HTML tags: optgroup, sub, sup and bdo

Author：Eve Cole Update Time：2025-05-15 18:00:04

Optgroup is used in select tags to make the drop-down list content more organized

sub superscript

sup subscript can be used with for comment

Use dbo dir marks together to change the output direction of text, right->left

eg:

Demo code:

<!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>4 uncommon html tags optgroup, sub, sup and bdo. - www.VeVb.com</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></head><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=aspBuilt-in objects><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 Superscript x2 x2 Subscript x2 Combined with tags, it can be used for comments, example: flyingNote: html xhtml web encoding moderator</fieldset><fieldset><legend>bdo tag</legend><bdo dir=ltr>I love you very much</bdo> <bdo dir=rtl>You love you very much</bdo> The output result is <bdo dir=ltr>I love you very much</bdo> />Note: When using the bod tag, you must use the dir tag attribute in succession. ltr refers to the orchestration order from left to right, and rtl refers to the orchestration order from right to left. </fieldset></body></html>

[ctrl+a All selection tips: You can modify some code first, and then press Run]