"The Nostalrius emulator had not been build from scratch by our development team. It stood on the shoulders of all the work that had been done before by the World of Warcraft emulation community, since 2003. Formally, Nostalrius was based on a 2009 MaNGOS version, which was forked from a late 2005 version of WoW Daemon, which used technical elements that were reverse engineered from the original client by previous teams. Nostalrius Burning Crusade project is based on a Q3/Q4 2015 version of this same emulator under a GPL v2 license."
https://www.docdroid.net/flUbn6G/nostalrius-post-mortem-pdf
