[AppStream] Generalized SPDX licenses for metadata license

[Richard Hughes]

On Tue, 5 Jan 2021 at 02:33, John Scott <jscott at posteo.net> wrote:
> Is this the minimum set of licenses which implementations may
> accept, or the maximum?

It's an enumerated list, i.e. the only licence tag values allowed.

> It would be an artificial restriction for implementations not be allowed to
> accept others

A deliberate restriction I'm afraid.

> It is my hope that the AppStream specification retains its rationale for
> choosing permissive licenses, and enumerates its recommendations, but it be
> stated at least that using any other license identifier, SPDX or otherwise,
> results in unspecified or implementation-defined behavior.

Various legal teams need to agree on the combined set of licence
terms, it's not as easy as just adding one line in the spec and hoping
all the various generators and consumers of AppStream (be they
software components, or multi-billion dollar corporations) are
presumably okay with the changes. Changing anything to do with
licencing needs to be done super carefully.

Richard.