Faré wrote:

 OTOH, it's probably A Bad Thing if you depend on a system for something
 you are doing, and don't know what license it uses.

 Well, we haven't codified any format for :license. I suppose we could adopt
 the nomenclature used by Debian. Except what in Lisp circles goes by
 the name "MIT"
 (as notably used by ASDF itself) in Debian-speak is called "Expat".
 Also, we don't have a story for multi-licensed code either.
 For instance, I have code under LLGPL or bugroff, or BSD or bugroff.

I didn't mean that we needed a codified format.  I just meant that if
you are using a system, and the humans involved don't know if your usage
is legal (e.g., are you using pure GPL in a commercial application? are
you delivering source for libraries when you deliver your code? etc.),
that's a Bad Thing.

Given that :LICENSE is currently arbitrary string valued, we can just
make a string that indicates multiple possible licenses.

We could certainly add some standard values (keywords?) for common
licenses, and allow people to specify a list of such values (and an
optional string), but I'm not sure what we would gain by this.

I don't yet see a use case for machine-introspection on the :license,
but I'm open to suggestions.

 But that's why I created a special class of CONDITION for this case --
 so you can muffle it if you don't care.  It would be nice if there was
 some way to detect the distinction between internal systems (fix them!)
 and external systems (muffle).

 At ITA, we started with muffling the external systems, but quickly
 enough decided to fix them instead; code quality matters for libraries
 we depend on, too. But we did have a list of style-warnings to muffle
 and some of them were based on dependencies indeed.

For now a programmer could match the name of the system in my
MISSING-METADATA condition, and use that to make his or her decision
about muffling.

 I'll push my topic branch today.  It needs a test script, and I'd like
 to make it skip signaling on "slashy" subordinate systems, but I'd love
 comments in the meantime.

I pushed this as the QL-metadata-warning topic branch.

Best,
r