A migration to Solaris 10 occurred in 2013
although, with a
hat-tip to the Unix team working around failing ancient hardware,
Wood observed: "We have Solaris 10, running a Solaris 8 zone and
that zone is configured in Solaris 6 compatibility mode. (it
really is turtles all the way down!)"
Interestingly, according to the chart here
<https://en.wikipedia.org/wiki/Oracle_Solaris>, there was never a
“Solaris 6”. There is not even a “SunOS 6”.