core/homeassistant/components/blackbird/strings.json

{
  "services": {
    "set_all_zones": {
      "description": "Sets all Blackbird zones to a single source.",
      "fields": {
        "entity_id": {
          "description": "Name of any blackbird zone.",
          "name": "Entity"
        },
        "source": {
          "description": "Name of source to switch to.",
          "name": "Source"
        }
      },
      "name": "Set all zones"
    }
  }
}