Used for advanced searches. Terms should be drawn from the approved list.
"property-name" — adds a property to a microdata item. The name of the property can be a word or URL, and the value is the ‘content’ of the element with this attribute.
Defines a group of name-value pair(s), called an item
defines the item’s type when used on the same element as itemscope. The itemtype value is a URL that acts as an identifying vocabulary name.