{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "pd_a": { "type": "number" },
    "pd_b": { "type": "number" },
    "pd_t": { "type": "number" },
    "pd_iso_a": {"type": "number" },
    "pd_iso_b": {"type": "number" },
    "final_pd": {"type": "number" },
    "grade": {"type": "string"}
  },
  "required": ["final_pd", "grade", "pd_a", "pd_b", "pd_t", "pd_iso_a", "pd_iso_b"],
  "additionalProperties": false
}