HTML5的结构和语义——语义性的块级元素（三）
HTML 5 还增加了一些纯语义性的块级元素：
aside figure dialog
我在文章和书中一直使用前两个元素。第三个元素我不经常用，它主要用于书面文本。
aside
aside 元素代表说明、提示、边栏、引用、附加注释等，也就是叙述主线之外的内容。例如，在 developerWorks 文章中，常常会看到用表格形式编写的边栏，见代码3 用 HTML 4 编写的 developerWorks 边栏。
1: <table align="right" border="0" cellpadding="0" cellspacing="0" width="40%">
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 2:</span> <span style="color: #0000ff"><</span><span style="color: #800000">tbody</span><span style="color: #0000ff">><</span><span style="color: #800000">tr</span><span style="color: #0000ff">><</span><span style="color: #800000">td</span> <span style="color: #ff0000">width</span><span style="color: #0000ff">="10"</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 3:</span> <span style="color: #0000ff"><</span><span style="color: #800000">img</span> <span style="color: #ff0000">alt</span><span style="color: #0000ff">=""</span> <span style="color: #ff0000">src</span><span style="color: #0000ff">="//www.ibm.com/i/c.gif"</span> <span style="color: #ff0000">height</span><span style="color: #0000ff">="1"</span> <span style="color: #ff0000">width</span><span style="color: #0000ff">="10"</span><span style="color: #0000ff">></</span><span style="color: #800000">td</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 4:</span> <span style="color: #0000ff"><</span><span style="color: #800000">td</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 5:</span> <span style="color: #0000ff"><</span><span style="color: #800000">table</span> <span style="color: #ff0000">border</span><span style="color: #0000ff">="1"</span> <span style="color: #ff0000">cellpadding</span><span style="color: #0000ff">="5"</span> <span style="color: #ff0000">cellspacing</span><span style="color: #0000ff">="0"</span> <span style="color: #ff0000">width</span><span style="color: #0000ff">="100%"</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 6:</span> <span style="color: #0000ff"><</span><span style="color: #800000">tbody</span><span style="color: #0000ff">><</span><span style="color: #800000">tr</span><span style="color: #0000ff">><</span><span style="color: #800000">td</span> <span style="color: #ff0000">bgcolor</span><span style="color: #0000ff">="#eeeeee"</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 7:</span> <span style="color: #0000ff"><</span><span style="color: #800000">p</span><span style="color: #0000ff">><</span><span style="color: #800000">a</span> <span style="color: #ff0000">name</span><span style="color: #0000ff">="xf-value"</span><span style="color: #0000ff">><</span><span style="color: #800000">span</span> <span style="color: #ff0000">class</span><span style="color: #0000ff">="smalltitle"</span><span style="color: #0000ff">></span>.xf-value<span style="color: #0000ff"></</span><span style="color: #800000">span</span><span style="color: #0000ff">></</span><span style="color: #800000">a</span><span style="color: #0000ff">></</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 8:</span> <span style="color: #0000ff"><</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 9:</span> The <span style="color: #0000ff"><</span><span style="color: #800000">code</span> <span style="color: #ff0000">type</span><span style="color: #0000ff">="inline"</span><span style="color: #0000ff">></span>.xf-value<span style="color: #0000ff"></</span><span style="color: #800000">code</span><span style="color: #0000ff">></span> selector used here styles the input</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 10:</span> field value but not its label. This is actually inconsistent</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 11:</span> with the current CSS3 draft. The example really should use the</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 12:</span> <span style="color: #0000ff"><</span><span style="color: #800000">code</span> <span style="color: #ff0000">type</span><span style="color: #0000ff">="inline"</span><span style="color: #0000ff">></span>::value<span style="color: #0000ff"></</span><span style="color: #800000">code</span><span style="color: #0000ff">></span> pseudo-class instead like so:</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 13:</span> <span style="color: #0000ff"></</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 14:</span> <span style="color: #0000ff"><</span><span style="color: #800000">table</span> <span style="color: #ff0000">border</span><span style="color: #0000ff">="0"</span> <span style="color: #ff0000">cellpadding</span><span style="color: #0000ff">="0"</span> <span style="color: #ff0000">cellspacing</span><span style="color: #0000ff">="0"</span> <span style="color: #ff0000">width</span><span style="color: #0000ff">="100%"</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 15:</span> <span style="color: #0000ff"><</span><span style="color: #800000">tbody</span><span style="color: #0000ff">><</span><span style="color: #800000">tr</span><span style="color: #0000ff">><</span><span style="color: #800000">td</span> <span style="color: #ff0000">class</span><span style="color: #0000ff">="code-outline"</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 16:</span> <span style="color: #0000ff"><</span><span style="color: #800000">pre</span> <span style="color: #ff0000">class</span><span style="color: #0000ff">="displaycode"</span><span style="color: #0000ff">></span>input::value { width: 20em; }</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 17:</span> #ccnumber::value { width: 18em }</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 18:</span> #zip::value { width: 12em }</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 19:</span> #state::value { width: 3em }<span style="color: #0000ff"></</span><span style="color: #800000">pre</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 20:</span> <span style="color: #0000ff"></</span><span style="color: #800000">td</span><span style="color: #0000ff">></</span><span style="color: #800000">tr</span><span style="color: #0000ff">></</span><span style="color: #800000">tbody</span><span style="color: #0000ff">></</span><span style="color: #800000">table</span><span style="color: #0000ff">><</span><span style="color: #800000">br</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 21:</span>  </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 22:</span> <span style="color: #0000ff"><</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 23:</span> However, Firefox doesn't yet support this syntax. </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 24:</span> <span style="color: #0000ff"></</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 25:</span> <span style="color: #0000ff"></</span><span style="color: #800000">td</span><span style="color: #0000ff">></</span><span style="color: #800000">tr</span><span style="color: #0000ff">></</span><span style="color: #800000">table</span><span style="color: #0000ff">></span></pre></p>
在 HTML 5 中，可以按照更有意义的方式编写这个边栏，见代码4 用 HTML 5 编写的 developerWorks 边栏。
1: <aside>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 2:</span> <span style="color: #0000ff"><</span><span style="color: #800000">h3</span><span style="color: #0000ff">></span>.xf-value<span style="color: #0000ff"></</span><span style="color: #800000">h3</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 3:</span> <span style="color: #0000ff"><</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 4:</span> The <span style="color: #0000ff"><</span><span style="color: #800000">code</span> <span style="color: #ff0000">type</span><span style="color: #0000ff">="inline"</span><span style="color: #0000ff">></span>.xf-value<span style="color: #0000ff"></</span><span style="color: #800000">code</span><span style="color: #0000ff">></span> selector used here styles the input</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 5:</span> field value but not its label. This is actually inconsistent</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 6:</span> with the current CSS3 draft. The example really should use the</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 7:</span> <span style="color: #0000ff"><</span><span style="color: #800000">code</span> <span style="color: #ff0000">type</span><span style="color: #0000ff">="inline"</span><span style="color: #0000ff">></span>::value<span style="color: #0000ff"></</span><span style="color: #800000">code</span><span style="color: #0000ff">></span> pseudo-class instead like so:</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 8:</span> <span style="color: #0000ff"></</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 9:</span> </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 10:</span> <span style="color: #0000ff"><</span><span style="color: #800000">pre</span> <span style="color: #ff0000">class</span><span style="color: #0000ff">="displaycode"</span><span style="color: #0000ff">></span>input::value { width: 20em; }</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 11:</span> #ccnumber::value { width: 18em }</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 12:</span> #zip::value { width: 12em }</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 13:</span> #state::value { width: 3em }<span style="color: #0000ff"></</span><span style="color: #800000">pre</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 14:</span>  </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 15:</span> <span style="color: #0000ff"><</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 16:</span> However, Firefox doesn't yet support this syntax. </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 17:</span> <span style="color: #0000ff"></</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 18:</span> <span style="color: #0000ff"></</span><span style="color: #800000">aside</span><span style="color: #0000ff">></span></pre></p>
浏览器可以决定把这个边栏放在哪里（可能需要用一点儿 CSS 代码）。
figure
figure 元素代表一个块级图像，还可以包含说明。例如，在许多 developerWorks 文章中，可以看到代码5 用 HTML 4 编写的 developerWorks 图 这样的标记其结果见图1。
1: <a name="fig2"><b>Figure 2. Install Mozilla XForms dialog</b></a><br />
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 2:</span> <span style="color: #0000ff"><</span><span style="color: #800000">img</span> <span style="color: #ff0000">alt</span><span style="color: #0000ff">="A Web site is requesting permission to install the following item: </pre>
3: Mozilla XForms 0.7 Unsigned"</span>
4: src="installdialog.jpg" border="0" height="317" hspace="5" vspace="5" width="331" />
5: <br />
图 1. Install Mozilla XForms dialog 
在 HTML 5 中，可以按照更有语义性的方式编写这个图，见代码6 用 HTML 5 编写的 developerWorks 图。
1: <figure id="fig2">
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 2:</span> <span style="color: #0000ff"><</span><span style="color: #800000">legend</span><span style="color: #0000ff">></span>Figure 2. Install Mozilla XForms dialog<span style="color: #0000ff"></</span><span style="color: #800000">legend</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 3:</span> <span style="color: #0000ff"><</span><span style="color: #800000">img</span> <span style="color: #ff0000">alt</span><span style="color: #0000ff">="A Web site is requesting permission to install the following item: </pre>
4: Mozilla XForms 0.7 Unsigned"</span>
5: src="installdialog.jpg" border="0" height="317" hspace="5" vspace="5" width="331" />
6: </figure>
最重要的是，浏览器（尤其是屏幕阅读器）可以明确地将图和说明联系在一起。
figure 元素不只可以显示图片。还可以使用它给 audio、video、iframe、object 和 embed 元素加说明。
dialog
dialog 元素表示几个人之间的对话。HTML 5 dt 元素可以表示讲话者，HTML 5 dd 元素可以表示讲话内容。所以，在老式浏览器中也可以以合理的方式显示对话。代码7 显示在 Galileo 的 “Dialogue Concerning the Two Chief World Systems” 上的一段著名对话。
代码7. 用 HTML 5 编写的 Galilean 对话
1: <dialog>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 2:</span> <span style="color: #0000ff"><</span><span style="color: #800000">dt</span><span style="color: #0000ff">></span>Simplicius <span style="color: #0000ff"></</span><span style="color: #800000">dt</span><span style="color: #0000ff">></span> </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 3:</span> <span style="color: #0000ff"><</span><span style="color: #800000">dd</span><span style="color: #0000ff">></span>According to the straight line AF,</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 4:</span> and not according to the curve, such being already excluded</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 5:</span> for such a use.<span style="color: #0000ff"></</span><span style="color: #800000">dd</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 6:</span>  </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 7:</span> <span style="color: #0000ff"><</span><span style="color: #800000">dt</span><span style="color: #0000ff">></span>Sagredo <span style="color: #0000ff"></</span><span style="color: #800000">dt</span><span style="color: #0000ff">></span> </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 8:</span> <span style="color: #0000ff"><</span><span style="color: #800000">dd</span><span style="color: #0000ff">></span>But I should take neither of them,</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 9:</span> seeing that the straight line AF runs obliquely. I should</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 10:</span> draw a line perpendicular to CD, for this would seem to me</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 11:</span> to be the shortest, as well as being unique among the</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 12:</span> infinite number of longer and unequal ones which may be</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 13:</span> drawn from the point A to every other point of the opposite</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 14:</span> line CD. <span style="color: #0000ff"></</span><span style="color: #800000">dd</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 15:</span>  </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 16:</span> <span style="color: #0000ff"><</span><span style="color: #800000">dt</span><span style="color: #0000ff">></span>Salviati <span style="color: #0000ff"></</span><span style="color: #800000">dt</span><span style="color: #0000ff">></span> </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 17:</span> <span style="color: #0000ff"><</span><span style="color: #800000">dd</span><span style="color: #0000ff">><</span><span style="color: #800000">p</span><span style="color: #0000ff">></span> Your choice and the reason you</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 18:</span> adduce for it seem to me most excellent. So now we have it</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 19:</span> that the first dimension is determined by a straight line;</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 20:</span> the second (namely, breadth) by another straight line, and</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 21:</span> not only straight, but at right angles to that which</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 22:</span> determines the length. Thus we have defined the two</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 23:</span> dimensions of a surface; that is, length and breadth. <span style="color: #0000ff"></</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 24:</span>  </pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 25:</span> <span style="color: #0000ff"><</span><span style="color: #800000">p</span><span style="color: #0000ff">></span> But suppose you had to determine a height—for</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 26:</span> example, how high this platform is from the pavement down</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 27:</span> below there. Seeing that from any point in the platform we</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 28:</span> may draw infinite lines, curved or straight, and all of</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 29:</span> different lengths, to the infinite points of the pavement</pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 30:</span> below, which of all these lines would you make use of? <span style="color: #0000ff"></</span><span style="color: #800000">p</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: white; border-bottom-style: none"><span style="color: #606060"> 31:</span> <span style="color: #0000ff"></</span><span style="color: #800000">dd</span><span style="color: #0000ff">></span></pre>
<pre style="padding-right: 0px; padding-left: 0px; font-size: 8pt; padding-bottom: 0px; margin: 0em; overflow: visible; width: 100%; color: black; border-top-style: none; line-height: 12pt; padding-top: 0px; font-family: consolas, 'Courier New', courier, monospace; border-right-style: none; border-left-style: none; background-color: #f4f4f4; border-bottom-style: none"><span style="color: #606060"> 32:</span> <span style="color: #0000ff"></</span><span style="color: #800000">dialog</span><span style="color: #0000ff">></span></pre>
</p>
对于这个元素的准确语法还有争议。一些人希望在 dialog 元素中嵌入非对话文本（比如剧本中的舞台说明），还有人不喜欢扩展 dt 和 dd 元素的作用。尽管在具体语法方面有争议，但是大多数人都认为以这样的语义性方式表达对话是好事情。
最后修改于 2008-03-09