This has many examples in the wild, such as HTML DOCTYPE, some USES of XMLNS, a version identifier inside your PDF document.

这样的例子有很多，如HTML DOCTYPE, XMLNS的某些使用或PD F文档中的某个版本标识。

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First, the only trigger for a browser to parse in standards mode is a DOCTYPE as the first line of an HTML or XHTML document, as Listing 1 shows.

首先，让浏览器用标准模式解析的惟一条件是HTML或XHTML文档的第一行包含DOCTYPE，如清单1所示。

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While the DOCTYPE declaration informs a browser to use standards mode, it will still parse the HTML according to the rules in that DTD — in this case, HTML 4.0.

虽然DOCTYPE声明告诉浏览器使用标准模式，但是它仍然会根据那个DTD——即HTML 4.0的规则去解析html。

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