HTML and CSS Reference
In-Depth Information
<div itemscope itemtype=”http://schema.org/Book”>
I love that <span itemprop=”name”>Introducing HTML5</span>
By
<span itemprop=”author” itemscope itemtype=
¬ ”http://microformats.org/profile/hcard”>
<span itemprop=”fn”>Bruce Lawson</span>
</span>
and
<span itemprop=”author” itemscope itemtype=
¬ ”http://microformats.org/profile/hcard”>
<span itemprop=”fn”>Remy Sharp</span>
</span>
(ISBN <span itemprop=”isbn”>0321784421</span>)
</div>
Microdata is as simple as that for the majority of use-cases.
There are, however, two more attributes that we'll mention for
completeness.
NoTE
This is a silly micro-
data example as it gives
no further information about our
authors than their names; the
purpose is to demonstrate the
nesting. Much fuller examples
can be found in the spec at
itemref
Sometimes, you might want to list additional elements for a user
agent to crawl in order to find the name-value pairs of the item,
because those elements aren't descendents of the element with
the
itemscope
attribute. On the element with itemscope, you can
list unique, space-separated tokens that are case-sensitive and
correspond to IDs of elements in the same page.
itemid
If you want to, you can use an
itemid
attribute. This is a globally
unique identifier—not just on your website, but on the whole
Web. It could, for example, be an ISBN or a URL or anything
that you can guarantee to be unique, really. Doing this sprinkles
magical Semantic Web pixie dust all over your website, and
crawlers and content aggregators will “know” that your content
is talking about the same things as my content because they
share the same itemid. (At time of writing, though, the Microdata
vocabularies published by Bing, Google, and Yahoo! on schema.
org don't use itemid at all.)
If you want to use itemid, you must use a vocabulary that sup-
ports global identifiers:
“The itemid attribute must not be specified on elements that do
not have both an itemscope attribute and an itemtype attribute
