将元素从可选变为必须涉及到旧文档中没有实例化的可选元素的精化。

Changing an element's optionality from optional to required is related to refinement for those optional elements that are not instantiated on the original document.

youdao

将元素从可选变为必须涉及到旧文档中没有实例化的可选元素的精化。

Changing an element's optionality from optional to required is related to refinement for those optional elements that are not instantiated on the original document.

youdao