I am trying to get my pages validated using Markup Validation Service on W3C validator.
We are getting validation against the XHTML 1.0 Strict doctype comes back with the following error:
... there is no attribute "data-gid"
Because of the following code:
<a href="#" class="addToCartLink" data-gid="202">Add to Inquiry List</a>
From the follwing page: http://dev.contractorshire.co.uk/catalog/plant/mini-digger/.
We have been advised that we need to use the Html5 doctype. We have changed to the above doctype on this page now however the point of this excercise was to make sure the site is clean to help with SEO.
I would like to use the html5 doctype with html5 markup.
Here is the questoin: Is there any difference, from SEO perspective, between valid HTML5 or XHTML 1.0 Strict? Should I try to stay on (valid) XHTML 1.0 Strict doctype/markup or is it OK to move to vallid HTML5 doctype/markup?