http://www.vizrt.com/types/relation/top
This link relation identifies a link to the top (or root) node of a hierarchy. You can use links of this type to navigate from a tag to its owning tag structure, for example.
The following example shows a link of this type:
<entry> ... <link href="http://host-ip-address/webservice/escenic/classification/tag:folksonomy.escenic.com,2002" rel="http://www.vizrt.com/types/relation/top" title="Tags"/> ... </entry>