This license is a modified version of the MIT license, with an added clause that is specific to Docbook stylesheets. The clause makes the license GPL incompatible, though, in the use case of docbook stylesheets, this is unlikely to be a concern. However, it is noteworthy that this sort of clause, applied to software, rather than XML stylesheets, is likely to make a license non-free, so we do not recommend its use.
Copyright --------- Copyright (C) 1999-2007 Norman Walsh Copyright (C) 2003 Jiří Kosek Copyright (C) 2004-2007 Steve Ball Copyright (C) 2005-2008 The DocBook Project Copyright (C) 2011-2012 O'Reilly Media Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ``Software''), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. Except as contained in this notice, the names of individuals credited with contribution to this software shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the individuals in question. Any stylesheet derived from this Software that is publically distributed will be identified with a different name and the version strings in any derived Software will be changed so that no possibility of confusion between the derived package and this Software will exist. Warranty -------- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL NORMAN WALSH OR ANY OTHER CONTRIBUTOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.