{
  "name": "Calibration card: Gregorian calendar",
  "desc": "The values in the Calibration card at the top of the page, one field per row, with the source of each value.",
  "lic": "CC BY 4.0",
  "lic_url": "https://creativecommons.org/licenses/by/4.0/",
  "by": "The Yardstick Almanac",
  "url": "https://theyardstickalmanac.com/calendars/gregorian-leap-year-rule/",
  "from": [
    "Gregorian and Julian leap-year rules, Explanatory Supplement to the Astronomical Almanac, ch. 15, sec. 15.4.2 and 15.3.5",
    "Calendar (New Style) Act 1750, sections 1–2, legislation.gov.uk"
  ],
  "how": "Compiled by The Yardstick Almanac from the data listed",
  "data_by": [
    "Explanatory Supplement to the Astronomical Almanac, ch. 15, and Calendar (New Style) Act 1750; values computed 2026-11-01, CC BY 4.0"
  ]
}