PATH
The name graph is based on an anonymous, unnamed root entry under which all other entries live. This root does not appear in pathnames, and it can be referenced only indirectly, using null for its parent entryID value.
Given a parent entryID value and the pathname :aaaa:bbbb, aaaa is a child of the specified parent name entry. If the specified parent name entry is null, the root entry is assumed to be the parent and the path is equivalent to an absolute path.
Names for the entries just below the root (children of the root) are generic names representing categories of things such as devices, processes, volumes, and so on. As you move down the tree the things become more specific, depending on their organization within each category.