{
  "$schema": "http://json-schema.org/draft-04/schema",
  "$id": "https://example.com/product.schema.json",
  "title": "Form",
  "description": "A form",
  "type": "object",
  "properties": {
    "form_type": {
      "description": "",
      "type": "string"
    },
    "start_year": {
      "description": "",
      "type": "integer",
      "optional": "true"
    },
    "end_year": {
      "description": "",
      "type": "integer",
      "required": "false"
    },
    "sections": {
      "description": "",
      "type": "object",
      "patternProperties": {
        "^[0-9]+$": {
          "description": "",
          "type": "string"
        },
        "label": {
          "description": "",
          "type": "string"  
        },
        "subsections": {
          "type": "object"
        }
      }
    }
  }
}