In <https://fossbazaar.org/pipermail/spdx/2010-September/000116.html> dmg brought up and interesting question regarding how similar two license texts need to be before they can be considered the same license.  This got me thinking about the proposed license templates.

I am increasing uncomfortable with the idea of spdx specify a mechanism intended to support recognition of licenses.  That very idea seems fraught with peril, both technically and legally. 

What constitutes similar enough to treat as a single license is a policy decision.  Risk averse organizations with a high profile might choose a relatively high bar for sameness, while less risk averse organizations will probably prefer a lower bar.  I think setting these policies should be left to the producers and consumers of spdx files.  These parties are the only ones with enough information to do it effectively.

There are a few situations where a light weight template syntax in the license text field itself would be useful.  Such a syntax would allow a way to demarcate really obvious and uncontentious replaceable parts of the license.  Square brackets around a description of the replaceable element would probably sufficient.  For example, the 3 clause bsd license text would look like this

Copyright (c) [YEAR], [OWNER]
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• Neither the name of the [ORGANIZATION] nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

This would allow spdx to provide canonical forms of licenses without trying to specify policy issues.

Peter Williams
<http://openlogic.com>