ksh93u+m is the ksh93 reboot aims to develop bugfixes to the last
stable release (93u+ 2012-08-01) of ksh93, formerly developed by
AT&T Software Technology (AST). This ksh 93u+m reboot now incorporates
many of these bugfixes, plus patches from OpenSUSE, Red Hat, and Solaris,
as well as many new fixes from the community.

Between 2017 and 2020 there was an ultimately unsuccessful attempt to
breathe new life into the KornShell by extensively refactoring the last
unstable AST beta version (93v-). While that ksh2020 effort is now
abandoned and still has many critical bugs, it also had a lot of bugs
fixed. More importantly, the AST issue tracker now contains a lot of
documentation on how to fix those bugs, which made it possible to
backport many of them to the last stable release instead.

The shells/ksh port tracks releases.