schema.org 中的产品类别?

用作参考:https://support.google.com/webmasters/answer/146750?hl=zh-CN

您会注意到在产品"下有一个类别属性，此外页面下方还有一个示例:

You will notice under 'Product' that there is a category Property, and furthermore there's an example on down the page:

<span itemprop="category" content="Hardware > Tools > Anvils">Anvils</span>

我完全模仿过:

<span itemprop="category" content="kitchen sinks > stainless steel sinks > undermount">undermount</span>

但是，当我使用 Google 的结构化数据工具对其进行测试时，出现错误:

Yet when I test it with Google's structured data tool, I get the error:

错误:页面包含不属于架构的属性类别".

Error: Page contains property "category" which is not part of the schema.

我也在示例中意识到，它使用的是 data-vocabulary.org→Product，其中我使用的是 schema.org→Product.

I realized in the example also, it's using data-vocabulary.org→Product, where I'm using schema.org→Product.

现在在 http://schema.org/Product 上，它没有任何提及的类别.schema.org 不提供类别吗?还是我遗漏了什么?

Now on http://schema.org/Product, it does not have category anywhere mentioned. Does schema.org not offer categories? Or am I missing something?