LINK_PARENT

The relation type URI of the of the location of the parent resource in a hierarchy of entries.

This is an undocumented GData-specific addition to the Atom specification, and is not included in the GData documentation except in examples and in the <ulink type="http" url="https://developers.google.com/google-apps/documents-list/v2/schema/document_list_atom.rnc" > RelaxNG schema</ulink>.