The usage and sample code of the optgroup, sub, sup, and bdo of HTML tags. For more information, see. Optgroup can be used in the select tag to make the drop-down list more organized.
The Code is as follows:
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Sub tagging
Sup subscript can be used
For comments together
The dbo dir mark can be used together to change the output direction of the text, right-> left
<! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Transitional // EN "" http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd "> <Html xmlns =" http://www.w3.org/1999/xhtml "> <Head> <meta http-equiv =" Content-Type "content =" text/html; charset = gb2312 "/> <title> four uncommon HTML tags optgroup, sub, sup, and bdo. </Title> <style type = "text/css"> fieldset {width: 300px; padding: 5px 5px; margin: 30px auto; display: block; line-height: 125%; font-size: 15px;} legend {margin-left: 15px; font-size: 18px; color: red;} bdo {color: red ;} </style> </pead> <body> <fieldset> <legend> optgroup </legend> <select> <optgroup label = "HTML Tag"> <option> table </ option> <option> tr </option> <option> td </option> <option> th </option> </optgroup> <optgroup label =" SP built-in object "> <option> cookies </option> <option> session </option> <option> application </option> <option> redirect </option> </optgroup> </select> <optgroup label = ""> <option> .... </option> </optgroup> </select> </fieldset> <fieldset class = "sub"> <legend> sub tag </legend> X2 supermark X2X2 subscript X2 <pr /> combined with <em> labels can be used for annotation, example: flying <em> note: html xhtml webpage code moderator </em> </fieldset> <legend> bdo tag </legend> <bdo dir = "ltr"> I love you very much </bdo> <bdo Dir = "rtl"> You Love Me often </bdo> the output result is <bdo dir = "ltr"> I love you very much </bdo> <bdo dir = "rtl"> you love me often. </bdo> note: you must use the dir label attribute when using the bod label. ltr refers to the orchestration sequence from left to right and rtl refers to the orchestration sequence from right to left. </P> </fieldset> </body> </ptml>