{
  "name": "Calibration card: prime meridian",
  "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/maps/prime-meridian/",
  "from": [
    "International Meridian Conference, Protocols of the Proceedings (Washington, 1884), public domain, Final Act and sessions of October 13 and 22",
    "E. Walter Maunder, The Royal Observatory, Greenwich (1900), public domain",
    "IERS Conventions (2010), chapter 4",
    "Malys et al., Journal of Geodesy 89 (2015), abstract"
  ],
  "how": "Compiled by The Yardstick Almanac from the data listed",
  "data_by": [
    "International Meridian Conference protocols (1884), Maunder (1900), IERS Conventions (2010) ch. 4; compiled 2026-11-01, CC BY 4.0"
  ]
}