The itemid
global attribute provides microdata in the form of a unique, global identifier of an item.
An itemid
attribute can only be specified for an element that has both itemscope
and itemtype
attributes. Also, itemid
can only be specified on elements that possess an itemscope
attribute whose corresponding itemtype
refers to or defines a vocabulary that supports global identifiers.
The exact meaning of an itemtype
's global identifier is provided by the definition of that identifier within the specified vocabulary. The vocabulary defines whether several items with the same global identifier can coexist and, if so, how items with the same identifier are handled.
Note: The WHATWG definition specifies that an itemid
must be a URL. However, the following example correctly illustrates that a URN may also be used. This inconsistency may reflect the incomplete nature of the Microdata specification.
This example uses microdata attributes to represent the following structured data:
itemscope itemtype: itemid https://schema.org/Book: urn:isbn:0-374-22848-5 itemprop title Owls of the Eastern Ice itemprop author Jonathan C Slaght itemprop datePublished 2020-08-04 HTML<dl
itemscope
itemtype="https://schema.org/Book"
itemid="urn:isbn:0-374-22848-5<">
<dt>Title</dt>
<dd itemprop="title">Owls of the Eastern Ice</dd>
<dt>Author</dt>
<dd itemprop="author">Jonathan C Slaght</dd>
<dt>Publication date</dt>
<dd>
<time itemprop="datePublished" datetime="2020-08-04">August 4 2020</time>
</dd>
</dl>
Result Specifications See also
All global attributes.
Other microdata related global attributes:
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