Microdata has strict requirements about where to place the microdata attributes in the HTML, so each field type in Drupal needs to define where to place the attribute within its formatters.
对于在 HTML 中放置微数据属性的位置，微数据有严格的要求，因此 Drupal 中的每种字段类型都需要定义在其格式器中放置属性的位置。
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Schema.org relies on the Microdata format, a W3C HTML markup specification.