Can reuse accept SPDX-License-Indentifier: NONE?

[kikofernandez]

Hi,

I was wondering if it makes sense to add SPDX-License-Identifier: NONE and SPDX-FileCopyrightText: NONE (and their NOASSERTION counterparts) to ReUse.

I understand that these are not licenses, but I think some projects have been running for more than 30 years and it is just unfeasible to know what the copyright and license at the time was. The information to ask those authors have been lost.

As an example, the Erlang programming language has some example sections contributed via mail patches more than 30 years ago, and it is impossible to ask that author now, because the information has been lost when going from the original CVS to the current git repo. We can only assume that the contributor accepted the project license, since no other license was mentioned.

Just checking if this is something useful, or if ReUse prefers to keep the linter to only consider valid projects that have a proper license.

Thanks for all the good work on this project.