Do I need to declare XML on a page using the XHTML doctype?
doctype, html, xhtml, xml
Solution
<?xml version="1.0" encoding="utf-8"?>
...is the default version and encoding for XML, so you don't need it at all. If you are serving XHTML as text/html, it probably shouldn't be there at all.
However, in other places I'm seeing (including w3.org) that the DOCTYPE must be the first tag.
Sounds like some confusion... DOCTYPE isn't a tag and neither is <?xml?> (which is called the XML declaration, and looks like a Processing Instruction, but it isn't one of those, either).
If you are including both, the XML declaration must come first. The trick is that IE6's DOCTYPE sniffer only detects Standards Mode DOCTYPEs if they're the first thing on the page, which means you can't use an XML declaration and you must stick with XML 1.0 and UTF-8 encoding (which is no great loss).
Problem
I've been seeing some conflicting information that an XHTML document must also declare itself as XML. ``` <?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"> ``` However, in other places I'm seeing (including w3.org) that the DOCTYPE must be the first tag declaration. Since W3 says it, it must be true. However, I probably have some pages/apps lying about that are following the first method. What are my risks? Edit: I just ran a page through the W3 Validator with and without the XML declaration and it passed both ways. At this point, then, I'm guessing it's just a "style" thing.