Re-using copyrighted code

[Mark Janssen]

> At least partially, my confusion seems to be caused by the dichotomy of
> the concepts of copyright and license. How do these relate to each other?

A license emerges out of the commercial domain is purely about
commercial protections.   A copyright comes from the "academic" domain
is pure about protecting your "intellectual property", or non-physical
creations (most from encroachment of the commercial domain, by the
way).   They are on opposite ends of the spectrum, but because of our
bi-polar system the terms get used as synonyms .

In a way they are not related and it all depends on what court would
listen to the case.  In a German court, you would almost certainly be
tried under the commercial framework,  In the US, in theory (and this
is where it must be pushed to enforce the people), it *should* be the
opposite if the court is doing its job of upholding the Constitution.

You use a license when you want to authorize use of something you own
in a commercial setting.  You use copyright when you're protecting
authorship of something and have not given it away (something you
never really want to do anyway).

> I understand that I have to pick a license for my package.

You actually do not.  Attaching a legal document is purely a secondary
protection from those who would take away right already granted by US
copyright.

> And may be
> I'm not free to pick any open source license due the license used by
> Secret Labs AB. But how does that relate to the copyright statements?

The thing, like I noted, is that they've already released the code
into the public eye.   Now you must only do your due diligence to
honor the *spirit* of their intent.  And that spirit, regardless of
whether they made it explicit, is almost certainly for non-commercial
(non-profit) use.

> Should I put my own copyright line in every source file in the package?

I would put it as a separate file in the package as well as a comment
line in each file referring to your file.

> How about the file that re-uses portions of sre_parse.py? Can there or
> should there be two copyright lines in that file, one from Secret Labs,
> one my own?

Show (c) YourName, Secret Labs and carry-forward any additional usage
terms from them.

-- 
MarkJ
Tacoma, Washington