I have written this page, because a given local or online validator does not support HTML5 fully (for instance, HTML DOCTYPE is not supported, or XHTML5 is not supported which is part of the spec). or have some common issues which need to be addressed.
validator fails miserably with HTML5 documents, which have either
<!DOCTYPE html ""> or
<!DOCTYPE html> or
<!DOCTYPE html SYSTEM "about:legacy-compat">
there are basically 2 DOCTYPEs supported by HTML5 and XHTML5. the last doctype you see is preferable for inclusion of XML. XHTML only differing in the closing / on void elements and in the need to CDATA your script and style elements. to be sure about the need for CDATA, try making an XHTML1.1/XHTML5 document with a script tag that has an //&& in it. if firefox bails, then you need to put in CDATA.
the void/singleton elements are listed here: http://www.whatwg.org/specs/web-apps/current-work/complete/syntax.html#void-elements
the current living standard draft of the HTML5/XHTML5 spec is here: http://www.whatwg.org/specs/web-apps/current-work/multipage/
how to make an XHTML5 document I have listed on my web page. essentially the difference is the HTML tag having an xmlns attribute specifying the standard XHTML namespace address. I also change the DOCTYPE for compatibility with certain legacy browsers.
XHTML2 standard was dropped (short) in favor of XHTML5.
the situation is, I need a validator that works. adobe doesn't supply one with dw anymore, which is a shame.
the one you have is old by a few years seeing it does not do HTML5.
HTML5 includes SVG and MathML specifications, not as XML namespaces, but as standard tags. which is cool!
there is a separate specification for mobile HTML5/XHTML5/css. http://www.w3.org/Mobile/
XHTML5 requires the "html" part pf the doctype to be in lower case - the doctype is case sensitive and so is XHTML/XHTML5! lower case elements and attributes are required with XHTML5.
stopping short at 20-900 errors is unacceptable. do them all and provide a nice scroll bar. that's what I am paying for. if I want a feature like that, make it something I can turn on and off in an option! but don't force it on me. I work on large web documents 14MB or so. I can't have things breaking down"real soon". and I need to process errors in batch.
features I don't want that I can't turn off that multiply results
for a govt. user, aria, WACTG or whatever those things are will come in handy and are needed. even spell checking. anything that is not basic checking I need to disable for MY purposes personally. others need it.
if your validator app has not made these optional, please make them optional. thanks.
using HTML Tidy
HTML Tidy is nice to have, HOWEVER, it is only HTML 4.x compliant. you need to put this in the manual or at least a warning if the user's code is something other than a format than HTML Tidy can generate or support so the user doesn't go "what happened to my code?".
trying to mix HTML5 tags with HTML 4.0 DOCTYPE will surely be a mess - it gets mangled!