Extract response format

{
  "result_type": "extract",
  "data": { "invoice_number": "INV-1042", "total": null },
  "fields": [
    {
      "path": "/invoice_number",
      "value": "INV-1042",
      "status": "found",
      "confidence": null,
      "citations": [
        {
          "location": { "kind": "page_region", "page": 1, "polygons": [] },
          "source_text": "Invoice INV-1042"
        }
      ]
    },
    {
      "path": "/total",
      "value": null,
      "status": "not_found",
      "citations": []
    }
  ],
  "schema_id": null,
  "schema_version": null,
  "units": 1,
  "warnings": []
}