compiler/docs/elm.json/package.md at 912b31ea6460379665acb630635d451350fd28e9 · elm/compiler · GitHub
https://github.com/elm/compiler/blob/912b31ea6460379665acb630635d451350fd28e9/docs/elm.json/package.md#license
> ## `"license"`
> An OSI approved SPDX code like `"BSD-3-Clause"` or `"MIT"`.
処理系レベルでこれを強制してくるというのも中々思想が強いな