Surely now, but it started with OS 3.0 source ....
A rewrite means that it was written from scratch, no different to AROS or MorphOS.
http://www.morphos.de/team
As you do know, we poor bastards stand just with Frieden brothers and few other good men :-)
However, if you do take AmigaOS as continuation of AmigaOS, list looks good. And have some similar names.
Sadly its not the case today.
I don't take AmigaOS as a continuation of the Amiga OS. Firstly because it's a rewrite (Remember The Friedens vs Hyperion court case?), secondly if it were it would have the legal right to use the Amiga trademark, which it doesn't.
MorphOS started as a rewrite of the Amiga OS by the "superstar" coders of the Amiga scene who had spent the 90's keeping our beloved platform alive. OS4 started because a greedy wannabe lawyer and a greedy truck driver wanted to milk as much money as they could from what was remaining of our community.
Unfortunately for Billy and Benji most of the best coders had already started the MorphOS project and they were left with hardly anyone of note to write their Amiga OS clone "AmigaOS".
Well, there is always hope of small market for example making people working together.
The AROS and MorphOS teams have already worked together for years.
Soon I ll start thinking everyone has a Bosnian family :-)
Well I would have even more but the Chetniks brutally raped and murdered them.
But that's a story for the Coffee House forum methinks.