book-2.0.x-dev/config/schema/book.schema.yml

# Schema for the configuration files of the book module.

book.settings:
  type: config_object
  label: 'Book settings'
  constraints:
    FullyValidatable: ~
  mapping:
    allowed_types:
      type: sequence
      label: 'Content types allowed in book outlines'
      sequence:
        type: string
        label: 'Content type'
        constraints:
          EntityBundleExists: node
    child_type:
      type: string
      label: 'Content type for child pages'
      constraints:
        EntityBundleExists: node
        ExistsIn:
          selector: '%parent.allowed_types'
          which: values
          message: "The content type for the <em>Add child page</em> link must be one of those selected as an allowed book outline type."
    book_sort:
      type: string
      label: 'Sort order'
      constraints:
        Choice:
          - weight
          - title

block.settings.book_navigation:
  type: block_settings
  label: 'Book navigation block'
  mapping:
    block_mode:
      type: string
      label: 'Block display mode'
      constraints:
        Choice:
          - 'all pages'
          - 'book pages'
          - 'primary book page'
          - 'child book pages'
    show_top_item:
      type: boolean
      label: 'Show top level item'
    use_top_level_title:
      type: boolean
      label: 'Use the top-level page title as block title'