The new schema.org by Google, Yahoo and MS recommends usage of the attribute to display the status of products in an online shop:
&
Link is allowed in BODY. I had same problem validating link tag in HTML5 and I solved it with this
Need to have both property and rel tag
property
rel
UPDATE 2016 (thanks to yuyokk below): There was a change to HTML5 spec recently that allows having links in the body