{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.march-21","code":"thing-q2433","url":"https://ver.cy/models/thing/q2433/","name":"March 21","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.2","language":"en","classifiers":{"family":"Thing Registry","category":"Cross-cutting context","entryKind":"thing","plane":"XCT","domain":["XCT.TME"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"March 21, day 80 (day 81 in leap years) of the year in the Gregorian calendar, with 285 days remaining in both common and leap years. Observances on this date vary by country and tradition; it falls on or near the March equinox and is the International Day for the Elimination of Racial Discrimination and World Poetry Day.","purpose":"Let an agent handle March 21 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["The twenty-first day of March","Weekday varies by year","Observances vary by place","Julian and Gregorian dates differ by 13 days in this era"],"structure":{"bundles":[{"id":"date","name":"Date","description":"Calendar facts.","layers":[{"id":"weekday","name":"Weekday","description":"Computation.","findings":[{"id":"weekday-finding","name":"Weekday","description":"Weekday.","questions":[{"text":"On which weekday does March 21 fall in this year?","kind":"measurement"},{"text":"Is it a leap year?","kind":"boundary"}]}]},{"id":"calendar","name":"Calendar","description":"Julian or Gregorian.","findings":[{"id":"calendar-finding","name":"Calendar","description":"Calendar system.","questions":[{"text":"Is the Julian or Gregorian calendar meant?","kind":"boundary"},{"text":"What is the equivalent date in the other calendar?","kind":"measurement"}]}]}]},{"id":"observances","name":"Observances","description":"Holidays.","layers":[{"id":"holiday","name":"Holiday","description":"Public holiday.","findings":[{"id":"holiday-finding","name":"Holiday","description":"Holiday status.","questions":[{"text":"Is March 21 a public holiday or observance here?","kind":"provenance"},{"text":"Which tradition or law sets it?","kind":"provenance"}]}]},{"id":"attribution","name":"Attribution","description":"Traditions.","findings":[{"id":"attribution-finding","name":"Attribution","description":"Attributed observances.","questions":[{"text":"Which countries or communities observe something on this date, according to them?","kind":"provenance"},{"text":"Is the observance attributed rather than assumed?","kind":"boundary"}]}]}]},{"id":"history","name":"History","description":"Past events.","layers":[{"id":"events","name":"Events","description":"On this day.","findings":[{"id":"events-finding","name":"Events","description":"Historical events.","questions":[{"text":"Which notable events happened on March 21, according to reliable sources?","kind":"provenance"},{"text":"Are dates given in the same calendar?","kind":"boundary"}]}]},{"id":"anniversaries","name":"Anniversaries","description":"Recurring.","findings":[{"id":"anniversaries-finding","name":"Anniversaries","description":"Anniversaries.","questions":[{"text":"Which anniversaries fall on this date this year?","kind":"provenance"},{"text":"Which are round numbers?","kind":"measurement"}]}]}]},{"id":"planning","name":"Planning","description":"Scheduling.","layers":[{"id":"countdown","name":"Countdown","description":"Days until.","findings":[{"id":"countdown-finding","name":"Countdown","description":"Countdown.","questions":[{"text":"How many days until the next March 21?","kind":"measurement"},{"text":"From which date?","kind":"definition"}]}]},{"id":"work","name":"Work","description":"Working day.","findings":[{"id":"work-finding","name":"Work","description":"Working day.","questions":[{"text":"Is it a working day for this organisation?","kind":"provenance"},{"text":"Do deadlines move?","kind":"boundary"}]}]}]}]},"agentConduct":{"may":["Compute day-of-year and weekday for March 21 in a given year.","List observances on March 21 by country with sources, including Nowruz where it falls on that day."],"mustNot":["Assume the March equinox always falls on March 21.","Present Nowruz or other March 21 observances as universal or as tied to one nation alone.","Report on-this-day events for March 21 without a source."],"requiresHuman":["Fixing a legal deadline that depends on the equinox or a March 21 holiday."]},"ethics":{"considerations":["New year and equinox festivals around March 21 matter to many peoples across countries."],"affectedParties":["Communities celebrating Nowruz","Calendar users"]},"owners":{"steward":"Nobody owns a date; calendar and holiday authorities set observances.","roles":[],"masterSystems":[]},"relations":[{"target":"Q11187254","type":"parent","note":"registry parent class"},{"target":"March","type":"related","note":"month"},{"target":"March 20","type":"related","note":"date"},{"target":"calendar date","type":"related","note":"category"},{"target":"ISO 8601","type":"related","note":"notation"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.march-21","Wikidata: Q2433 (https://www.wikidata.org/wiki/Q2433)","ISO 8601: --03-21 recurring date"]},"properties":{"applicability":"not-applicable","items":["day of year: 80 or 81 day - common year, leap year where different","days remaining: 285 days"]},"recognition":{"applicability":"optional","items":["Written 21 March or March 21","ISO format --03-21","Observances vary by country and tradition","A date on calendars."]},"capabilities":{"applicability":"required","items":["compute its weekday in a given year","check local and international observances","find sourced historical events","schedule events"]},"hazards":{"applicability":"required","items":["Assuming observances are universal","Unsourced on-this-day events","Mixing Julian and Gregorian dates"]},"interfaces":{"applicability":"required","items":["ISO 8601","National public holiday laws"]},"context":{"applicability":"required","items":["A calendar date for scheduling, holidays and anniversaries.","the recurring calendar date","specific dated days in given years"]}},"sources":[{"title":"Wikidata item Q2433: March 21","url":"https://www.wikidata.org/wiki/Q2433","note":"identity and sense of the item"},{"title":"Wikipedia: March 21","url":"https://en.wikipedia.org/wiki/March_21","note":"general description of the item"}],"openQuestions":["Should dated days be separate entries?","How should observances be linked?","How should events be sourced?"],"resources":{"spec":"/models/things/publications/thing-q2433/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q2433/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T00:17:05Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"not-applicable","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-06T19:51:57+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass","interaction.properties":"Plane XCT: no invented physical properties."},"score":1.0}}