I added Microdata to the product pages of my site. That leads to some errors. One of these errors is the following:
there is no attribute "itemprop"
The error is related to this source code line:
<div itemprop="offers" itemscope="" itemtype="http://schema.org/Offer">
My Doctype is as follows:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
How would it be possible to make the page W3C compliant when keeping the same Doctype?
Microdata can only be used in (X)HTML5.
If you want to use the Schema.org vocabulary in XHTML 1.1, you could use RDFa, but this would require changing the DOCTYPE to
(See my answer about differences between Microdata and RDFa.)