[License-discuss] Changes made by derivative works

David Woolley forums at david-woolley.me.uk
Thu Jan 31 10:20:29 UTC 2013

Gervase Markham wrote:

> If you are writing a license, please don't include a line like this.
> Depending on how you interpret it, it's either ineffective (because the
> next person can simply remove your notices as part of their change) or a
> pain in the behind (as your file fills up with notices which are best
> maintained in your source code management system anyway). This makes
> such lines in existing licenses far more honoured in the breach than the
> observance.

The purpose of such clauses is not to track the provenance, but to 
maintain the purity of the  official version, so that forks cannot be 
passed off as approved versions.

> The days of tracking code provenance via in-file comments are gone. And
> they are not missed IMO.

One of the key objectives of open source is code re-use.  This means 
that a file must be usable outside the context of the original 
application, and therefore with a different, or no, source management 

If you are going to rely on a source management system, you must insist, 
in the licence, that any distribution of the code contains all the 
source management meta-data.  It is still standards practice to 
distribute source as a single version tar.gz or tar.bz2, i.e. without 
any of the meta data.

The meta data also often doesn't contain legal identity of the 
modifieres, and doesn't distinguish between de mimis changes, and ones 
where the modify owns copyright.

Requiring that the complete repository accompany the code would be a 
real dampener on open source.

There may be compromises, but the less information you include in a 
file, the more difficult it is to re-license it, once divorced from the 
original source management system.

Incidentally, source management systems are not new technology.  I would 
succest that they pre-date the formalisation of the open source concept.

David Woolley
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