form.json

{
  "label": "Subform Top",
  "sections": [
    {
      "label": "Subform Top",
      "fields": [
        {
          "id": "121",
          "type": "text",
          "required": true,
          "label": "top name",
          "labelPosition": "left",
          "calculations": {
            "value": "{{field-122 key=value subform=field-123}}"
          }
        },
        {
          "id": "122",
          "type": "subform",
          "label": "Subform Validation",
          "labelPosition": "above",
          "required": true,
          "definition": {
            "label": "Subform Inner",
            "sections": [
              {
                "label": "Subform Inner",
                "fields": [
                  {
                    "id": "123",
                    "type": "text",
                    "required": true,
                    "label": "inner Name",
                    "labelPosition": "left"
                  }
                ]
              }
            ]
          }
        }
      ]
    }
  ]
}