"sdfData": {
  "Coordinate" : {
    "type": "number", "unit": "m"
  },
  "X-Coordinate" : {
    "sdfRef" : "#/sdfData/Coordinate",
    "description":
"Distance from the base of the Thing along the X axis."
  },
  "Non-neg-X-Coordinate" : {
    "sdfRef": "#/sdfData/X-Coordinate",
    "minimum": 0
  }
}