The icons are mostly derived work from other icons. As such they are
licensed accordingly to the original license:

Project                 License                   File
----------------------------------------------------------------------------
Enthought               BSD 3-Clause              LICENSE.txt

Unless stated in this file, icons are the work of Enthought, and are
released under a 3 clause BSD license.

Files and orginal authors:
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traitsui/images:
                          frame.png | Enthought