Hi Bernhard,
Computing and communicating the concluded or highest compatible licence is indeed out of scope for REUSE. There lie dragons that way. REUSE just communicates the status quo of a project's licensing---downstream consumers of a REUSE-compatible package can easily [sic] work out the highest compatible licence given the metadata provided by REUSE.
That's not to say you can't help downstream along. reuse-tool includes a 'Licensing' section at the bottom of the README that spells out the licensing situation in more detail than you can divine from `ls LICENSES/`.
But there is no standardised way to communicate that information, for a few reasons:
- Out of scope. - A concluded licence may be useless without information on how you arrived at that conclusion, which cannot be easily expressed in a machine-readable way, which is one of REUSE's core goals. - Downstream may _disagree_ about how you concluded your highest compatible licence. You may in turn disagree with downstream, but for all intents and purposes, you would be distributing false or contentious information. - It adds more duplicated work (and thus more vectors for getting this wrong), because people have to manually add their licensing situation to e.g. package.json anyway, and they probably also want to add it to their README.
However, there is obviously _some_ use-case for communicating this information. REUSE will not standardise this, but we already have provisions for this in v3.2 of the spec (unmerged).
You MAY include a `COPYING` or `LICENSE` file (with or without file extensions) in your project for compliance with other standards, conventions, or tools. These files MAY contain a copy of the license text, a summary of your licensing, or anything else. These files are ignored by the REUSE Tool.
See https://github.com/fsfe/reuse-docs/pull/133.
It may be prudent to add a note about this to the FAQ.
I hope that answers your questions, even if there's no real satisfactory 'this is how you do it' solution.
As a note, I'm going to be working on improving documentation on the website for the coming weeks. That area desperately needs a little love. These improvements won't be live for a while until v3.2 is released, but enfin. If you have suggestions for improvements of the documentation (something missing, something poorly phrased, something wrong), by all means feel free to open issues against the reuse-docs repository[1].
Yours with kindness, Carmen
[1]: This will be merged with the reuse-website repository soon-ish, hopefully, but I'll transfer the issues when that happens.