core/homeassistant/components/soundtouch/services.yaml

play_everywhere:
  description: Play on all Bose Soundtouch devices.
  fields:
    master:
      description: Name of the master entity that will coordinate the grouping. Platform dependent. It is a shortcut for creating a multi-room zone with all devices
      example: 'media_player.soundtouch_home'

create_zone:
  description: Create a Sountouch multi-room zone.
  fields:
    master:
      description: Name of the master entity that will coordinate the multi-room zone. Platform dependent.
      example: 'media_player.soundtouch_home'
    slaves:
      description: Name of slaves entities to add to the new zone.
      example: 'media_player.soundtouch_bedroom'

add_zone_slave:
  description: Add a slave to a Sountouch multi-room zone.
  fields:
    master:
      description: Name of the master entity that is coordinating the multi-room zone. Platform dependent.
      example: 'media_player.soundtouch_home'
    slaves:
      description: Name of slaves entities to add to the existing zone.
      example: 'media_player.soundtouch_bedroom'

remove_zone_slave:
  description: Remove a slave from the Sounttouch multi-room zone.
  fields:
    master:
      description: Name of the master entity that is coordinating the multi-room zone. Platform dependent.
      example: 'media_player.soundtouch_home'
    slaves:
      description: Name of slaves entities to remove from the existing zone.
      example: 'media_player.soundtouch_bedroom'