Found the dll in https://community.emc.com/docs/DOC-3501 but it is still early access technology and requires changes on the server side also. Supposable a version will be released with 6.7. Very annoying that the standard sdk includes examples that use this dll.
using emc-dfs-sdk-6.5_sp3.zip, trying to build a .net Desktop app. Can not find the reference "Emc.Documentum.FS.Runtime.Ucf" which is used in example
UCFContentTransfer and also mentioned in doc UCF client for .NET + DFS integration
https://community.emc.com/docs/DOC-3501
It appears that this has been dropped from .Net.
It still exist in java world
<emc-dfs-sdk-6.5 install root>/docs/java/api/runtime/com/emc/documentum/fs/rt/ucf/UcfConnection.html