The cell namespace's hierarchy model is different from the GDS model, and the CDS rules do not enforce any particular model; CDS allows entries containing any kind of data to be created anywhere in the namespace. Thus, CDS offers a free-form namespace in which entries and directories can be organized as desired, and in which any entry or directory can contain any attributes. The CDS administrator can create additional directories, and applications can add name entries as needed; applications cannot create CDS directory entries. Because of this, and because the cell namespace is so important to the operation of the cell, application developers and system administrators have more responsibility in planning and regulating their use of it.
The cell namespace has a structure similar to that of a UNIX file system. The CDS namespace is a tree of entries that grows from the root downward. The name entries are organized under directory entries, which can themselves be subentries of other directories. The cell root (represented by the prefix /.:) can be thought of as the location you get when you dereference the cell's global name. New directories and new entries within the directories can be added anywhere in the tree, subject to the restrictions mentioned previously.