Returns the type of item, as a schema component, if any. If the item has no type, the empty sequence is returned. The context item is used if no argument is given.

• If the item is a document node, the result is the type of its root element.
• If the item is an element node, the result is the type of its element declaration.
• If the item is an attribute node, the result is the type of its attribute declaration.
• If the item is a schema component, the result is the associated type schema component.
• If the item is an atomic value, the result is the type of that atomic value.
• In other cases, the result is the empty sequence.