Thank you! I knew it was from Andrew File System but did not manage to find those links by searching too narrowly.

DCE DFS (developed at Transarc) was originally supposed to be AFS 4.0 before it was contributed to DCE. After the contribution it became backward incompatible with AFS 3.x. The RPC layer, the authentication protocol, the protection service (user/group management) were all replaced to leverage technology contributions from other DCE participants.

IMO IBM/Transarc died for two reasons. First, there was significant brand confusion after the release of Windows Active Directory and Windows DFS since no trademarks were obtained for DCE service names. Second, the file system couldn't be deployed without the rest of the DCE infrastructure.

There was an unofficial effort within IBM to create the Advanced Distributed File System (ADFS) which would have decoupled DFS from the DCE Cell Directory Service and Security Service as well as replaced DCE/RPC. However, the project never saw the light of day.

https://en.wikipedia.org/wiki/DCE_Distributed_File_System

thanks : i hadn't known that larger context either, so very useful.