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用doctype激活浏览器模式（4）

作者：秦歌　来源：随网之舞　发布时间：2009-06-15 19:02:00　

标签：doctype,内容,浏览器,Firefox,模式

补遗：对XML的实现者和规范作者的恳求

请不要把doctype嗅探带到XML。

doctype嗅探是用签杂烩汤似的方法解决一个标签杂烩汤问题。doctype嗅探是在HTML4和CSS2规范发布后设计的一种试探方法，它从文档中区分出过时文档以符合其作者可能期望的行为。

偶尔有人建议在XML上使用doctype嗅探来调度不同的处理、识别正在使用的词汇表或激活特性。这是个坏主意。调度和词汇表识别应该是基于名字空间的，而特性激活应该是基于明确的处理指令或元素。

良构（well-formedness）的整个思想是介绍允许XML的无DTD解析，且推广无doctype文档。在正式情况下，两个XML文档有相同的规范形式且应用不同地处理它们（且不同之处并非因为没有选择处理外部实体），这个应用或许被破坏了。在实践情况下，如果两个XML文档导致同样的内容被报告（qnames忽略）给SAX2内容处理器且应用不同地处理文档，这个应用或者被破坏了。考虑到作为 Web作者无法相信每个人都会使用解决额外实体的XMLprocessor来解析其页面（即使一些浏览器看起来这样做，因为它们会映射一定公共的标识符到一个有删节的定义实体的DTD），插入doctype到XML中用于Web是毫无意义的且通常会导致货运崇拜（cargo cultish）习惯。(您仍然使用W3C验证器的DTD覆盖功能来对一个DTD进行验证，虽然W3C验证器会说结果仅仅是暂时有效。或更好的是，你可以用放宽NG验证，它不会污染模式引用的文档。)为了嗅探而要求doctype是非常愚蠢的，即使那是在HTML实践中的解决方法。

此外，当低级别的规范定义两个相等的东西时，高级别的规范不应该尝试给它们不同的含义。请考虑<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">。如果删除公共标识符，依旧指定了同样的DTD，因此doctype <!DOCTYPE html SYSTEM "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">表示和前面的doctype一样。应该不同地嗅探它们么？可以进一步理论。假设复制给example.com一个叫foobar.dtd的DTD：<!DOCTYPE html SYSTEM "http://example.com/foobar.dtd">。这该如何嗅探？应该是同一个意思。甚至整个DTD可以贴在文档中。

换句话说，如果有#include “foo.h”，你不应该给名字foo.h绑定任何black magic，因为它应该允许复制foo.h的内容到文档中或复制foo.h到bar.h中且表示#include “bar.h”。

我不担心HTML和SGML构造相同的参数的原因是Web浏览器不会使用真正的SGML解析器去解析HTML，所以我认为伪装成SGML进行处理是没有用的。无论如何，如果你还不相信，请看W. Eliot Kimber关于此事的文章 comp.text.sgml

附录：text/html中一些doctype的处理方式

下表中，怪癖模式、标准模式和几乎标准分别表示为Q、S和A。当浏览器仅有两种模式时，如果表格单元格的行高和Mozilla的标准模式表现一致时，标准模式标记为“S”，如果表格单元格的行高和Mozilla的几乎标准模式表现一致时，则标记为“A”。

请注意使用XML内容模型提供服务的XHTML在XML模式下渲染。

本表的目的并不是说表中所有的doctype都是新建页面的合理选择。本表的目的是为了展示我的推荐是依据什么样的数据。

下列的简写符号是用于列标题：

NS6
Mozilla 0.6…0.9.4 和 Netscape 6.0…6.2.3
Old Moz
Mozilla 0.9.5 到 1.1 alpha 和 Mozilla 1.0
Moz & Safari & Opera 10 & HTML5
Mozilla 1.0.1, Mozilla 1.1 beta和更高版本, Firefox 到 Netscape 7, Safari 0.9 到 Safari 4.0 beta, Opera 10, Chrome, Konqueror 3.5, HTML5指定的行为
Opera 9.0
Opera 9.0…9.20
IE 8 & Opera 9.5
无 X-UA-Compatible和兼容模式覆盖的默认IE8（该情况下“A”意味着IE8几乎标准模式）、 Opera 7.5…8.54 和 9.5…9.6
IE 7 & Opera 7.10
IE7、兼容模式且无X-UA-Compatible覆盖的IE8（这种情况下“A”意味IE7模式）和Opera 7.10…7.23
IE 6 & Opera 7.0
Windows IE 6 和 Opera 7.0…7.03
Mac IE 5
Mac IE 5.0…5.2.3
Konq 3.2
Konqueror 3.2.2…3.3 (也可能包括 3.1…3.2.1; 我尚未确定)

运行代码框
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><HTML> <HEAD> <TITLE> New Document </TITLE> <META NAME="Generator" CONTENT="EditPlus"> <META NAME="Author" CONTENT=""> <META NAME="Keywords" CONTENT=""> <META NAME="Description" CONTENT=""><link rel="stylesheet" href="/wp-content/themes/dancewithnet/style.css" type="text/css" media="all" /> </HEAD> <BODY><table class="small stat"><thead><tr><th>Doctype</th><th>NS6 </th><th>Old Moz </th><th>Moz & Safari & Opera10 & HTML5</th><th>Opera9.0</th><th>IE8 & Opera9.5 </th><th>IE7 & Opera7.10 </th><th>IE6 & Opera7.0 </th><th>Mac IE5 </th><th>Konq3.2 </th></tr></thead><tr><th><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=">None</a> </th><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+3.2+Final％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 3.2 Final//EN”></a></code> </th><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.0％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0//EN”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.01％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01//EN”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td><td class="almost">A</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.0％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fhtml4％2Fstrict.dtd％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0//EN” “http://www.w3.org/TR/html4/strict.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.01％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fhtml4％2Fstrict.dtd％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01//EN” “http://www.w3.org/TR/html4/strict.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.0+Transitional％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”></a></code> </th><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.01+Transitional％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”></a></code> </th><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.01+Transitional％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fhtml4％2Floose.dtd％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN” “http://www.w3.org/TR/html4/loose.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.01+Transitional％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2F1999％2FREC-html401-19991224％2Floose.dtd％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN” “http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd”></a></code> </th><td class="quirks">Q</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+HTML+4.0+Transitional％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fhtml4％2Floose.dtd％22％3E"><!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN” “http://www.w3.org/TR/html4/loose.dtd”></a></code> </th><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+1.1％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fxhtml11％2FDTD％2Fxhtml11.dtd％22％3E"><!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN” “http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+Basic+1.0％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fxhtml-basic％2Fxhtml-basic10.dtd％22％3E"><!DOCTYPE html PUBLIC “-//W3C//DTD XHTML Basic 1.0//EN” “http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+1.0+Strict％2F％2FEN％22+％22http％3A％2F ％2Fwww.w3.org％2FTR％2Fxhtml1％2FDTD％2Fxhtml1-strict.dtd％22％3E"><!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+1.0+Transitional％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fxhtml1％2FDTD％2Fxhtml1-transitional.dtd％22％3E"><!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％3Fxml+version％3D％221.0％22+encoding％3D％22UTF-8％22％3F％3E％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+1.1％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fxhtml11％2FDTD％2Fxhtml11.dtd％22％3E"><?xml version=”1.0″ encoding=”UTF-8″?> <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN” “http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="quirks">Q</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％3Fxml+version％3D％221.0％22+encoding％3D％22UTF-8％22％3F％3E％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+Basic+1.0％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fxhtml-basic％2Fxhtml-basic10.dtd％22％3E"><?xml version=”1.0″ encoding=”UTF-8″?> <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML Basic 1.0//EN” “http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="quirks">Q</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％3Fxml+version％3D％221.0％22+encoding％3D％22UTF-8％22％3F％3E％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+1.0+Strict％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fxhtml1％2FDTD％2Fxhtml1-strict.dtd％22％3E"><?xml version=”1.0″ encoding=”UTF-8″?> <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="quirks">Q</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％3Fxml+version％3D％221.0％22+encoding％3D％22UTF-8％22％3F％3E％3C％21DOCTYPE+html+PUBLIC+％22-％2F％2FW3C％2F％2FDTD+XHTML+1.0+Transitional％2F％2FEN％22+％22http％3A％2F％2Fwww.w3.org％2FTR％2Fxhtml1％2FDTD％2Fxhtml1-transitional.dtd％22％3E"><?xml version=”1.0″ encoding=”UTF-8″?> <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22ISO％2FIEC+15445％3A2000％2F％2FDTD+HTML％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “ISO/IEC 15445:2000//DTD HTML//EN”></a></code> </th><td class="quirks">Q</td><td class="standards">S</td><td class="standards">S</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22ISO％2FIEC+15445％3A2000％2F％2FDTD+HyperText+Markup+Language％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “ISO/IEC 15445:2000//DTD HyperText Markup Language//EN”></a></code> </th><td class="quirks">Q</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22ISO％2FIEC+15445％3A1999％2F％2FDTD+HTML％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “ISO/IEC 15445:1999//DTD HTML//EN”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td><td class="quirks">Q</td></tr><tr><th><code><a href="http://hsivonen.iki.fi/doctype/test-quirks.php?doctype=％3C％21DOCTYPE+HTML+PUBLIC+％22ISO％2FIEC+15445％3A1999％2F％2FDTD+HyperText+Markup+Language％2F％2FEN％22％3E"><!DOCTYPE HTML PUBLIC “ISO/IEC 15445:1999//DTD HyperText Markup Language//EN”></a></code> </th><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td><td class="quirks">Q</td></tr><tr><th><code><a href="test-quirks.php?doctype=％3C％21DOCTYPE+html％3E"><!DOCTYPE html></a></code></th><td class="quirks">Q</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="standards">S</td><td class="almost">A</td><td class="almost">A</td><td class="almost">A</td></tr></table> </BODY></HTML>

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用doctype激活浏览器模式（4）

相关链接

补遗：对XML的实现者和规范作者的恳求

附录：text/html中一些doctype的处理方式

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