The XHTML DTDs will let you create HTML that conforms to the XML standard and can be validated with a parser (more on this later), thereby providing more robust and manageable documents.

XHTML DTD 可使您创建符合 XML 标准并且可以用解析器验证（后面有更多关于这方面的描述）的 HTML，从而提供了更健壮和可管理性更好的文档。

youdao

The downside to this is that, for XHTML, there are several DTDs that define the same document type HTML, so you have to pick one.

这样做的缺点是，对于XHTML，会有几个定义同一文档类型html的DTD，因此必须从中选取一个。

youdao

It was really just an XML variation on HTML 4.01, which has three separate DTDs: strict, transitional, and frameset.

它实际上仅仅是HTML 4.01上的一个XML变体，有三种不同的DTD：严格、过渡和框架集。

youdao