OptionalcontentGets ContentType indetifier
OptionalexternalDefines the url of another site collection if the item comes from another site collection
Item identifier
Distinguishes the type of the referenced item
List identifier
Gets server relative url of item
Gets display name of item. For generic items the Title field is displayed, for files from the document library the FileLeafRef field is displayed.
Web identifier
Defines the basic structure of the reference.