Don’t worry too much about validation errors, there is nothing wrong and it’s perfectly normal. Check this:
———————-
The rel=”category tag” is part of the rel-category microformat specification:
http://microformats.org/wiki/rel-category
Note that the W3C validator tools are meant as guides, not to be taken as absolute truths. Their checks may not be up to date with the current standards that are in widespread use.
———————–