artisan-1.x-dev/components/block/block.component.yml

$schema: https://git.drupalcode.org/project/drupal/-/raw/HEAD/core/assets/schemas/v1/metadata.schema.json
name: Block
slots:
  label:
    title: Label
    examples:
      - <h2>Example Block Label</h2>
  content:
    title: Content
    examples:
      - Example Block Content
props:
  type: object
  properties:
    attributes:
      type: Drupal\Core\Template\Attribute
      name: Attributes
      title: Attributes
      examples:
        - class: [ 'example-class-attribute' ]
    label_attributes:
      type: Drupal\Core\Template\Attribute
      name: Attributes
      title: Attributes
      examples:
        - class: [ 'example-label-class-attribute' ]