{
  "$defs": {
    "Date": {
      "description": "Civil date in simplified ISO format, like 2021-05-26",
      "format": "date",
      "title": "Date",
      "type": "string"
    }
  },
  "$id": "https://gobl.org/draft-0/cal/date",
  "$ref": "#/$defs/Date",
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}