on January 1, 1806.<sup id="cite_ref-French_6-2" class="reference"><a href="#cite_note-French-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="12-month_calendars">12-month calendars</h3></div> <p>The lengths of the months inherited from the old <a href="/wiki/Roman_calendar" title="Roman calendar">Roman calendar</a> as reformed by Julius Caesar do not follow any apparent logic systematically. Many reform proposals seek to make the pattern more uniform. When keeping the traditional dozen months and the close approximation of a solar year, this usually yields four equal quarters of three months each where one month is longer than the other two. <a href="/wiki/World_Calendar" title="World Calendar">World Calendar</a> and <a href="/wiki/Hanke%E2%80%93Henry_Permanent_Calendar" title="Hanke–Henry Permanent Calendar">Hanke–Henry Permanent Calendar</a> follow this with 31:30:30 and 30:30:31 days per month, respectively. On the other hand, <a href="/wiki/Symmetry454" title="Symmetry454">Symmetry454</a> uses 4:5:4 weeks per month. They all result in 364 systematically distributed days and hence have to add either one extra and one leap day or a leap week. </p> <div class="mw-heading mw-heading3"><h3 id="13-month_calendars">13-month calendars</h3></div> <p>Some calendar reformers seek to equalize the length of each month in the year. This is often accomplished by creating a calendar that has 13 months of 4 weeks (28 days) each, making 364 days. The earliest known proposal of this type was the Georgian Calendar (1745)<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> by <a href="/wiki/Hugh_Jones_(reverend)" class="mw-redirect" title="Hugh Jones (reverend)">Rev. Hugh Jones</a>. </p><p>The <a href="/wiki/Positivist_calendar" title="Positivist calendar">Positivist calendar</a> (1849), created by <a href="/wiki/Auguste_Comte" title="Auguste Comte">Auguste Comte</a>, was based on a 364-day year which included one or two "blank" days. Each of the 13 months had 28 days and exactly four weeks, and each started on a Monday. The <a href="/wiki/International_Fixed_Calendar" title="International Fixed Calendar">International Fixed Calendar</a> is a more modern descendant of this calendar: invented by <a href="/wiki/Moses_B._Cotsworth" title="Moses B. Cotsworth">Moses B. Cotsworth</a> and financially backed by <a href="/wiki/George_Eastman" title="George Eastman">George Eastman</a>.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>Around 1930, one James Colligan invented the <a href="/wiki/Pax_Calendar" title="Pax Calendar">Pax Calendar</a>, which avoids off-calendar days by adding a 7-day <a href="/wiki/Leap_week_calendar" title="Leap week calendar">leap week</a> to the 364-day common year for 71 out of 400 years. </p> <div class="mw-heading mw-heading3"><h3 id="Lunisolar_calendars">Lunisolar calendars</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar calendar</a></div> <p>Lunisolar calendars usually have 12 or 13 months of 29 or 30 days. </p><p>The <a href="/wiki/Hermetic_Lunar_Week_Calendar" class="mw-redirect" title="Hermetic Lunar Week Calendar">Hermetic Lunar Week Calendar</a> is a lunisolar calendar proposal which has 12 or 13 lunar months of 29 or 30 days a year, and begins each year near the <a href="/wiki/March_equinox" title="March equinox">vernal equinox</a>.<sup id="cite_ref-auto_9-0" class="reference"><a href="#cite_note-auto-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p><p>The Meyer–Palmen Solilunar Calendar has 12 lunar months with 29 or 30 days plus a leap month called <a href="/wiki/Meton" class="mw-redirect" title="Meton">Meton</a> every 3 or 2 years with 30 or 31 days. 60 years together are called a cycle. It uses a leap cycle which has equal number of days, weeks, months, years and cycles. 2498258 days, 356894 weeks, 84599 months, 6840 years and 114 cycles nearly all equal each other. It is called an era, although time isn't divided into it in this calendar.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>Some propose to improve leap rules of existing calendars, such as the <a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew calendar</a>. The <a href="/wiki/Rectified_Hebrew_calendar" class="mw-redirect" title="Rectified Hebrew calendar">Rectified Hebrew calendar</a> uses a more accurate leap cycle of 4366 months per 353-year cycle, with 130 leap years per cycle, and a progressively shorter <i><a href="/wiki/Molad" title="Molad">molad</a></i> interval, intended to replace the 19-year leap cycle and the constant <i>molad</i> interval of the traditional fixed arithmetic Hebrew calendar, respectively. </p> <div class="mw-heading mw-heading3"><h3 id="Naming">Naming</h3></div> <p>Calendar proposals that introduce a thirteenth month or change the Julian-Gregorian system of months often also propose new names for these months. New names have also been proposed for days out of the week cycle (e.g., 365th and leap) and weeks out of the month cycle. </p><p>Proposals to change the traditional month and weekday names are less frequent. The Gregorian calendar obtains its names mostly from gods of historical religions (e.g., Thursday from Nordic <a href="/wiki/Thor" title="Thor">Thor</a> or March from Roman <a href="/wiki/Mars_(god)" class="mw-redirect" title="Mars (god)">Mars</a>) or leaders of vanished empires (July and August from the first Caesars), or ordinals that got out of synchronization (September through December, originally seventh through tenth, now ninth through twelfth). </p> <div class="mw-heading mw-heading4"><h4 id="Examples">Examples</h4></div> <p>Comte's Positivist calendar, for example, proposed naming the 13 months in his calendar after figures from religion, literature, philosophy and science. Similarly, the <a href="/wiki/Hermetic_Lunar_Week_Calendar" class="mw-redirect" title="Hermetic Lunar Week Calendar">Hermetic Lunar Week Calendar</a> uses 12 or 13 lunar months named after 13 contributors to research on <a href="/wiki/Psychoactive_plant" title="Psychoactive plant">psychoactive plants</a> and chemicals.<sup id="cite_ref-auto_9-1" class="reference"><a href="#cite_note-auto-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Specific_proposals">Specific proposals</h3></div> <p>There have been many specific calendar proposals to replace the Gregorian calendar: </p><p>The following count one or more days outside the standard seven-day week: </p> <ul><li><a href="/wiki/International_Fixed_Calendar" title="International Fixed Calendar">International Fixed Calendar</a><sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Invariable_Calendar" title="Invariable Calendar">Invariable Calendar</a><sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Positivist_calendar" title="Positivist calendar">Positivist calendar</a><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/World_Calendar" title="World Calendar">World Calendar</a><sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/World_Season_Calendar" class="mw-redirect" title="World Season Calendar">World Season Calendar</a><sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup></li></ul> <p>The following are leap week calendars: </p> <ul><li><a href="/wiki/Hanke%E2%80%93Henry_Permanent_Calendar" title="Hanke–Henry Permanent Calendar">Hanke–Henry Permanent Calendar</a><sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Pax_Calendar" title="Pax Calendar">Pax Calendar</a><sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Symmetry454" title="Symmetry454">Symmetry454</a><sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup></li></ul> <p>There have also been proposals to revise the way years are numbered: </p> <ul><li><a href="/wiki/Anno_Lucis" title="Anno Lucis">Anno Lucis</a><sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Holocene_calendar" title="Holocene calendar">Holocene calendar</a><sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup></li></ul> <p>Reform of the Islamic calendar: </p> <ul><li>Since the beginning of the 21st century, there is a trend within the Muslim communities of North America and Europe to substitute a lunar calendar based on calculations for the traditional Islamic method of monthly observation of the new moon to declare the beginning of the new month in each country separately.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div> <ul><li><a href="/wiki/Abolition_of_time_zones" title="Abolition of time zones">Abolition of time zones</a></li> <li><a href="/wiki/Determination_of_the_day_of_the_week" title="Determination of the day of the week">Determination of the day of the week</a></li> <li><a href="/wiki/Decimal_calendar" title="Decimal calendar">Decimal calendar</a></li> <li><a href="/wiki/Hanke%E2%80%93Henry_Permanent_Calendar" title="Hanke–Henry Permanent Calendar">Hanke–Henry Permanent Calendar</a></li> <li><a href="/wiki/List_of_calendars" title="List of calendars">List of calendars</a></li> <li><a href="/wiki/Metric_time" title="Metric time">Metric time</a></li></ul> <dl><dt>Precursors of the Gregorian reform</dt></dl> <ul><li><a href="/wiki/Johannes_de_Sacrobosco" title="Johannes de Sacrobosco">Johannes de Sacrobosco</a>, <i>De Anni Ratione</i> ("On reckoning the years"), c. 1235</li> <li><a href="/wiki/Roger_Bacon" title="Roger Bacon">Roger Bacon</a>, <i><a href="/wiki/Opus_Majus" title="Opus Majus">Opus Majus</a></i> ("Greater Work"), c. 1267</li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFRichards1998" class="citation book cs1">Richards, E. G. (1998). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/mappingtimecalen00rich"><i>Mapping Time: The Calendar and its History</i></a></span>. Oxford University Press. Ch. 18. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0192862051" title="Special:BookSources/978-0192862051"><bdi>978-0192862051</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Mapping+Time%3A+The+Calendar+and+its+History&rft.pages=Ch.+18&rft.pub=Oxford+University+Press&rft.date=1998&rft.isbn=978-0192862051&rft.aulast=Richards&rft.aufirst=E.+G.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fmappingtimecalen00rich&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-roman-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-roman_2-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.webexhibits.org/calendars/calendar-christian.html#anchor-roman">"The Christian Calendar | Calendars"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">May 22,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Christian+Calendar+%26%23124%3B+Calendars&rft_id=http%3A%2F%2Fwww.webexhibits.org%2Fcalendars%2Fcalendar-christian.html%23anchor-roman&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text">Bonnie Blackburn and Leofranc Holford-Strevens, <i>The Oxford Companion to the Year</i>, corrected printing (Oxford University Press, 2013), 692.</span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGingerich1983" class="citation book cs1"><a href="/wiki/Owen_Gingerich" title="Owen Gingerich">Gingerich, Owen</a> (1983). "The Civil Reception of the Gregorian Calendar". In Coyne, G. V.; Hoskin, M. A.; O., Pedersen (eds.). <a rel="nofollow" class="external text" href="http://articles.adsabs.harvard.edu/full/book/grc../1983//0000279.000.html"><i>The Gregorian Reform of the Calendar: Proceedings of the Vatican Conference to Commemorate its 400th Anniversary 1582–1982</i></a>. Vatican Observatory. pp. 265–279.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=The+Civil+Reception+of+the+Gregorian+Calendar&rft.btitle=The+Gregorian+Reform+of+the+Calendar%3A+Proceedings+of+the+Vatican+Conference+to+Commemorate+its+400th+Anniversary+1582%E2%80%931982&rft.pages=265-279&rft.pub=Vatican+Observatory&rft.date=1983&rft.aulast=Gingerich&rft.aufirst=Owen&rft_id=http%3A%2F%2Farticles.adsabs.harvard.edu%2Ffull%2Fbook%2Fgrc..%2F1983%2F%2F0000279.000.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWorld_Council_of_Churches1997" class="citation web cs1">World Council of Churches (March 10, 1997). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20121012114307/http://www.oikoumene.org/en/resources/documents/wcc-commissions/faith-and-order-commission/i-unity-the-church-and-its-mission/towards-a-common-date-for-easter/towards-a-common-date-for-easter.html">"Towards a Common Date for Easter"</a>. <i>www.oikoumene.org</i>. Archived from <a rel="nofollow" class="external text" href="http://www.oikoumene.org/en/resources/documents/wcc-commissions/faith-and-order-commission/i-unity-the-church-and-its-mission/towards-a-common-date-for-easter/towards-a-common-date-for-easter.html">the original</a> on October 12, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">October 13,</span> 2007</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.oikoumene.org&rft.atitle=Towards+a+Common+Date+for+Easter&rft.date=1997-03-10&rft.au=World+Council+of+Churches&rft_id=http%3A%2F%2Fwww.oikoumene.org%2Fen%2Fresources%2Fdocuments%2Fwcc-commissions%2Ffaith-and-order-commission%2Fi-unity-the-church-and-its-mission%2Ftowards-a-common-date-for-easter%2Ftowards-a-common-date-for-easter.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-French-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-French_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-French_6-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-French_6-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSanja_Perovic2012" class="citation journal cs1">Sanja Perovic (2012). "French Republican Calendar: Time, History and the Revolutionary Event". <i>Journal for Eighteenth-Century Studies</i>. <b>35</b>: 1–16. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1111%2Fj.1754-0208.2011.00408.x">10.1111/j.1754-0208.2011.00408.x</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+for+Eighteenth-Century+Studies&rft.atitle=French+Republican+Calendar%3A+Time%2C+History+and+the+Revolutionary+Event&rft.volume=35&rft.pages=1-16&rft.date=2012&rft_id=info%3Adoi%2F10.1111%2Fj.1754-0208.2011.00408.x&rft.au=Sanja+Perovic&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://myweb.ecu.edu/mccartyr/hirossa.html">"The Georgian Calendar"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">February 2,</span> 2015</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Georgian+Calendar&rft_id=http%3A%2F%2Fmyweb.ecu.edu%2Fmccartyr%2Fhirossa.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text">Cook, Anna J. (1st August 2024) A Man Beyond Time: Moses B. Cotsworth's fight for the 13-month calendar, Independent Publishing Network ISBN 978-1-80517-720-3</span> </li> <li id="cite_note-auto-9"><span class="mw-cite-backlink">^ <a href="#cite_ref-auto_9-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-auto_9-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.hermetic.ch/cal_stud/hlwc/hlwc.htm">"The Hermetic Lunar Week Calendar"</a>. <i>www.hermetic.ch</i><span class="reference-accessdate">. Retrieved <span class="nowrap">June 21,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.hermetic.ch&rft.atitle=The+Hermetic+Lunar+Week+Calendar&rft_id=https%3A%2F%2Fwww.hermetic.ch%2Fcal_stud%2Fhlwc%2Fhlwc.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.hermetic.ch/cal_stud/nlsc/nlsc.htm">"The Meyer–Palmen Solilunar Calendar"</a>. <i>www.hermetic.ch</i><span class="reference-accessdate">. Retrieved <span class="nowrap">June 21,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.hermetic.ch&rft.atitle=The+Meyer%E2%80%93Palmen+Solilunar+Calendar&rft_id=https%3A%2F%2Fwww.hermetic.ch%2Fcal_stud%2Fnlsc%2Fnlsc.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSteel2000" class="citation book cs1">Steel, Duncan (2000). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/309"><i>Marking Time: The Epic Quest to Invent the Perfect Calendar</i></a></span>. New York: Wiley. p. <a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/309">309</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-471-29827-1" title="Special:BookSources/0-471-29827-1"><bdi>0-471-29827-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Marking+Time%3A+The+Epic+Quest+to+Invent+the+Perfect+Calendar&rft.place=New+York&rft.pages=309&rft.pub=Wiley&rft.date=2000&rft.isbn=0-471-29827-1&rft.aulast=Steel&rft.aufirst=Duncan&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fmarkingtimeepicq00stee_0%2Fpage%2F309&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://www.nytimes.com/1910/06/26/archives/a-proposed-plan-for-an-invariable-calendar-prof-la-grosclaude.html">"A PROPOSED PLAN FOR AN INVARIABLE CALENDAR; Prof. L.A. Grosclaude Offers an Interesting Suggestion to Solve the Troubles of the Present Division of Days"</a>. <i>New York Times</i>. June 26, 1910<span class="reference-accessdate">. Retrieved <span class="nowrap">October 4,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=New+York+Times&rft.atitle=A+PROPOSED+PLAN+FOR+AN+INVARIABLE+CALENDAR%3B+Prof.+L.A.+Grosclaude+Offers+an+Interesting+Suggestion+to+Solve+the+Troubles+of+the+Present+Division+of+Days.&rft.date=1910-06-26&rft_id=https%3A%2F%2Fwww.nytimes.com%2F1910%2F06%2F26%2Farchives%2Fa-proposed-plan-for-an-invariable-calendar-prof-la-grosclaude.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSteel2000" class="citation book cs1">Steel, Duncan (2000). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/308"><i>Marking Time: The Epic Quest to Invent the Perfect Calendar</i></a></span>. New York: Wiley. p. <a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/308">308</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-471-29827-1" title="Special:BookSources/0-471-29827-1"><bdi>0-471-29827-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Marking+Time%3A+The+Epic+Quest+to+Invent+the+Perfect+Calendar&rft.place=New+York&rft.pages=308&rft.pub=Wiley&rft.date=2000&rft.isbn=0-471-29827-1&rft.aulast=Steel&rft.aufirst=Duncan&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fmarkingtimeepicq00stee_0%2Fpage%2F308&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWorld_Calendar_Association" class="citation cs2">World Calendar Association, <a rel="nofollow" class="external text" href="http://www.theworldcalendar.org/"><i>The World Calendar.org</i></a>, theworldcalendar.org<span class="reference-accessdate">, retrieved <span class="nowrap">October 4,</span> 2019</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+World+Calendar.org&rft.pub=theworldcalendar.org&rft.au=World+Calendar+Association&rft_id=http%3A%2F%2Fwww.theworldcalendar.org%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAsimov1973" class="citation cs2">Asimov, Isaac (1973), <i>The Tragedy of the Moon</i>, Doubleday, pp. 48–58, <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1973trmo.book.....A">1973trmo.book.....A</a>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-440-18999-3" title="Special:BookSources/0-440-18999-3"><bdi>0-440-18999-3</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Tragedy+of+the+Moon&rft.pages=48-58&rft.pub=Doubleday&rft.date=1973&rft_id=info%3Abibcode%2F1973trmo.book.....A&rft.isbn=0-440-18999-3&rft.aulast=Asimov&rft.aufirst=Isaac&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPappas2011" class="citation web cs1">Pappas, Stephanie Pappas (December 29, 2011). <a rel="nofollow" class="external text" href="https://www.scientificamerican.com/article/is-it-time-to-overhaul/">"Is It Time to Overhaul the Calendar?"</a>. <i>Scientific American</i><span class="reference-accessdate">. Retrieved <span class="nowrap">October 4,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Scientific+American&rft.atitle=Is+It+Time+to+Overhaul+the+Calendar%3F&rft.date=2011-12-29&rft.aulast=Pappas&rft.aufirst=Stephanie+Pappas&rft_id=https%3A%2F%2Fwww.scientificamerican.com%2Farticle%2Fis-it-time-to-overhaul%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSteel2000" class="citation book cs1">Steel, Duncan (2000). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/288"><i>Marking Time: The Epic Quest to Invent the Perfect Calendar</i></a></span>. New York: Wiley. p. <a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/288">288</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-471-29827-1" title="Special:BookSources/0-471-29827-1"><bdi>0-471-29827-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Marking+Time%3A+The+Epic+Quest+to+Invent+the+Perfect+Calendar&rft.place=New+York&rft.pages=288&rft.pub=Wiley&rft.date=2000&rft.isbn=0-471-29827-1&rft.aulast=Steel&rft.aufirst=Duncan&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fmarkingtimeepicq00stee_0%2Fpage%2F288&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBromberg" class="citation cs2">Bromberg, Irv, <a rel="nofollow" class="external text" href="http://individual.utoronto.ca/kalendis/symmetry.htm"><i>The Symmetry454 Calendar</i></a>, University of Toronto<span class="reference-accessdate">, retrieved <span class="nowrap">October 4,</span> 2019</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Symmetry454+Calendar&rft.pub=University+of+Toronto&rft.aulast=Bromberg&rft.aufirst=Irv&rft_id=http%3A%2F%2Findividual.utoronto.ca%2Fkalendis%2Fsymmetry.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMasonic_Lodge_of_Education2019" class="citation cs2">Masonic Lodge of Education (2019), <a rel="nofollow" class="external text" href="https://www.masonic-lodge-of-education.com/masonic-calendar.html"><i>Masonic Calendar</i></a>, Masonic Lodge of Education<span class="reference-accessdate">, retrieved <span class="nowrap">October 4,</span> 2019</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Masonic+Calendar&rft.pub=Masonic+Lodge+of+Education&rft.date=2019&rft.au=Masonic+Lodge+of+Education&rft_id=https%3A%2F%2Fwww.masonic-lodge-of-education.com%2Fmasonic-calendar.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSteel2000" class="citation book cs1">Steel, Duncan (2000). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/149"><i>Marking Time: The Epic Quest to Invent the Perfect Calendar</i></a></span>. New York: Wiley. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/markingtimeepicq00stee_0/page/149">149–151</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-471-29827-1" title="Special:BookSources/0-471-29827-1"><bdi>0-471-29827-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Marking+Time%3A+The+Epic+Quest+to+Invent+the+Perfect+Calendar&rft.place=New+York&rft.pages=149-151&rft.pub=Wiley&rft.date=2000&rft.isbn=0-471-29827-1&rft.aulast=Steel&rft.aufirst=Duncan&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fmarkingtimeepicq00stee_0%2Fpage%2F149&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span></span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://tabsir.net/?p=1901">Khalid Chraibi, The Reform of the Islamic Calendar: The Terms of the Debate, Tabsir.net, September 2012</a>.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div> <ul><li>Segura, Wenceslao (2012). <a rel="nofollow" class="external text" href="http://www.alqantir.com/la_reforma_del_calendario.pdf"><i>La reforma del calendario</i></a>. <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-84-616-1729-6" title="Special:BookSources/978-84-616-1729-6">978-84-616-1729-6</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div> <ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20130605055717/http://www.kluznick.com/Calendar.html">Kluznickian Calendar</a> (very brief mention in New York Times op-ed page) (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://www.nytimes.com/2011/02/28/opinion/28hill.html?_r=0">"Except February"</a>. <i>New York Times</i>. February 27, 2011.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=New+York+Times&rft.atitle=Except+February&rft.date=2011-02-27&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2011%2F02%2F28%2Fopinion%2F28hill.html%3F_r%3D0&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACalendar+reform" class="Z3988"></span>)</li> <li><a rel="nofollow" class="external text" href="http://myweb.ecu.edu/mccartyr/calendar-reform.html">Home Page for Calendar Reform</a></li> <li><a rel="nofollow" class="external text" href="http://www.hermetic.ch/cal_stud/palmen/lweek1.htm">Leap week calendars</a> in which each year has either 364 or 371 days</li> <li><a rel="nofollow" class="external text" href="http://www.newadvent.org/cathen/03168a.htm"><i>Catholic Encyclopedia</i> "Reform of the Calendar"</a> Historical information</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist 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calendar">Lunar</a></li> <li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a></li> <li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">In wide use</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Astronomical_year_numbering" title="Astronomical year numbering">Astronomical</a></li> <li><a href="/wiki/Buddhist_calendar" title="Buddhist calendar">Buddhist</a></li> <li><a href="/wiki/Chinese_calendar" title="Chinese calendar">Chinese</a></li> <li><a href="/wiki/Ethiopian_calendar" title="Ethiopian calendar">Ethiopian</a></li> <li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Lunar Hijri</a></li> <li><a href="/wiki/Solar_Hijri_calendar" title="Solar Hijri calendar">Solar Hijri</a></li> <li><a href="/wiki/ISO_week_date" title="ISO week date">ISO</a></li> <li><a href="/wiki/Unix_time" title="Unix time">Unix time</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">In more<br />limited use</div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Akan_calendar" title="Akan calendar">Akan</a></li> <li><a href="/wiki/Armenian_calendar" title="Armenian calendar">Armenian</a></li> <li><a href="/wiki/Assamese_calendar" title="Assamese calendar">Assamese (Bhāshkarābda)</a></li> <li><a href="/wiki/Assyrian_calendar" title="Assyrian calendar">Assyrian</a></li> <li><a href="/wiki/Bah%C3%A1%CA%BC%C3%AD_calendar" title="Baháʼí calendar">Baháʼí</a> <ul><li>Badí‘</li></ul></li> <li>Bali <ul><li><a href="/wiki/Pawukon_calendar" title="Pawukon calendar">Pawukon</a></li> <li><a href="/wiki/Balinese_saka_calendar" title="Balinese saka calendar">Saka</a></li></ul></li> <li><a href="/wiki/Bengali_calendars" title="Bengali calendars">Bengali</a> <ul><li><a href="/wiki/Bangladeshi_calendar" class="mw-redirect" title="Bangladeshi calendar">Bangladeshi</a></li></ul></li> <li><a href="/wiki/Berber_calendar" title="Berber calendar">Berber</a></li> <li><a href="/wiki/Borana_calendar" title="Borana calendar">Borana</a></li> <li><a href="/wiki/Burmese_calendar" title="Burmese calendar">Burmese</a></li> <li><a href="/wiki/Chinese_calendar" title="Chinese calendar">Chinese</a> <ul><li><a href="/wiki/Earthly_Branches" title="Earthly Branches">Earthly Branches</a></li> <li><a href="/wiki/Heavenly_Stems" title="Heavenly Stems">Heavenly Stems</a></li> <li><a href="/wiki/Republic_of_China_calendar" title="Republic of China calendar">Minguo</a></li> <li><a href="/wiki/Solar_term" title="Solar term">Solar term</a></li></ul></li> <li><a href="/wiki/Heathen_holidays" title="Heathen holidays">Germanic heathen</a></li> <li><a href="/wiki/Georgian_calendar" title="Georgian calendar">Georgian</a></li> <li><a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu</a> <ul><li><a href="/wiki/Vikram_Samvat" title="Vikram Samvat">Vikram Samvat</a></li> <li><a href="/wiki/Indian_national_calendar" title="Indian national calendar">Saka</a></li></ul></li> <li><a href="/wiki/Hmong_calendar" title="Hmong calendar">Hmong</a></li> <li><a href="/wiki/Igbo_calendar" title="Igbo calendar">Igbo</a></li> <li><a href="/wiki/Iranian_calendars" title="Iranian calendars">Iranian</a> <ul><li><a href="/wiki/Jalali_calendar" title="Jalali calendar">Jalali</a> <ul><li>medieval</li></ul></li> <li><a href="/wiki/Zoroastrian_calendar" title="Zoroastrian calendar">Zoroastrian</a></li></ul></li> <li><a href="/wiki/Irish_calendar" title="Irish calendar">Irish</a> <ul><li>Gaelic</li></ul></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a> <ul><li><a href="/wiki/Fasli_calendar" title="Fasli calendar">Fasli</a></li> <li><a href="/wiki/Tabular_Islamic_calendar" title="Tabular Islamic calendar">Tabular</a></li></ul></li> <li><a href="/wiki/Vira_Nirvana_Samvat" title="Vira Nirvana Samvat">Jain</a></li> <li><a href="/wiki/Japanese_calendar" title="Japanese calendar">Japanese</a></li> <li><a href="/wiki/Javanese_calendar" title="Javanese calendar">Javanese</a></li> <li><a href="/wiki/Korean_calendar" title="Korean calendar">Korean</a> <ul><li><a href="/wiki/Juche_calendar" title="Juche calendar">Juche</a></li></ul></li> <li><a href="/wiki/Kurdish_calendar" title="Kurdish calendar">Kurdish</a></li> <li><a href="/wiki/Lithuanian_calendar" title="Lithuanian calendar">Lithuanian</a></li> <li><a href="/wiki/Tirhuta_Panchang" title="Tirhuta Panchang">Maithili</a></li> <li><a href="/wiki/Malayalam_calendar" title="Malayalam calendar">Malayalam</a></li> <li><a href="/wiki/Mandaean_calendar" title="Mandaean calendar">Mandaean</a></li> <li><a href="/wiki/Meitei_calendar" title="Meitei calendar">Manipuri (Meitei)</a></li> <li><a href="/wiki/Melanau_calendar" title="Melanau calendar">Melanau</a></li> <li><a href="/wiki/Mongolian_calendar" title="Mongolian calendar">Mongolian</a></li> <li>Nepal <ul><li><a href="/wiki/Nepal_Sambat" title="Nepal Sambat">Nepal Sambat</a></li> <li><a href="/wiki/Vikram_Samvat" title="Vikram Samvat">Vikram Samvat</a></li> <li><a href="/wiki/Yele_Sambat" title="Yele Sambat">Yele Sambat</a></li></ul></li> <li><a href="/wiki/Nisga%27a#Nisga’a_calendar/life" title="Nisga'a">Nisg̱a'a</a></li> <li><a href="/wiki/Odia_calendar" title="Odia calendar">Odia</a></li> <li><a href="/wiki/Punjabi_calendar" title="Punjabi calendar">Punjabi</a> <ul><li><a href="/wiki/Nanakshahi_calendar" title="Nanakshahi calendar">Nanakshahi</a></li></ul></li> <li><a href="/wiki/Romanian_calendar" title="Romanian calendar">Romanian</a></li> <li><a href="/wiki/Shona_calendar" title="Shona calendar">Shona</a></li> <li><a href="/wiki/Somali_calendar" title="Somali calendar">Somali</a></li> <li><a href="/wiki/Sotho_calendar" title="Sotho calendar">Sesotho</a></li> <li><a href="/wiki/Slavic_calendar" title="Slavic calendar">Slavic</a> <ul><li><a href="/wiki/Slavic_Native_Faith%27s_calendars_and_holidays" title="Slavic Native Faith's calendars and holidays">Slavic Native Faith</a></li> <li><a href="/wiki/Macedonian_months" title="Macedonian months">Macedonian</a></li></ul></li> <li><a href="/wiki/Tamil_calendar" title="Tamil calendar">Tamil</a></li> <li><a href="/wiki/Thai_calendar" title="Thai calendar">Thai</a> <ul><li><a href="/wiki/Thai_lunar_calendar" title="Thai lunar calendar">lunar</a></li> <li><a href="/wiki/Thai_solar_calendar" title="Thai solar calendar">solar</a></li></ul></li> <li><a href="/wiki/Tibetan_calendar" title="Tibetan calendar">Tibetan</a></li> <li><a href="/wiki/Tripuri_calendar" title="Tripuri calendar">Tripuri</a></li> <li><a href="/wiki/Tulu_calendar" title="Tulu calendar">Tulu</a></li> <li><a href="/wiki/Vietnamese_calendar" title="Vietnamese calendar">Vietnamese</a></li> <li><a href="/wiki/Wheel_of_the_Year" title="Wheel of the Year">Wicca</a></li> <li><a href="/wiki/Xhosa_calendar" title="Xhosa calendar">Xhosa</a></li> <li><a href="/wiki/Yoruba_calendar" title="Yoruba calendar">Yoruba</a></li> <li><a href="/wiki/Zulu_calendar" title="Zulu calendar">Zulu</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;">Types</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Runic_calendar" title="Runic calendar">Runic</a></li> <li><a href="/wiki/Mesoamerican_calendars" title="Mesoamerican calendars">Mesoamerican</a> <ul><li><a href="/wiki/Mesoamerican_Long_Count_calendar" title="Mesoamerican Long Count calendar">Long Count</a></li> <li><a href="/wiki/Calendar_round" class="mw-redirect" title="Calendar round">Calendar round</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;">Christian variants</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Coptic_calendar" title="Coptic calendar">Coptic</a></li> <li><a href="/wiki/Ethiopian_calendar" title="Ethiopian calendar">Ethiopian and Eritrean</a></li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Julian</a> <ul><li><a href="/wiki/Revised_Julian_calendar" title="Revised Julian calendar">Revised</a></li></ul></li> <li><a href="/wiki/Liturgical_year" title="Liturgical year">Liturgical year</a> <ul><li><a href="/wiki/Eastern_Orthodox_liturgical_calendar" title="Eastern Orthodox liturgical calendar">Eastern Orthodox</a></li></ul></li> <li><a href="/wiki/Calendar_of_saints" title="Calendar of saints">Saints</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Historical</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Pre-Islamic_Arabian_calendar" title="Pre-Islamic Arabian calendar">Arabian</a></li> <li><a href="/wiki/Attic_calendar" title="Attic calendar">Attic</a></li> <li><a href="/wiki/Aztec_calendar" title="Aztec calendar">Aztec</a> <ul><li><a href="/wiki/T%C5%8Dnalp%C5%8Dhualli" title="Tōnalpōhualli">Tōnalpōhualli</a></li> <li><a href="/wiki/Xiuhp%C5%8Dhualli" title="Xiuhpōhualli">Xiuhpōhualli</a></li></ul></li> <li><a href="/wiki/Babylonian_calendar" title="Babylonian calendar">Babylonian</a></li> <li><a href="/wiki/Bulgar_calendar" title="Bulgar calendar">Bulgar</a></li> <li><a href="/wiki/Byzantine_calendar" title="Byzantine calendar">Byzantine</a></li> <li><a href="/wiki/Cappadocian_calendar" title="Cappadocian calendar">Cappadocian</a></li> <li><a href="/wiki/Celtic_calendar" title="Celtic calendar">Celtic</a></li> <li><a href="/wiki/Cham_calendar" title="Cham calendar">Cham</a></li> <li><a href="/wiki/Chula_Sakarat" title="Chula Sakarat">Culāsakaraj</a></li> <li><a href="/wiki/Coligny_calendar" title="Coligny calendar">Coligny</a></li> <li><a href="/wiki/Egyptian_calendar" title="Egyptian calendar">Egyptian</a></li> <li><a href="/wiki/Enoch_calendar" title="Enoch calendar">Enoch</a></li> <li><a href="/wiki/Florentine_calendar" title="Florentine calendar">Florentine</a></li> <li><a href="/wiki/French_Republican_calendar" title="French Republican calendar">French Republican</a></li> <li><a href="/wiki/Germanic_calendar" class="mw-redirect" title="Germanic calendar">Germanic</a></li> <li><a href="/wiki/Ancient_Greek_calendars" title="Ancient Greek calendars">Greek</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu</a></li> <li><a href="/wiki/Inca_calendar" class="mw-redirect" title="Inca calendar">Inca</a></li> <li><a href="/wiki/Ancient_Macedonian_calendar" title="Ancient Macedonian calendar">Macedonian</a></li> <li><a href="/wiki/Maya_calendar" title="Maya calendar">Maya</a> <ul><li><a href="/wiki/Haab%CA%BC" title="Haabʼ">Haabʼ</a></li> <li><a href="/wiki/Tzolk%CA%BCin" title="Tzolkʼin">Tzolkʼin</a></li></ul></li> <li><a href="/wiki/Muisca_calendar" title="Muisca calendar">Muisca</a></li> <li><a href="/wiki/Pentecontad_calendar" title="Pentecontad calendar">Pentecontad</a></li> <li><a href="/wiki/Pisan_calendar" title="Pisan calendar">Pisan</a></li> <li><a href="/wiki/Qumran_calendrical_texts" title="Qumran calendrical texts">Qumran</a></li> <li><a href="/wiki/Rapa_Nui_calendar" title="Rapa Nui calendar">Rapa Nui</a></li> <li><a href="/wiki/Roman_calendar" title="Roman calendar">Roman</a></li> <li><a href="/wiki/Rumi_calendar" title="Rumi calendar"><i>Rumi</i></a></li> <li><a href="/wiki/Sexagenary_cycle" title="Sexagenary cycle">Sexagenary</a></li> <li><a href="/wiki/Soviet_calendar" title="Soviet calendar">Soviet</a></li> <li><a href="/wiki/Swedish_calendar" title="Swedish calendar">Swedish</a></li> <li><a href="/wiki/2002_renaming_of_Turkmen_months_and_days_of_week" title="2002 renaming of Turkmen months and days of week">Turkmen</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">By specialty</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Holocene_calendar" title="Holocene calendar">Holocene</a> <ul><li>anthropological</li></ul></li> <li><a href="/wiki/Proleptic_Gregorian_calendar" title="Proleptic Gregorian calendar">Proleptic Gregorian</a> / <a href="/wiki/Proleptic_Julian_calendar" title="Proleptic Julian calendar">Proleptic Julian</a> <ul><li>historiographical</li></ul></li> <li><a href="/wiki/Darian_calendar" title="Darian calendar">Darian</a> <ul><li>Martian</li></ul></li> <li><a href="/wiki/Dreamspell" title="Dreamspell">Dreamspell</a> <ul><li>New Age</li></ul></li> <li><a href="/wiki/Discordian_calendar" title="Discordian calendar">Discordian</a></li> <li><a href="/wiki/%27Pataphysics#Pataphysical_calendar" title="'Pataphysics">'Pataphysical</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a class="mw-selflink selflink">Reform proposals</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Hanke%E2%80%93Henry_Permanent_Calendar" title="Hanke–Henry Permanent Calendar">Hanke–Henry Permanent</a></li> <li><a href="/wiki/International_Fixed_Calendar" title="International Fixed Calendar">International Fixed</a></li> <li><a href="/wiki/Pax_Calendar" title="Pax Calendar">Pax</a></li> <li><a href="/wiki/Positivist_calendar" title="Positivist calendar">Positivist</a></li> <li><a href="/wiki/Symmetry454" title="Symmetry454">Symmetry454</a></li> <li><a href="/wiki/World_Calendar" title="World Calendar">World</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Displays and<br />applications</div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Calendaring_software" class="mw-redirect" title="Calendaring software">Electronic</a></li> <li><a href="/wiki/Perpetual_calendar" title="Perpetual calendar">Perpetual</a></li> <li><a href="/wiki/Calendar_(stationery)" title="Calendar (stationery)">Wall</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Year naming<br />and numbering</div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;">Terminology</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Calendar_era" title="Calendar era">Era</a></li> <li><a href="/wiki/Epoch" title="Epoch">Epoch</a></li> <li><a href="/wiki/Leap_year" title="Leap year">Leap year</a></li> <li><a href="/wiki/New_Year" title="New Year">New Year</a></li> <li><a href="/wiki/Regnal_name" title="Regnal name">Regnal name</a></li> <li><a href="/wiki/Regnal_year" title="Regnal year">Regnal year</a></li> <li><a href="/wiki/Year_zero" title="Year zero">Year zero</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;font-weight:normal;">Systems</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ab_urbe_condita" title="Ab urbe condita">Ab urbe condita</a></li> <li><a href="/wiki/Anka_year" title="Anka year">Anka year</a></li> <li><a href="/wiki/Anno_Domini" title="Anno Domini">Anno Domini</a>/<a href="/wiki/Common_Era" title="Common Era">Common Era</a></li> <li><a href="/wiki/Anno_Lucis" title="Anno Lucis">Anno Lucis</a></li> <li><a href="/wiki/Era_of_the_Martyrs" title="Era of the Martyrs">Anno Martyrum</a></li> <li><a href="/wiki/Anno_Mundi" title="Anno Mundi">Anno Mundi</a></li> <li><a href="/wiki/Eponym_dating_system" title="Eponym dating system">Assyrian</a></li> <li><a href="/wiki/Before_Present" title="Before Present">Before Present</a></li> <li><a href="/wiki/Chinese_era_name" title="Chinese era name">Chinese Imperial</a></li> <li><a href="/wiki/Republic_of_China_calendar" title="Republic of China calendar">Chinese Minguo</a></li> <li><a href="/wiki/Regnal_years_of_English_and_British_monarchs" title="Regnal years of English and British monarchs">English and British regnal year</a></li> <li><a href="/wiki/Hijri_year" title="Hijri year">Hijri year</a></li> <li><a href="/wiki/Holocene_calendar" title="Holocene calendar">Human (Holocene)</a></li> <li><a href="/wiki/Japanese_era_name" title="Japanese era name">Japanese</a></li> <li><a href="/wiki/Korean_era_name" title="Korean era name">Korean</a></li> <li><a href="/wiki/Nirayana_system" title="Nirayana system">Nirayana system</a></li> <li><a href="/wiki/Seleucid_era" title="Seleucid era">Seleucid</a></li> <li><a href="/wiki/Spanish_era" title="Spanish era">Spanish</a></li> <li><a href="/wiki/Yuga" title="Yuga">Yugas</a> <ul><li><a href="/wiki/Satya_Yuga" title="Satya Yuga">Satya</a></li> <li><a href="/wiki/Treta_Yuga" title="Treta Yuga">Treta</a></li> <li><a href="/wiki/Dvapara_Yuga" title="Dvapara Yuga">Dvapara</a></li> <li><a href="/wiki/Kali_Yuga" title="Kali Yuga">Kali</a></li></ul></li> <li><a href="/wiki/Vietnamese_era_name" title="Vietnamese era name">Vietnamese</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fictional</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Discworld_(world)#Calendar" title="Discworld (world)">Discworld</a> (<i><a href="/wiki/Discworld" title="Discworld">Discworld</a></i>)</li> <li><a href="/wiki/Flanaess#Calendar" class="mw-redirect" title="Flanaess">Greyhawk</a> (<i><a href="/wiki/Dungeons_%26_Dragons" title="Dungeons & Dragons">Dungeons & Dragons</a></i>)</li> <li><a href="/wiki/Middle-earth_calendar" class="mw-redirect" title="Middle-earth calendar">Middle-earth</a> (<i><a href="/wiki/The_Lord_of_the_Rings" title="The Lord of the Rings">The Lord of the Rings</a></i>)</li> <li><a href="/wiki/Stardate" title="Stardate">Stardate</a> (<i><a href="/wiki/Star_Trek" title="Star Trek">Star Trek</a></i>)</li></ul> </div></td></tr><tr><td class="navbox-abovebelow hlist" colspan="2"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="List-Class article"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/16px-Symbol_list_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/23px-Symbol_list_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/31px-Symbol_list_class.svg.png 2x" data-file-width="180" data-file-height="185" 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