Elastic \ Opensearch life cycle management - what is the difference between read_write & open actions

Question

I want to use life cycle management, the goal is to delete messages after 14 days

What should be the action in the first stage? Open or Read_write What is the difference between the two actions?

    {
  "policy": {
    "policy_id": "delete_after14_days",
    "description": "index delete"
    "schema_version": 1,
    "error_notification": null,
    "default_state": "open",
    "states": [
      {
        "name": "hot",
        "actions": [
          {
            **"open": {}  or "read_write": {}**
          }
        ],
        "transitions": [
          {
            "state_name": "delete",
            "conditions": {
              "min_index_age": "14d"
            }
          }
        ]
      },
      {
        "name": "delete",
        "actions": [
          {
            "delete": {}
          }
        ],
        "transitions": []
      }
    ],
    "ism_template": [
      {
        "index_patterns": [
          "audit-*"
        ],
        "priority": 0
      }
    ]
  }
}