Use the Source/BSD's Not Unix
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Discuss how though BSD holds some design and even code from Unix it is not technically a Unix because it is not based on Unix code, just contains some now.
Discuss the freeing up of the old SysV code by Caldera, how that means a open source operating systems can now contain actual Unix code and could make an open source Unix.
Discuss Unix Certification, how any operating system can become a Unix if it meets special standards and pays for the testing.