HTML and CSS Reference
specified, and must not be specified on elements with an item-
scope attribute whose itemtype attribute specifies a vocabulary
that does not support global identifiers for items, as defined by
that vocabulary's specification.”
For more information about Microdata, we recommend
“Extending HTML5—Microdata” by Oli Studholme
“Microdata Tutorial” by Tab Atkins, Jr.
“Using Multiple Vocabularies in Microdata” by Jeni Tennison
The Microdata DOM API
Microdata also has an associated DOM API to manipulate items
and properties which gives the document.getItems() method to
grab a nodelist containing Microdata items on a page. Without
an argument, the method gets all the items on a page, or pass-
ing an itemtype URL returns only items with that itemtype.
At time of writing, only pre-release versions of Opera 12 support
the DOM API.
In Chapter 1 you saw <aside> used to mark up sidebars. It rep-
resents “a section of a page that consists of content that is tan-
gentially related to the content around the aside element, and
which could be considered separate from that content. Such
sections are often represented as sidebars in printed typogra-
phy. The element can be used for typographical effects like pull
quotes or sidebars, for advertising, for groups of nav elements,
and for other content that is considered separate from the main
content of the page.”
Using an <aside> inside an <article> , for example, is the right
place for tangentially related information or pull quotes about
that article, but not, we hasten to add, page-wide navigation.
<aside> has an implied ARIA role of note , but can be given
role=”complementary” or (if it surrounds a search form)