I need to make my mind clear about HTML doctypes. in this page: http://kovo.intl.uk.to I add breadcrumbs navigation using RDFa. but then page was no more valid. I googled and I found out to change doctype to:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN" "http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd">
Now the page is 100% valid, but what means XHTML and such LOW number? At my webpages I am using HTML 4.01 strict due I write pages mostly in Slovak for Slovak people and what I see on some computers and how they are used is "stone age" (Windows XP + ie8 in better case :D).
Is this correct solution and what affects have doctypes to users or search engines ?
Try to use this
<!DOCTYPE html>
<html vocab="http://www.w3.org/2011/rdfa-context/rdfa-1.1">
<head> <title>Kovove webstránky</title>
<!-- Just for validation purpose the if clause -->
<!--[if IE]><meta http-equiv="X-UA-Compatible" content="IE=edge" /><![endif]-->
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<link rel="stylesheet" href="../css/main.css" />
<script type="text/javascript" src="../js/jquery-1.8.3.min.js"></script>
<script type="text/javascript" src="../js/anim.js"></script>
</head>
<body>
<div class="pagewrap">
<div class="menu vrch">
<div class="aktivna">
<a class="pol" href="http://kovo.intl.uk.to/index.php"><span>Domov</span></a>
<a class="arrowh" href="http://kovo.intl.uk.to/index.php">
<span></span>
<span></span>
</a>
</div>
<div class="">
<a class="pol" href="http://kovo.intl.uk.to/tvorba"><span>Tvorba</span></a>
<a class="arrowh" href="http://kovo.intl.uk.to/tvorba">
<span></span>
<span></span>
</a>
</div>
<div class="">
<a class="pol" href="http://kovo.intl.uk.to/blog"><span>Blog</span></a>
<a class="arrowh" href="http://kovo.intl.uk.to/blog">
<span></span>
<span></span>
</a>
</div>
<div class="">
<a class="pol" href="http://kovo.intl.uk.to/ine"><span>Daco iné</span></a>
<a class="arrowh" href="http://kovo.intl.uk.to/ine">
<span></span>
<span></span>
</a>
</div>
</div>
<div class="menu nalavo">
<div class="aktivna">
<a class="ico" rel="nofollow" href="">
</a>
<a class="arrow" rel="nofollow" href="">
<span></span>
<span></span>
</a>
</div>
</div>
<div class="stred">
<div class="telo">
<div class="bread">
<div>
<span typeof="v:Breadcrumb">
<a href="http://kovo.intl.uk.to" rel="v:url" property="v:title">kovo.intl.uk.to</a> >
</span>
</div>
<div>
<span typeof="v:Breadcrumb">
Domovská stránka </span>
</div>
</div>
<h1>Nadpis 1 </h1>
blablablabla
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blablablabla
blablablabla
blablablablablablablablablablablablablablablablablablablablablablablablablablab
lablablablablablablablablsdasdasdasdasdasdasdsdfsdgdfgdfgdfgdfgdfgdfgdfgdfgdfgdfgdfgfdg
ablablablablablablablablablablablablablablablablablablablablablablablablablabl
ablablablablablablablablablablablablablablablablablablabla
</div>
</div>
<div class="peta">
<span class="left">© 2014 Matej Kovác</span>
<span class="right"><a href="http://validator.w3.org/check?uri=referer">(X)HTML valid</a></span>
</div>
</div>
</body>
</html>
On the other hand you should read more about the semantic web.
This validates ok!
RDFa 1.0 can be used in XHTML 1.0 (using the DOCTYPE included in your question).
RDFa 1.1 can be used in probably any (X)HTML version (all interpreted through the HTML5 parsing rules), i.e.: HTML5, XHTML5, HTML 4.01, XHTML 1.0, XHTML 1.1, …:
HTML+RDFa 1.1 (W3C Recommendation 22 August 2013)
Support for RDFa in HTML4 and HTML5
XHTML+RDFa 1.1 - Second Edition (W3C Recommendation 22 August 2013)
Support for RDFa via XHTML Modularization
XHTML 1.0 is "a reformulation of the three HTML 4 document types as applications of XML 1.0"
So you are fine, it's still an equivalent of HTML 4:
There are three formal DTDs for XHTML 1.0, corresponding to the three different versions of HTML 4.01:
- XHTML 1.0 Strict is the XML equivalent to strict HTML 4.01, and includes elements and attributes that have not been marked deprecated in the HTML 4.01 specification. As of May 25, 2011, XHTML 1.0 Strict is the document type used for the homepage of the website of the World Wide Web Consortium.
- XHTML 1.0 Transitional is the XML equivalent of HTML 4.01 Transitional, and includes the presentational elements (such as center, font and strike) excluded from the strict version.
- XHTML 1.0 Frameset is the XML equivalent of HTML 4.01 Frameset, and allows for the definition of frameset documents—a common Web feature in the late 1990s.
XHTML+RDFa is one of the techniques used to develop Semantic Web content by embedding rich semantic markup. Version 1.1 of the language is a superset of XHTML 1.1
来源：https://stackoverflow.com/questions/21557030/right-doctype-for-rdfa-breadcrumbs-navigation-and-validator