some info I found was back in 2011 when BetaArchive member WinPc made the following quote
This could confirm the possibility of an early Longhorn/Idaho build list! but again could be fake. It would also be useful to know what NT version it would be. so If you have any info, tell me about it!I'm currently working on a revitalization of the Microsoft OS checklist for The Beta Group and AbandoNet. One of the things I'm doing is transcribing my November 2008 version of the old list that I released on the OSBetaGroup (now known as AbandoNet) into an easier-to-manage format; anyway, I recently got to the "Idaho"/"Longhorn" builds, and also finished all the alphas of "Longhorn", and as such, if anyone would like a copy of the checklist, even though it's for The Beta Group and AbandoNet, I'll send it to anyone who wants it, as long as the other people involved in this project approve of it (it is possible that I might have to remove some information that certain people might not want circulating outside of their groups, but I certainly won't have to remove any Longhorn builds).
However, if anyone would like it posted publically, I could instead post the "Idaho"/"Longhorn" list here without sending anyone the entire list.