The bulk of Patsy is distributed under a simple 2-clause BSD license:

    Copyright (C) 2011-2012, Patsy Developers. All rights reserved.

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

       1. Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

       2. 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.

    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.

The module patsy.compat contains code derived from the Python
standard library, and is covered by the following license:

    PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
    --------------------------------------------

    1. This LICENSE AGREEMENT is between the Python Software Foundation
    ("PSF"), and the Individual or Organization ("Licensee") accessing and
    otherwise using this software ("Python") in source or binary form and
    its associated documentation.

    2. Subject to the terms and conditions of this License Agreement, PSF hereby
    grants Licensee a nonexclusive, royalty-free, world-wide license to reproduce,
    analyze, test, perform and/or display publicly, prepare derivative works,
    distribute, and otherwise use Python alone or in any derivative version,
    provided, however, that PSF's License Agreement and PSF's notice of copyright,
    i.e., "Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
    2011, 2012 Python Software Foundation; All Rights Reserved" are retained in Python
    alone or in any derivative version prepared by Licensee.

    3. In the event Licensee prepares a derivative work that is based on
    or incorporates Python or any part thereof, and wants to make
    the derivative work available to others as provided herein, then
    Licensee hereby agrees to include in any such work a brief summary of
    the changes made to Python.

    4. PSF is making Python available to Licensee on an "AS IS"
    basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
    IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
    DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
    FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
    INFRINGE ANY THIRD PARTY RIGHTS.

    5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
    FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
    A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
    OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.

    6. This License Agreement will automatically terminate upon a material
    breach of its terms and conditions.

    7. Nothing in this License Agreement shall be deemed to create any
    relationship of agency, partnership, or joint venture between PSF and
    Licensee.  This License Agreement does not grant permission to use PSF
    trademarks or trade name in a trademark sense to endorse or promote
    products or services of Licensee, or any third party.

    8. By copying, installing or otherwise using Python, Licensee
    agrees to be bound by the terms and conditions of this License
    Agreement.

As per item (3), we are required to provide a brief summary of
changes. For this, see comments in patsy/compat.py.