HTML Checking for Large Sites
Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.
HTML issues tagged as itemscope.
An itemprop attribute has been found in the document, but it cannot be associated to any item. Most probable cause is the lack of an itemscope attribute defining an item.
Microdata allows nested groups of properties, which must be scoped to the item they belong to, as in this example:
<div itemscope>
<p>My name is <span itemprop="name">Liza</span> and I'm <span itemprop="age">48</span> years old.</p>
</div>
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