{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.hebrew-calendar","code":"thing-q44722","url":"https://ver.cy/models/thing/q44722/","name":"Hebrew calendar","alternateNames":["Rosh Chodesh"],"kind":"thing","status":"published","version":"0.1.0-research.1","language":"en","classifiers":{"family":"Thing Registry","category":"Information and virtual systems","entryKind":"thing","plane":"INF","domain":["INF.KNW"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"The Hebrew calendar is the lunisolar calendar of rabbinic Judaism: months follow a conventional mean lunar conjunction (the molad), years are kept near the solar seasons by inserting a second Adar in seven years of a nineteen-year cycle, and 1 Tishrei is further constrained by weekday postponement rules (deḥiyyot), with years numbered from a conventional era of creation (Anno Mundi).","purpose":"Enable an AI agent to identify a Hebrew calendar regime, assess whether a date or calendar calculation is valid and sufficiently specified, and determine which conversions or scheduling actions are justified.","scope":{"in":["Identification of the calendar tradition, governing rules, and historical applicability","Year numbering, leap-year status, month sequence, and variable year lengths","Hebrew date expressions, month-name aliases, and date validity","Day boundaries and the location and time assumptions required to assign a date","Conversion to other calendars and scheduling of Hebrew-date recurrences","Calendar-derived observance dates and dependencies on community conventions"],"out":["Religious obligations, permissions, and authoritative rulings about observance","Liturgical texts and synagogue service procedures","General astronomy, solar-position calculation, and lunar ephemerides","Civil time-zone administration and the internal rules of other calendars","Personal life events and historical events dated using the calendar"],"boundaries":[]},"distinguishingFeatures":["Test whether the rules coordinate lunar months with the solar year through intercalation; a purely lunar calendar without this adjustment is a different system.","For the standard fixed Hebrew calendar, test whether leap years follow the specified seven positions in a 19-year cycle and introduce an additional Adar month.","Test whether the system distinguishes the Tishrei year-number transition from month numbering that begins with Nisan.","Test whether date assignment accounts for the Hebrew day's evening boundary rather than assuming a midnight rollover.","Test whether fixed-calendar calculations account for postponement rules and variable Cheshvan and Kislev lengths; alternating month lengths alone do not identify a valid Hebrew year."],"structure":{"bundles":[{"id":"calendar-regime-and-authority","name":"Calendar Regime and Authority","description":"Identify which Hebrew calendar rules a representation or calculation claims to follow.","layers":[{"id":"fixed-and-historical-reckoning","name":"Fixed and Historical Reckoning","description":"Separate the standard fixed calendar from historical or otherwise distinct methods of establishing dates.","findings":[{"id":"applicable-hebrew-calendar-regime","name":"Applicable Hebrew Calendar Regime","description":"Record the intended regime and distinguish reconstruction of an attested date from retrospective application of fixed rules.","questions":[{"text":"Does this use the standard fixed rabbinic calendar, an identified observational practice, or another specified Hebrew calendar tradition?","id":"applicable-hebrew-calendar-regime-q01","kind":"definition"},{"text":"What evidence supports applying that regime to the community and period being represented?","id":"applicable-hebrew-calendar-regime-q02","kind":"provenance"}]}]},{"id":"rule-sources-and-calculation-authority","name":"Rule Sources and Calculation Authority","description":"Establish which sources and implementations support the calendar's operational rules.","findings":[{"id":"traceable-calendar-rules","name":"Traceable Calendar Rules","description":"Associate leap-year, molad, postponement, and month-length rules with identifiable sources and implementation conventions.","questions":[{"text":"Which source specifies the leap-year cycle, molad arithmetic, and postponement rules used here?","id":"traceable-calendar-rules-q01","kind":"provenance"},{"text":"When a calendar table and an implementation disagree, what evidence or designated authority determines which result the agent may use?","id":"traceable-calendar-rules-q02","kind":"action"}]}]}]},{"id":"hebrew-year-and-month-structure","name":"Hebrew Year and Month Structure","description":"Represent the interdependent rules that determine year identity, intercalation, month order, and valid dates.","layers":[{"id":"year-numbering-and-intercalation","name":"Year Numbering and Intercalation","description":"Resolve year expressions and establish the applicable leap-year status.","findings":[{"id":"resolved-year-and-cycle-position","name":"Resolved Year and Cycle Position","description":"Record the era, full year number, Tishrei transition, and cycle convention needed to determine intercalation.","questions":[{"text":"What full year and era does the expression denote, particularly when thousands are omitted?","id":"resolved-year-and-cycle-position-q01","kind":"definition"},{"text":"Under the selected fixed-calendar convention, what is the year's position in the 19-year cycle and is it common or leap?","id":"resolved-year-and-cycle-position-q02","kind":"measurement"}]}]},{"id":"month-identity-and-year-shape","name":"Month Identity and Year Shape","description":"Resolve month names and derive the valid sequence and lengths for a particular year.","findings":[{"id":"valid-month-and-day-combination","name":"Valid Month and Day Combination","description":"Distinguish Nisan-based numbering from Tishrei-based ordering, resolve Adar identity, and check dates against year-specific month lengths.","questions":[{"text":"Which named month does the supplied label or number identify, and does an unqualified Adar require clarification in this year?","id":"valid-month-and-day-combination-q01","kind":"definition"},{"text":"Do the calculated year length and Cheshvan and Kislev lengths permit this month-and-day combination?","id":"valid-month-and-day-combination-q02","kind":"measurement"}]}]}]},{"id":"day-boundaries-and-date-conversion","name":"Day Boundaries and Date Conversion","description":"Control how Hebrew dates relate to local evenings, civil dates, and precise instants.","layers":[{"id":"local-evening-boundary","name":"Local Evening Boundary","description":"Capture the geographic and interpretive context required near the transition between Hebrew dates.","findings":[{"id":"resolved-or-ambiguous-day-assignment","name":"Resolved or Ambiguous Day Assignment","description":"Record location and boundary conventions, including whether twilight leaves a date assignment unresolved for the intended use.","questions":[{"text":"Which location, time zone, and solar-boundary calculation apply to this instant?","id":"resolved-or-ambiguous-day-assignment-q01","kind":"measurement"},{"text":"Does the instant fall in a twilight interval or exceptional geographic situation for which the intended use requires a specified convention?","id":"resolved-or-ambiguous-day-assignment-q02","kind":"boundary"}]}]},{"id":"conversion-semantics","name":"Conversion Semantics","description":"Distinguish conversion of date labels from conversion of timed events and historical date assertions.","findings":[{"id":"explicit-conversion-contract","name":"Explicit Conversion Contract","description":"Record the input's precision, the other calendar's identity, and whether the result denotes a conventional date correspondence or an interval of instants.","questions":[{"text":"Is the input a Hebrew date label, a local civil date, or a timestamp, and is the other calendar Gregorian, Julian, or explicitly something else?","id":"explicit-conversion-contract-q01","kind":"definition"},{"text":"May the agent return one corresponding date, or must it return an interval or alternatives because time, location, or historical convention is missing?","id":"explicit-conversion-contract-q02","kind":"action"}]}]}]},{"id":"hebrew-date-scheduling-and-observance-interfaces","name":"Hebrew-Date Scheduling and Observance Interfaces","description":"Support recurring dates and calendar-derived observance schedules while identifying conventions that require external authority.","layers":[{"id":"adar-and-missing-day-recurrence","name":"Adar and Missing-Day Recurrence","description":"Make recurrence policies explicit when the target year differs structurally from the original year.","findings":[{"id":"authorized-hebrew-anniversary-policy","name":"Authorized Hebrew Anniversary Policy","description":"Record the purpose and governing policy for moving an anniversary between common and leap years or into a month lacking the original day.","questions":[{"text":"For this recurrence's purpose, which Adar is used when moving between common and leap years, and who or what supplies that policy?","id":"authorized-hebrew-anniversary-policy-q01","kind":"provenance"},{"text":"If the original day does not exist in the target month, should the agent apply a specified adjustment, omit the occurrence, or leave it unresolved?","id":"authorized-hebrew-anniversary-policy-q02","kind":"action"}]}]},{"id":"observance-date-conventions","name":"Observance Date Conventions","description":"Separate nominal Hebrew dates from scheduled observance dates and from religious instructions about those observances.","findings":[{"id":"calendar-derived-observance-schedule","name":"Calendar-Derived Observance Schedule","description":"Associate observance-date calculations with the applicable community, Israel or diaspora convention, and any sourced date-adjustment rule.","questions":[{"text":"Which community and Israel or diaspora convention govern the requested observance schedule?","id":"calendar-derived-observance-schedule-q01","kind":"definition"},{"text":"Is the requested result a nominal calendar date or an adjusted observance date, and which sourced rule permits any adjustment?","id":"calendar-derived-observance-schedule-q02","kind":"boundary"}]}]}]},{"id":"evidence-and-external-alignment","name":"Evidence and external alignment","description":"What the world already says about this thing, gathered so the model can be checked against it.","layers":[{"id":"reported-evidence","name":"Reported evidence","description":"Findings from the breadth pass, kept separate from the structural claims.","findings":[{"id":"evidence-kinds","name":"Kinds and varieties","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these kinds and varieties hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-kinds-q01","kind":"provenance"}]},{"id":"evidence-identifiers","name":"Identifiers and schemes","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these identifiers and schemes hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-identifiers-q01","kind":"provenance"}]},{"id":"evidence-standards-and-regulation","name":"Standards and regulation","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these standards and regulation hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-standards-and-regulation-q01","kind":"provenance"}]},{"id":"evidence-real-world-use","name":"Real-world use","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these real-world use hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-real-world-use-q01","kind":"provenance"}]},{"id":"evidence-measurements","name":"Typical measurements","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these typical measurements hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-measurements-q01","kind":"provenance"}]},{"id":"evidence-failure-modes-and-hazards","name":"Failure modes and hazards","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these failure modes and hazards hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-failure-modes-and-hazards-q01","kind":"provenance"}]},{"id":"evidence-regional-variation","name":"Regional variation","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these regional variation hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-regional-variation-q01","kind":"provenance"}]},{"id":"evidence-neighbours","name":"Neighbouring kinds and how to tell them apart","description":"Reported by the breadth pass; each item needs checking against its source before it becomes normative.","questions":[{"text":"Which of these neighbouring kinds and how to tell them apart hold for the sense of Hebrew calendar this model covers, and on what evidence?","id":"evidence-neighbours-q01","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Convert dates between the Hebrew and civil calendars using the published rules.","Show festival and Sabbath dates with the location and conventions used."],"mustNot":["Give a festival or fast date from an unchecked calculation for religious observance.","Ignore differences between Israel and the diaspora for festival days.","Schedule events in ways that exclude observant people without saying so.","Present rabbinic calendar rules inaccurately."],"requiresHuman":["Fixing dates for communal religious observance."]},"ethics":{"considerations":["The calendar orders religious life; mistakes can lead people to break observance.","Respecting it in scheduling is part of including Jewish people."],"affectedParties":["Jewish communities","Scheduling users"]},"owners":{"steward":"Rabbinic tradition holds its rules; communities and their rabbis decide local practice.","roles":[],"masterSystems":[]},"relations":[{"target":"Q194235","type":"parent","note":"registry parent class"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.hebrew-calendar","Wikidata: Q44722 (https://www.wikidata.org/wiki/Q44722)"]},"properties":{"applicability":"not-applicable","items":["Calendar regime: Standard fixed rabbinic calendar; historically attested observational regime; other explicitly identified tradition; unresolved","Rule authority and applicability: Relationship to an identified rule source, community or authority, and period of applicability","Hebrew year and era: Integer year with an explicit era and policy for omitted thousands","Metonic cycle position: Position 1-19 under an explicitly stated fixed-calendar indexing convention","Year structure: Common or leap; deficient, regular, or complete; unresolved","Month identity: Named Hebrew month, distinguishing Adar in a common year from Adar I and Adar II in a leap year","Day-boundary context: Relationship to location, time zone, solar-boundary method, and treatment of twilight","Date resolution state: Valid and resolved; invalid; incomplete; convention-dependent; boundary-ambiguous"]},"recognition":{"applicability":"not-applicable","items":[]},"capabilities":{"applicability":"required","items":["Validate a Hebrew date against its identified calendar regime and year structure.","Normalize Hebrew-script and transliterated date expressions while retaining unresolved ambiguity.","Convert dates or instants with explicit calendar, location, and day-boundary assumptions.","Compute month sequences and calendar-derived dates using an identified rule set.","Schedule Hebrew-date recurrences using an explicit Adar and missing-day policy.","Compare competing date assignments and explain which assumptions cause the difference."]},"hazards":{"applicability":"required","items":["Ignoring the sunset boundary or location can assign an event to the wrong Hebrew date.","Mishandling leap months or postponement rules can produce incorrect conversions and recurring anniversaries.","Assuming identical holiday schedules in Israel and the diaspora can cause missed observances or scheduling conflicts."]},"interfaces":{"applicability":"not-applicable","items":[]},"context":{"applicability":"required","items":["The Hebrew calendar is used to determine Jewish holidays, religious observances and commemorative dates.","It appears in religious communities, historical records and scheduling systems that display or convert Hebrew dates.","Scheduling observances requires attention to the local sunset boundary and differences between observance in Israel and the diaspora."]}},"sources":[{"title":"Hebrew calendar - Wikipedia (Wikimedia Foundation)","url":"https://en.wikipedia.org/wiki/Hebrew_calendar","note":"Structure of the lunisolar year, month names, 19-year intercalary cycle, postponement rules, Anno Mundi epoch, and the distinction between calculated and observational practice."},{"title":"Calendrical Calculations - Nachum Dershowitz and Edward M. Reingold, Cambridge University Press","url":"","note":"Canonical computational statement of molad arithmetic, year-length classes, conversion to and from the Gregorian calendar, and the mean lunation of 29 days 12 hours 793 chalakim."},{"title":"Mishneh Torah, Hilchot Kiddush HaChodesh - Moses Maimonides (standard printed and Sefaria texts)","url":"https://www.sefaria.org/Mishneh_Torah%2C_Sanctification_of_the_New_Month","note":"Classical rabbinic formulation of sanctification of the month, intercalation, and the calculated calendar's mean-motion parameters."},{"title":"Unicode Technical Standard #35 (LDML) - Unicode Consortium","url":"https://www.unicode.org/reports/tr35/","note":"Machine identifier hebrew / BCP 47 u-ca-hebrew used in locale data, ICU, and software calendars."},{"title":"Wikidata item Q44722: Hebrew calendar","url":"https://www.wikidata.org/wiki/Q44722","note":"identity and sense of the item"}],"openQuestions":["Does the registry intend this entry to own only the standard fixed rabbinic calendar or also historical and other Hebrew calendar regimes?","Which authoritative sources and independent reference calculations should establish the supported fixed-calendar rules and conversion range?","For which historical periods can date assignments be supported as attested practice, and where must results be labeled retrospective or uncertain?","Which conventions should govern twilight, high-latitude conditions, and geographic date-boundary disputes for the intended applications?","Which recurrence and observance-date policies may this model apply directly, and which require a linked community or religious-authority model?"],"resources":{"spec":"/models/things/publications/thing-q44722/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q44722/spec.json"],"providers":["Codex","Grok"],"researchStatus":"unreviewed","generatedAt":"2026-09-07T10:19:44Z","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":"not-applicable","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"not-applicable","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:31+00:00: completeness 1.00; sense: Wikidata description; 4 live sources; review by codex: pass","interaction.properties":"Plane INF: no invented physical properties.","interaction.interfaces":"No single technical standard, law or official classification universally governs the Hebrew calendar in this general sense.","interaction.recognition":"The calendar is an abstract system of date rules and has no intrinsic visual appearance."},"score":1.0}}