Why <? Xml version = "1.0" encoding = "UTF-8"?> Should not be placed at the very top?

Question

Please explain to me what problems (if any) by placing the following ad at the very top of the HTML page

<?xml version="1.0" encoding="UTF-8"?>

Answer 1

This is not very good, because it will cause IE6 to go into quirky mode.

http://www.456bereastreet.com/archive/200904/using_an_xml_declaration_triggers_quirks_mode_in_ie_6/

And if you've ever worked with IE6 in quirks mode, you would know what a painful experience.

Answer 2

, . , , , .

, UTF-8 UTF-16. . , .

IE6, IE6 "quirks", .

... IE6 - .

.

Answer 3

, .

• ( ) ,
• , XHTML , " ", HTML. XML.

Also, if you use XML / XHTML, make sure that you also send the correct content type header (for example, application / xml instead of text / html).