bm-1.0.x-dev/config/schema/bm.schema.yml

# Field storage.
field.storage_settings.bm_book_button:
  type: mapping
  label: Example storage settings
  mapping:
    foo:
      type: string
      label: Foo

# Field instance.
field.field_settings.bm_book_button:
  type: mapping
  label: Example field settings
  mapping:
    bar:
      type: string
      label: Bar

# Default value.
field.value.bm_book_button:
  type: mapping
  label: Default value
  mapping:
    value_1:
      type: string
      label: Value 1

# Field widget.
# field.widget.settings.bm_book_button:
#   type: mapping
#   label: Example widget settings
#   mapping:
#     foo:
#       type: string
#       label: Foo

# Field formatter.
field.formatter.settings.bm_book_button_default:
  type: mapping
  label: Example formatter settings
  mapping:
    foo:
      type: string
      label: Foo