core/homeassistant/components/soundtouch/services.yaml

play_everywhere:
  fields:
    master:
      required: true
      selector:
        entity:
          integration: soundtouch
          domain: media_player

create_zone:
  fields:
    master:
      required: true
      selector:
        entity:
          integration: soundtouch
          domain: media_player
    slaves:
      required: true
      selector:
        entity:
          multiple: true
          integration: soundtouch
          domain: media_player

add_zone_slave:
  fields:
    master:
      required: true
      selector:
        entity:
          integration: soundtouch
          domain: media_player
    slaves:
      required: true
      selector:
        entity:
          multiple: true
          integration: soundtouch
          domain: media_player

remove_zone_slave:
  fields:
    master:
      required: true
      selector:
        entity:
          integration: soundtouch
          domain: media_player
    slaves:
      required: true
      selector:
        entity:
          multiple: true
          integration: soundtouch
          domain: media_player