"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.

The lang attribute (in no namespace) specifies the primary language for the element's contents and for any of the element's attributes that contain text. Its value must be a valid BCP 47 language tag.