I've been doing some searching around and couldn't find this topic anywhere. My company wants to use an HTML doctype but wordpress outputs XHTML by default. I've seen plugins and I would use these but this site will probably outlive the development of said plugins. Plus it's something else to account for when updating or building new sites.
If I use an XHTML doctype how will HTML5 browsers render it? Will they be backwards-compatible with old doctypes?
Edit 1: It is actually recomended that in order to make the transition to HTML5 easier that you try to follow the XHTML structure when writing any HTML.
There will be additional options and types with XHTML in HTML5 but a lot of it is based on the structure in which you are writing your HTML. The X simply means that it is moving to more of an XML base.
To go along with Kayla's input, you will want to make sure that all tags are being closed:
<br/> Instead of: <br>
You will also want to make sure to put quotations around any parameters:
<a href="value"></a> Instead of: <a href=value></a>
Browsers have been slowly adopting the XHTML structure. This might mean that HTML that is formatted without end tags/etc might look a little different in IE 6 than in newer brower versions. Hope that helps!
It is not recommended to use the XHTML 1.0 or 1.1 doctypes for your HTML5 pages, one because its unnecessary and two your markup won't validate when you use the newer tags. Here is a quick guide on using XML syntax in HTML5 a.k.a. XHTML5.
Update: As noted bellow checkout the W3C Specification.
I am not sure what you are asking. What do plugins have to do with DTD?
Yes, any browsers that supports HTML5 is backwards compatible with (X)HTML, you can mix and match all you want. And basically as long as you are writing tags like:
<div>Hi</div> or <p>There</p>
instead of
<DIV>Hi</DIV> or <P>There</P>
the rest is just semantics.
HTML5 began life specifically because browsers manufacturers wanted to make sure that changes they introduced were backward compatible with existing web pages, in contrast to the now defunct XHTML 2, which was shaping up to be non-backward compatible.
So yes, your XHTML doctype will work just fine in HTML5 browsers.
As far as I know all modern browsers that are adding HTML 5 support will continue to support HTML 4 and XHTML for the foreseeable future so you should be fine.
If you're using Wordpress though stick with XHTML. It'll be supported for a long time to come in all browsers and most Wordpress plugins are designed to output XHTML.
