问题
Is it obligatory to write Product node (parent) before Offer node (child) in DOM schema of schema.org or I can define Offer node without its parent node?
回答1:
Schema.org never requires the existence of "parent" items (unless you use itemprop on an element with itemscope).
So this is totally fine:
<html itemscope itemtype="http://schema.org/Offer">
</html>
But even if you would want to add a Product, it doesn’t have to be a parent for Offer.
You can nest the Product under Offer:
<div itemscope itemtype="http://schema.org/Offer">
<div itemprop="itemOffered" itemscope itemtype="http://schema.org/Product"></div>
</div>
Or you can have both on the same level and use itemref:
<div itemscope itemtype="http://schema.org/Offer" itemref="foo">
</div>
<div itemprop="itemOffered" itemscope itemtype="http://schema.org/Product" id="foo">
</div>
来源：https://stackoverflow.com/questions/22994941/define-parent-node-before-child-in-schema-org