When doing a html5 validation test i am getting almost no errors. :-) Except

Error: Bad value category tag for attribute rel on element a: The string category is not a registered keyword or absolute URL.
From line 230, column 30; to line 230, column 142
tegories"><a href="http://decomputer.be/category/software/" title="Alle berichten bekijken in Software" rel="category tag">Softwa
Syntax of link type valid for <a> and <area>:
A whitespace-separated list of link types, with no duplicate keywords in the list. Each link type must be listed as allowed on <a> and <area> in the HTML specification, or must be listed as allowed on <a> and <area> on the Microformats wiki, or must be an absolute URL. You can register link types on the Microformats wiki yourself.

Is this something that i can easely correct?

What validation are you using

http://validator.w3.org/check?uri=de...Inline&group=0

Of course i can remove the tags and the part that doesn't validate. But i want to hear your opinion first.

I don't worry avbout validation. If you note it is an expiremental validator.

Try this, swap to twenty-twelve and validate the site again and see what you come up with.