{
  "display_rule": "registered derived rationals: three decimals, nearest, half away from zero; do not infer source accuracy from display",
  "exact_numeric_encoding": "reduced rational strings where applicable; source indices/counts are not rounded before comparison",
  "limitations": [
    "Regional, homogenised temperature indices, not every station or garden",
    "Below-zero regional-minimum days are not ground-frost counts",
    "Fixed December-February winters and 1961-1990 reference-ending years",
    "Reference is equally weighted winter means, not pooled baseline days",
    "Historical comparison, not a forecast or future probability",
    "No planting, heating, health, household-cost or safety recommendation",
    "Source precision 0.1 Celsius; exact zero is not counted below zero"
  ],
  "method_version": "winter-experimental-1",
  "source_row_references": "line numbers include header; H6 workbook cell/date lineage in complete result",
  "source_units": "degrees Celsius; days with regional minimum index below zero"
}