Package: base-files
Severity: wishlist
Version: 12.2
Expat and Boost-1.0 are both fairly common licenses in debian. I
believe they are both well-defined, stable, and reasonably
well-understood variants of the MIT family of licenses.
https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/ even
explicitly recommends that software with an "MIT" license that matches
the Expat terms should instead refer to Expat.
It would seem reasonable to include both of these licenses in
/usr/share/common-licenses/ to discourage adoption of other
less-well-known variants in the MIT family.
Boost has the advantage over "Expat" of being explicitly included in the
SPDX listing with a short name of "BSL-1.0":
https://spdx.org/licenses/
while Expat doesn't get its own identifier in that list, but instead has
the discouraged "MIT".