While there are tools called "localedef" in Solaris and Linux, this
tool does not share heritage with any other implementation.  It was
written independently by Garrett D'Amore while employed at Nexenta
Systems, and thus carries the Nexenta Copyright.

It was initially released under the CDDL license, but on 4 July 2014,
Nexenta reissued the source under the BSD 2-clause license.  This
code is part of the Illumos project.

see:
https://github.com/Nexenta/illumos-nexenta/commit/cf17542a37fc83d0ae093777e30d480423858c29