For all those 3 EC fans still left.
www.gamedeveloper.com
Due to the success of Mythic Entertainment’s “Dark Age of Camelot”, NetImmerse started to become associated with real-time MMORPGs, which – with the success of Ultima Online, Everquest, and Asheron’s Call – were very popular at that time.
A lot of energy was spent making everything backwards compatible. As a testament to the work that the team put into it, some NIF files from NetImmerse 1 could still be loaded into Gamebryo Lightspeed, over 10 years later.
It didn’t always work, though. Tim said, “We did break it once somewhere on NetImmerse 2 and that made [Mythic Entertainment] very unhappy, because they had a whole bunch of assets that they had already exported, and they didn’t have the master files for them anymore. They went back and wrote a NIF converter for that specifically. After that, we would deprecate features now and again, but we would always make sure that there was a NIF converter”

Classic Tools Retrospective: The birth, death, and re-birth of Gamebry
David Lightbown talks to Dan Amerson, Mike Daly, John Austin, and Tim Preston about the Gamebryo engine and tools. This article traces its history from NetImmer