On 12/13/23 01:17, John Cowan wrote:
> Let me quote the definition of AND from SPDX 2.2.2:
>
> If required to simultaneously comply with two or more licenses, use the
> conjunctive binary "AND" operator to construct a new license expression,
> where both the left and right operands are a valid license expression
> values.
>
> For example, when one is required to comply with both the LGPL-2.1-only
> or MIT licenses, a valid expression would be:
>
> |LGPL-2.1-only AND MIT|
>
>
> However, in the general case the terms under which a derivative work is
> licensed do not include the license terms of the original work.  For
> example, if Alice writes a book and licenses Bob to make a movie from
> it, the licensing terms of the movie are chosen by Bob, and have nothing
> to do with the terms of Alice's license with Bob (unless Alice so
> requires).  AND, therefore, is inapplicable.  If Alice uses a strong
> copyleft license like the GNU GPL, then she is imposing such a
> requirement, but if she chooses a weak copyleft or "copycenter" license,
> there is no such requirement.

Either I still don't understand the kinds of cases you have in mind or I
understand the requirements in those cases differently. (I am still not
a lawyer.)

Taking one of your concrete examples:

On 12/12/23 17:49, John Cowan wrote:
 > 1) the text of SRFI 170, which is an MIT-licensed work derived from a
 > BSD-licensed work, and therefore must include a copy of the BSD license,
 > a copy of the MIT license, and SPDX metadata for the MIT license only;

The BSD-3-Clause license permits "redistribution and use …, with or
without modification," under conditions including "retain[ing]" or
"reproduc[ing] the above copyright notice, this list of conditions and
the following disclaimer."

A derived work is a modification, so downstream recipients of SRFI 170
must fulfill the BSD-3-Clause conditions for "redistribution and use" of
the original work. Simultaneously, the MIT license applies to the new
material added for SRFI 170. (The MIT license likewise requires that its
notices "shall be included in all copies or substantial portions of the
Software," even if those copies are part of a derived work adding new
material under yet another license.)

So it seems to me that the appropriate license expression for SRFI 170
is (BSD-3-Clause AND MIT).

Philip