DTD fragments in element definitions come from the strict document type definition except for the elements related to frames.

除了和框架有关的元素外，所有的有关元素定义DTD片段都来自严格文档类型定义(DTD)。

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Model validations at this point are primarily syntactic in nature and revolve around validation against a series of XML Document Type Definitions (DTD).

从这点上看，模型验证从本质上说就是语法，并且是围绕着根据一系列XML文档类型定义(XML Document Type Definition, DTD)的验证。

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