[rodgerd]

Perhaps I'm misreading what appears to be the Mir license block:

GNU GPL v3, GNU LGPL v3, MIT / X / Expat Licence, Other/Open Source (Boost Software License - Version 1.0) Commercial subscription expires 2022-09-24

[mseebach]

What is there to misread? Boost Software License is there?

https://www.gnu.org/licenses/license-list.html :

Boost Software License (#boost) This is a lax, permissive non-copyleft free software license, compatible with the GNU GPL.