From: Tobias Peters <tpeters@...>
Date: 2002-07-03T22:33:24+09:00
Subject: RE: documentation licenses (was: eruby SAFE question)

On Tue, 2 Jul 2002, Austin Ziegler wrote:
> didn't change the licence on the BSD code. They used it in
> accordance with the licence. They licensed their complete work under
> their own licence, but the code permitted that.

Of course you're right. Only the copyright holder can change the license.

> All-in-all, I prefer
> licences like the MPL because they are very clear on the issue of
> derivatives.

I've just read the OPL, and although it is not written very clear, the OPL
is actually a copyleft license. It requires derived works to be put under
the OPL, although this requirement is somewhat hidden. In fact, from first
reading I got the impression that the license is BSD-ish, so I think, it
is easy to get that wrong without intention. Let me explain:

Paragraph I., labeled "requirements on both unmodified and modified
versions", includes the permission for redistribution and the requirement
of including a copyright notice with credits for the original authors.

Paragraph IV., labeled "requirements on modified versions" lists:

1.The modified version must be labeled as such. 
2.The person making the modifications must be identified and the
  modifications dated. 
3.Acknowledgement of the original author and publisher if applicable must
  be retained according to normal academic citation practices. 
4.The location of the original unmodified document must be identified. 
5.The original author's (or authors') name(s) may not be used to assert or
  imply endorsement of the resulting document without the original
  author's (or authors') permission.

=> No requirement on the license of derivative works in Paragraph IV.

This copyleft requirement is buried in Paragraph I., by demanding the
inclusion of the already mentioned copyright notice. Inside the demanded
form of the copyright notice, it says: 

"This material may be distributed only subject to the terms and conditions
set forth in the Open Publication License."

So it forces modified works to be licensed under the OPL only by demanding
the inclusion of a copyright notice. I would say, this is easy to
overlook. It should state so explicitly right in the text of the license.

So could you please shake hands again?

And the usual disclaimer when dealing with this subject: IANAL, this is
not legal advice.

Tobias