Copyright in South Africa is conferred and regulated by the Copyright Act No. 98 of 1978 (the Act) which came into force on 1 January 1979
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You can copy the client, but cannot copy the server. Copying the server is a the violation.
'copying' a server means that you take a blizzard server and make an exact copy.
no private server is an exact copy, even if they want it to be they cant.
in fact most privates want to be different because some people dont particularly like the blizzard servers
Trinity and ManGOS servers, (the most common ones) are just alternatives to blizzard servers