directory:directoryname[:subDN]
i.e.
directory:Hosts directory:Hosts:ou=Lab
The directory URIs are composed of the keyword directory followed by a ":" character, followed by the name of a directory. Optionally, the directory name may be followed by another ":" and a relative DN of a sub tree within the specified directory. In this case the connection is made to this sub tree rather than to the whole directory.
1.4.5