Verbatim license terms from
RTL/Kernel/Include/IFXQuaternion.h in U3D 1.5.2:

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This software is provided 'as-is', without any express or
implied warranty.  In no event will Nick Bobic be held
liable for any damages arising from the use of this software.

Permission is granted to anyone to use this software for any
purpose, including commercial applications, and to alter it
and redistribute it freely, subject to the following
restrictions:

1. The origin of the software must not be misrepresented;
you must not claim that you wrote the original software.
If you use this software in a product, an acknowledgment
in the product documentation would be appreciated but is
not required.
2. Altered source versions must be plainly marked as such,
and must not be misrepresented as being the original
software.
3. This notice may not be removed or altered from any source
distribution.
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