{
    "type": "object",
    "properties": {
      "club_hold_id": {
        "type": "integer",
        "description": "Internal club hold identifier"
      },
      "club_id": {
        "type": "integer",
        "description": "Internal club identifier"
      },
      "biblio_id": {
        "type": "integer",
        "description": "Internal biblio identifier"
      },
      "item_id": {
        "type": ["string", "null"],
        "description": "Internal item identifier"
      }
    }
  }